pilot study: camden catchment



pilot study: camden catchment
Coastal Region Environmental
Assessment and Management
Technical Report 4:
The Camden Haven estuarine fishing and oyster
cultivation industries
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This report presents a review of the N.S.W. estuarine
fishery, data on the Camden Haven estuarine fishery and
data on the Camden Haven oyster CUltivation industry.
The statistical information presently collected does not
allow for any detailed analysis of the ecological nature
of the estuarine fisheries of N.S.W. Conclusions on the
condition of the Camden Haven estuary are restricted to
general comments because of this lack of relevant data.
Suggestions for revision and alteration to the method
and content of data collected on both estuarine fisheries
and oyster CUltivation are presented. Suggestions for
further research and the establishment of a series of ongoing monitoring programmes are included within the
,- "
A report to the Coastal Council of N.S.W.
Colin Creighton, University of New England,
Armidale, 1984
7 Angourie Street, Angourie, N.S.W. 2464
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Content and Principal Aim of the Camden Haven
Regional Study
Delineation of the Study Areas
Camden Haven Study - Report Structure
Biological Monitoring and Indices
Estuarine Fisheries of N.S.W. - their nature
Condition of a Fishery
Estuarine Waters and Fluctuations in
Environmental Parameters
History of the N.S.W. Estuarine Fishery
Methods of Capture
Principal Species of the N.S.W. Estuarine Fishery
The Relationships Between Estuaries and
Inshore/Offshore Fisheries of N.S.W.
Biological Monitoring at the Community Level - the
Selection of Suitable Indices for an Analysis of
Estuary Condition
Fisheries - methods of assessment
Estuary Condition and Estuarine Fishes - the
selection of indices
History of the Camden Haven Fishery
Catch and Life History Features of Selected Species
River garfish (HemiphamphuB ardeZio)
Dusky flathead (PZatyaephaZus
Flattail mullet (Liza argentea)
Luderick (GipeZZa tPiauspidata)
Sand whiting (SiZZago BiZiata)
Sea mullet (MUgiZ aephaZU8)
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Sand mullet (MYxus eZongatu8)
Other Species Significant Within the
Estuarine Catch
Community Assessment
Perceived issues - Camden Haven Estuary Fishery
Estuary Condition and N.S.W. Catch Statistics
N.S.W. statistics - Suggestions for Alterations
to Method and Content of Data Collected
The Sydney Rock Oyster (Saccostrea commerciaZi8)
and Estuary Condition
Factors Affecting Total Production
Oysters and Water Quality
History of Harvesting and Cultivation of Oysters
Within the Camden Haven Estuary
Hypothetical and generalized curve of historical
development of a fishery (after Kesteven, 1971)
Total catch of fish in estuarine waters of N.S.W.,
Annual fish catch, Camden Haven fishery, 1890 to 1981
Effort, Camden Haven estuary fishery, 1900 to 1981
River garfish, total catch Camden Haven and N.S.W.,
1940 to 1981
River garfish, seasonality of Camden Haven catch,
1980 to 1981
Dusky flathead, total catch Camden Haven and N.S.W.,
1940 to 1981
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FtGURE 13:
Dusky flathead, seasonality of Camden Haven catch,
1980 to 1981
F1attail mullet, total catch Camden Haven and
N.S.W., 1953 to 1981
F1attail mullet, seasonality of Camden Haven
catch, 1980 to 1981
Sea mullet, total catch Camden Haven and N.S.W.,
1940 to 1981
Sea mullet, seasonality of Camden Haven catch,
1980 to 1981
Sand mullet, total catch Camden Haven and N.S.W.,
1953 to 1981
Sand whiting, total catch Camden Haven and N.S.W.,
1953 to 1981
Sand whiting, seasonality of Camden Haven catch,
1980 to 1981
Luderick, total catch Camden Haven and N.S.W.,
1940 to 1981
Luderick, seasonality of Camden Haven catch,
1980 to 1981
Seasonality of prawn catch, Camden Haven
estuary, 1981 to 1982
Variation in species composition of Camden Haven
estuary catch, 1940 to 1981
Catch per unit effort (approximate), Camden Haven
estuarine fishery, 1948 to 1982
Bream, seasonality of Camden Haven catch,
1980 to 1981
Trumpeter whiting, total catch N.S.W. and
proportion caught within inshore waters
Oyster production, Camden Haven estuary,
1883 to 1980
Area of capture, fish species
Luderick movements, Hastings Entrance
Bacterial contamination - ·availab1e data,
sources and application
Context and Principal Aim of the Camden Haven
Reg lona I Study
The Coastal Council of N.S.W. was established under the N.S.W.
Coastal Protection Act (1979). The principal functions of the Coastal
Council as defined by the Coastal Protection Act are as follows:•.• to give advice and make reports and recommendations to the
Minister [Planning and Environment] for the purpose of
encouraging, promoting or securing -
the protection and maintenance and, where practicable, the
enhancement and restoration of the environment of the coastal region and its natural and man-made resources; and
the orderly and balanced utilisation and conservation of
the coastal region and its resources, having regard to the
financial resources of the state and the social and economic
needs of the people of the State.
It was the contention of this author, that for the Coastal Council
to fulfil these functions, a method of coastal region environmental assessment was required. In March 1980, through the University of New England,
the present project was initiated. The project had as its principal aim,
the definition, application and appraisal of a method of coastal region
environmental assessment. The method of assessment was structured so as to
include those aspects that would facilitate land use allocation and land
use management within the ~.S.W. coastal region. To provide practical
application and evaluation of the method, the Camden Haven region (midnorth coast of N.S.\~.) was selected as the pilot study area.
During 1980 the project developed through discussion with [email protected]
research workers and t~ collection of available data on the Camden Haven
region. A method of~essment was formulated. Aspects requiring field
investigation were defined and methods of data collection selected. Field
work proceeded during 1980. In January 1981, a Research Grant was obtained
from the Coastal Council of N.S.W. This grant enabled the author to purchase necessary equipment and instruments and to carry out further field work .
The provision of this grant is gratefully acknowledged.
Definition of the Study Areas
No specific definition of the coastal region is contained within
the N.S.W. Coastal Prot~otion Aot (1979). This author, in recognition of
the biophysical linkages between land and water areas of a catchment,
defined the coastal catchments of N.S.W. as comprising the 'coastal region'.
The patterns of landform that comprise this 'coastal region' may be agglomerated within specific catchment types with defined landform, land use and
process characteristics. For example, with respect to the estuaries of the
N.S.W. coast, Roy (1982) suggested that there were three distinctive types.
There are as follows:-
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Drowned river valley estuaries with full tidal exchange.
Barrier estuaries with attenuated tides.
Saline coastal lakes with ephemeral entrances and no
The Camden Haven region was sub-divided with respect to catchment type:- the Lake Cathie-Lake Innes catchment (coastal lake system,
ephemeral ocean entrance) and, the Camden Haven catchment (barrier
estuary). Methods of assessment, while similar in principle, varied in
specific detail for each of these study areas. Recommended management
strategies resulting from the research varied accordingly.
The Lake Cathie-Lake Innes catchment was the subject of a
separate report (Creighton,1983). The results of research of the Camden
Haven catahment are presented within a series of technical reports.
Camden Haven Study - Report Structure
Technical Report 1 (Creighton and Morgan, 1982) detailed the
catchment approach to land use planning and management. Using a geneticbased method of land appraisal, land areas of the catchment were mapped
within land systems. Selective mapping of land units allowed for the
delineation of coastal lands and uplands. Mapping of the land resource
in this fashion facilitated the definition of specific land use allocation
and land use management guidelines.
Technical Report 2 (Creighton, 1984) reviewed available data on
the physical and biological attributes of the Camden Haven estuary. Data
detailing the variation of salinity, temperature and light penetration
within the estuary was collected and collated to the available data.
Technical Report 3 (Creighton, 1982) presented data on water
quality. water quality data for the Camden Haven River above the tidal
limit was reviewed. Field investigations included the identification of
point resources of bacterial contamination (via contamination levels within oysters) and the collection of data on dissolved oxygen concentrations
within the estuary.
Technical Report 4, provides data on the oyster
cultivation and commercial fisheries of the Camden Haven. A review of
the N.S.W. estuarine fishery and a method of assessment of estuary condition based on available data ar~presented . in Part I o~ this re~t.
Part II of the report details the Camden Haven estuary fishery. The
oyster cultivation industry of the Camden Haven is detailed in Part IIIof
this report.
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Biological Monitoring and Indices
Biological monitoring is a method whereby changes in an
environment are assessed through the responses of animals and plants.
Davie (1975) suggested that biological monitoring has many advantages over
traditional monitoring techniques, but that the most important advantage
that it may provide the most sensitive and meaningful method of measuring impact on the environment.
This research project has as its principle aim, the definition,
application and appraisal of a method of coastal region environmental
assessment. Man's actions within the coastal region manifest themselves
through varied impacts upon the estuarine environment (e.g., Sorenson,
1974; Hodgkin, 1974; Lenanton, 1974). Biological monitoring via the
selection of specific indices may allow for the on-going assessment of
environmental conditions within the estuaries and lagoons of the N.S.W.
coastal region. The aim of this portion of the research project is to formulate and appraise methods whereby available data may be used for such a
The ACMRR/IABO Working Party (1976) suggested that an index may
be defined as a variable which measures the response of a system (a population, community or ecosystem) to some stress or stimulus. With respect
to the selection of suitable indices, this group stated the following:Busy decision-makers and the public-at-large prefer to deal with
formulations that are simple numerically or graphically. Thus
the search for measurable characteristics of stimuli and responses
is usually focused on simple indices and simple functional relationships. Though rather complex mechanisms may be known to underlie ecological interactions, a simple rationalization should be
sought at the outset which may well satisfy the decision-maker, if
not the scientist trying to gain deeper understanding of the
operation of the system in question. The fate of such simple formulations will be deterndned by tiheirpractical performance.
Within this investigation of the Camden Haven estuary, indices for
estuarine condition~ formulated and described via the use of available
data for commercial fisheries and oyster cultivation. These data, albeit in
varied forms and degree of accuracy, are routinely collected. Later discussion will detail past and present data collection methods, together with
comments on the extent and relevance of the data presently collected.
Recommendations for reappraisal and alteration of the methods and nature of
data collected are detailed. These recommendations are based upon the
results of this research project - particularly the practical performance of
the simple formulations chosen to exploit available data as indices of
estuary condition.
To provide a context for this investigation the following discussion provides information on the nature of the estuarine fishery resources.
A review of methods for the assessment of fisheries and the description of
a method of appraisal suitable for this investigation complete this background discussion.
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2. 2
Estuarine Fisheries of N.S.W. - Their Nature
2.2 .1
Cond ition of a Fishery
Kesteven and Burdon (1971) detail the characteristics of fishery
resources. They suggested that while fisheries have similarities with
other primary industries engaged in the exploitation of natural resources,
fisheries have particular characteristics which affect both their nature
and, their management. These characteristics are as follows:the natural resources are living and renewable;
the resources exploited are wild and to these man makes no
contribution (c.f. aquaculture which has characteristics
similar to agriculture);
because the resources are wild, man cannot control what is
to be available for harvesting at any time; (under these
circumstances Kesteven and Burdon suggested that management
should incorporate studies of the resource and habitat, thereby allowing for the exploitation of the resource at the most
opportune time);
the fishery resources are generally common property - Kesteven
and Burdon suggested that because of this, the amount of
effort applied is not subject to the restraints that govern
exploitation of a solely-owned resource. Consequently, governments have a more direct and continuing responsibility than
would normally be acceptable for other industries;
the circumstances of fishing operations encourage both a high
degree of individualism and, an opportunist philosophy amongst
those involved in the industry. To quote Kesteven and Burdon:Fishing is an irregular, intermittent occupation which is
largely dependent on the weather. But even when this is favourable, the taking of a catch depends on whether the fish are
located, prove to be vulnerable to capture, and the gear is
successfully operated. In consequence, catches, fishermen's
income, and market supplies are subject to marked uncertainty;
fish as a product presents specific problems in handling and
marketing. These problems include, the perishable nature of
fish, transport, refrigeration, storing and processing. These
problems are aggravated by the uncertainty of supply.
The characteristics of the Australian fishery resource and its
products are detailed by the Report of the Senate Standing Committee on
Trade and Commerce (1982). The Report discussed the nature and quantity of
the resource base noting that by world standards the resource base is not
large. With regard to particular fisheries, all areas of effort were
classified with respect to the level of exploitation presently apparent.
The Senate Standing Committee suggested that the inshore/estuarine fisheries
were amongst that group of fisheries that are already fully developed.
Kesteven (1971) provided a more detailed perspective on which to
base interpretations of the stage of development of a fishery. Kesteven's
generalized curve of the historical development of a fishery is reproduced
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(El SEcOND ST•• •
,a) ""n
ST . . ..
lurED PHAir
1 .... ,
.. -- ...
lunD PHAS€
OF ArSOt.a
Hypothetical and generalized curve of historical development
of a fishery (after Kesteven, 1971).
in Figure 1. Kesteven developed five primary categories of industry
status in an historical sense. These are as follows:-
Nascent fishery: resource discovered but not fully quantified,
experimental catches only; the east coast Orange Roughy (HopZostethus
atZantiaus) or the North west Shelf Scampi (Metanephrops andamaniauB)
fisheries could be classified as being presently in this category.
Developing fishery: These fisheries are characterized by
increased catches and, significant increase in both effort and equipment;
Kesteven described the latter part of this phase as follows:- At some
stage the industry is expanded fully to the limits of the resource and no
further increase in catch is possible, and we may note that the ultimate
size of each fishery is determined by the size of the resource. The
fishing mortality brought about by fishing effort itself brings about
changes in the stock and these are reflected in the catch. Generally
fishing operations reduce the overall size of the population, the range
of size and the relative strength of different age classes in the population, and hence the average size and average age of the individuals.
The East Coast Royal Red Prawn (HaZiporoides sibogae) and gemfish fisheries
are at present within this general category of "developing fishery".
Stabilized fishery: The general appearance of a stabilized fishery
is of minimal change. So far as the fish resource is concerned, the
essential characteristics are that natural and fishing mortality are more
or less in balance with growth and reproduction. Fishing equipment and
techniques used coverge upon a standardized pattern. A present example of
such a fishery is the N.S.W. king prawn (Penaeus pZebejus) fishery.
Kesteven suggested that, at time of writing (1970), the estuarine fishery,
particularly the sea mullet (MUgiZ aephaZus) fishery was in such a category.
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Changes observed by this author over the past five years suggest that the
mullet and, the estuarine fishery in general, may now be in Kesteven's
fourth category, the declining fishery.
Dec I ining fishery: A principal feature of this condition is a
steady reduction of the . stock, the onset of which may be concealed by an
intensification of fishing effort so as to ensure the maintenance of the
catch. The equipment in such a fishery becomes neglected and is kept in
operation beyond its normal life.
The Clarence estuary mullet fishery is presently in this condition. Quotas that in the 1950-60s could be fulfilled in several days/
week effort are now largely unfulfilled.
Equipment used is often substandard. Those remaining in the fishery have increased effort with a
significant propotion of the fishermen previously involved now employed in
other sectors of the industry, such as the prawn fishery.
Further detail of the east coast mullet fishery and the estuarine
fishery in general is presented in later discussion. At this point, however,
it should be stated that the analysis of condition of a fishery involves
the incorporation of a series of interrelating factors (e.g., Thomson, 1953).
These factors as they relate to the Camden Haven estuarine fishery, dominate later discussion. For the moment it is sufficient to suggest that the
estuarine fishery of N.S.W. may be classified as either in an extended phase
of stabilization or, in some cases, in a state of decline.
Extinguished fishery: A fishery in this condition has ceased
operations. The resource may have been reduced by fishing effort to such
an extent that operations are no longer viable (e.g., the east coast
whaling industry) or, there has been a disappearance of demand for the
product (e.g., the Australian pearlshell fishery) or, environmental conditions are such that the resource is no longer available in viable
quantities (e.g., oyster, SaaaoBt~ea aomme~aialiB, dredge beds of the
N.S.W. estuaries).
The preceding review of Kesteven's (1971) classification of the
stages of development of a fishery provides a context within which to
detail the present N.S.W. estuarine fishery. Aspects requiring detail
include the nature of estuarine waters, the history of the fishery, the
methods of capture, species exploited and the relationships between species
and the surrounding environment, measures that have been effected to regulate the harvesting of the resource and, the relationships between estuarine
fisheries and inshore/offshore fisheries (fisheries are as defined by
Pollard, 1976).
Estuarine . waters and fluctuations in
environmental parameters
Within this research project a distinction has been made between
barrier estuaries and coastal lagoons. This distinction was based upon
the recognition that the particular aggregation of land and water resources
that comprises a lagoonal catchment differs markedly to those of a barrier
estuary. Similarly, differences exist between barrier estuaries and the
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more marine-dominated emb·ayments of drowned river valleys (e.g., Thomson,
1959b,e; SPeC, 1981).
The results of research within the Cathie-Innes lagoonal system
were presented in Creighton (1983). Regarding the fishery resource of
this system, it was found that both conditions and catch rates varied
markedly with entrance condition. It is the contention of this author
that the management of these differing resource types should vary according to their particular characteristics. For example, Creighton (1983)
recommended that the present largely ad hoc artificial opening of lagoonal
ocean entrances requires detailed re-assessment. Present management
philosophies are generally underlined by the assumption that wherever
possible, barrier estuary conditions should be achieved. Such a philosophy takes no account of the conditions, biota and productivity of the
lagoonal systems during periods of entrance closure and high water levels
of reduced salinity. Aspects such as the population dynamics of the
entrapped fish resource, the utilization of the lagoonal systems by
nesting waterfowl and the prevailing coastal processes should be fully
considered bofore approval for artificial opening of these systems is
The contribution of each of the various component estuary types
to the total estuarine catch within N.S.W. waters is at present undefined.
Recent statistics do not allow for the analysis of the estuarine fish
resource on this basis. For the remainder of this report discussion is
centred upon the characteristics of the fish resource of N.S.W. barrier
estuaries. Barrier estuaries are as previously defined (Roy, 1982).
Natural 'baseline' conditions within barrier estuariee vary.
Day (1951) emphasized that the distribution of flora and fauna within
an estuary cannot be based on a single factor of the environment. He
suggested that a complex of periodically changing parameters limits the
colonization to a restricted number of organisms with a wide range of
ecological adaptions. Hodgkin (1978) discussing the estuarine environment and variation within particular representative parameters, stated
the following:- An estuarine environment is one of constant change, both
spatial and temporal, one where biologically significant environmental
parameters may vary over an extreme range, both in space and time. Not
only is there change on this scale in salinity, but in water flow, temperature, turbidity and light penetration, nutrient supply, predation
pressure and even in this sheltered situation, in degree of wave action.
They add up to a complex of environmental change, the several strands of
which are difficult to disentangle; together they determine the nature
of the estuarine ecosystem.
Spatial and temporal variation of a series of environmental
parameters for the Camden Haven estuary were presented in Technical
Report 2 (Creighton, 1984). Data on the fluctuation of salinity, temperature and light penetration in response to varying climatic conditions
was collected. Further data, collected from various sources, was reviewed
and collated to the~ata on salinity, temperature and light penetration.
These data included the characteristics of freshwater discharge to the
estuary, the tidal characteristics of components of the estuary system
and, the distribution of benthic flora.
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The environmental changes that occur in barrier estuaries
may evoke particular responses of feeding activity, growth rate,
fecundity and so forth within fish species (e.g., SPeC, 1981; Hodgkin,
1978; Hill, 1982; Glaister, 1978a,b; Thomson, 1959c,e). The consequential changes in the overall competitive efficiency of one species
relative to the others with which there are interactive relationships
may generate biological chain reactions that could significantly alter
species composition and spatial patterning of communities (ACMRR/IABO
Working Party, 1976).
It follows that no biological measure utilized as an index
need necessarily remain constant. Rather, there are spectra of values
which encompass the normal range of responses. This complicates the
selection and application of specific indices of estuarine condition.
To some degree, this may be accounted for by the study of the system
over a long period. Unfortunately, as is detailed in the following
discussion, data on the early period of development of the N.S.W. estuarine fishery is largely non-existent. Data presently collected is more
suitable for such an analysis, however inadequacies in the content of
data collected are still apparent. This is discussed in detail with
reference to the Camden Haven estuary in Part II of this report.
History of N.S.W. estuarine fishery
Tennison-Woods (1882) detailed the estuarine fisheries, methods
of capture and regulations as they relate to the development of these
fisheries in the late 19th century. Even during this 'nascent-development'
phase of the estuarine fishing industry, it was recognized that the
estuary areas were important, at least as nursery areas if not as spawning
areas. He commented as follows:- The bays and creeks of every harbour
and the still waters of every lake and river swarm, under natural conditions, with the young of these fish [sea mullet, snapper, the breams,
the garfish, blackfish and whiting] in all stages of development •.. We must
protect the spawning fish and their young fry in the inlets, if we desire
to prevent the absolute extinction of the best of our food fishes.
Burdon (1971) discussed the development of the Australian
fishing industry in total, presenting detail of catch of scale fish over
the period 1905 to 1970. He discussed the impact on total fish catch of
improved transportation and marketing, changes in methods of capture, the
establishment of new fisheries such as the prawn and tuna fisheries and
the impact of socio-economic conditions such as the Depression and World
War II on effort.
Thomson (1953) provided extensive detail on the development of
the estuarine fisheries of N.S.W. and Qld. The reader is referred to this
paper for a discussion of all aspects of the fishery over the period 1910
to 1950.
Figure 2 presents the total fish catch in estuarine waters of
N.S.W. over the years 1910 to 1980. The estuarine catch in N.S.W.
increased from the beginnings of the fishery to a peak in 1915 after which
the fishery maintained a fairly constant catch until 1924 when a marked
drop in catch occurred. The fishery stabilized at this new level until
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1910 to 1980.
Data presented extracted from N.S.W. State Fisheries Annual
Reports and correlated to Thomson (1953);
Effort data not available; Thomson (1953) presents an
indication of CPUE for the period 1910 to 1950. The
development of the prawn fishery and the lack of representative data prohibits continuing this analysis to the
1930 when a further reduction in total catch was recorded. The fishery
then showed signs of recovery with catches exceeding the 1915 catch in
the years 1940, 1942, 1943, 1944 and 1945. Over the period 1945 to 1951
there was a continued reduction in total catch, with catch in 1951 and
for all the following years exoept 1953, being less than the previously
recorded minimum catches of 1930 and 1931. Apart from some slight increases in catch in the mid-1950s and 1970s, total catch over the period
1953 to 1979 has remained relatively constant with an average annual
catch over the period 1960 to 1978 of 3.74 x 10 6 kg. Slight increases
in the mid-1950s and 1970s may be associated with the recovery of
estuarine systems following the significant flood events that were experienced immediately prior to these periods.
Thomson (1953) presented an indication of effort by the use of
catch/man over the period 1910 to 1950. No data are available which
accurately portrays effort over the period 1950 to 1980. Fishermen over
this period have become increasingly involved in various sectors of the
industry, moving from say the prawn to scale fish fisheries as a function
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of seasonal abundance. As Thomson noted, even if this information was
available, the relationships between availability and true abundance of
population need not necessarily remain constant.
Kesteven (1942) discussed the estuarine fishery prior to 1938.
He suggested that depletion existed due to overfishing. Thomson (1953)
discussed Kesteven ' s findings and suggested that Kesteven's interpretation, while justifiable in the light of current theories did not
adequately portray the characteristics of the estuarine fishing industry.
Thomson suggested that a number of factors omitted by Kesteven should be
considered. These factors included the variation in effort as a function
of the economic climate, the temporary and in some cases permanent transference of effort to other sections of the industry, fluctuations in
market demand, natural fluctuations in fish populations and alteration of
the carrying capacity of estuaries as a function of conflicting and
impacting land uses within the coastal catchments.
Each of these factors are relevant to a discussion of the total
catch over the period 1950 to 1980. A further factor, catch by amateur
fishermen has become of increasing significance over this period (e.g.,
Pollard, 1976: Cheng, 1981). As to the degree with which each of these
factors has affected the total catch, this is open to discussion.
Certainly, there has been a continuation of natural fluctuations in fish
populations. The post-flood periods of the mid-1950s and 1970s, were
previously mentioned. Similarly, there has been fluctuations in market
demand. For example, gluts of sea mullet on the market are to some extent
still present.
The one factor that perhaps above all others has increased in
importance over the post-World War II period is the alteration of the
carrying capacity of the estuaries. This was alluded to in the N.S.W.
State Fisheries Annual Report of 1959:- A careful analysis of the
estuarine catch over the past ten to fifteen years gives an indication
of the possible adverse affect of closer settlement on adjacent lands
upon the productivity of these waters. For example, the commercial
production of bottom feeders like Black Bream and Dusky Flathead has
fallen considerably during this period. The wholesale denudation of flora
on the catchments and foreshores of coastal lakes and rivers for housing
settlement and horticultural and agricultural purposes is viewed seriously
by the Fisheries Authorities •.. The intense competition as development of
the State gains impetus makes it difficult to control this situation.
Creighton (1983a) discussed the changes in land use practice
within the Clarence catchment and, the implications for estuarine wetlands. The period post-World War II was described as the "mechanization
period". Over this recent period the development of a varied range of
mechanized equipment has allowed for the drainage and alienation of wetlands on an unprecedented scale. Pressey and Middleton (1982) discuss
the impacts of the flood mitigation works of this period upon the estuarine
biota. Numerous .other papers recount the changes to the estuarine environment that have occurred over the past thirty years (e.g., SPCC, 1979,
Dunstan, 1979: Pollard, 1979: Hodgkin, 1974, 1978: Lenanton, 1974,
Saila,1980: Chubb et aZ., 1981).
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No specific conclusion can be made at this stage of the discussion as to the aggregate impact of these changes on the N.S.W. estuarine
fishery. Based on the total catch data presented in Figure 2, the period
1960 to 1980 could be classified as representative of a stabilized
fishery (Kesteven's classification, 1971) - albeit at a much reduced level.
However, as discussed, total catch is but one factor of a series that should
be considered. Perhaps, for example, the total catch has increasingly
represented a greater proportion of the available stock. In such an
eventuality, the fishery may be classified as declining. To provide
further background for this investigation the following sections provide
data on the methods of capture and the regulations pertaining to the
estuarine fisheries of N.S.W.
Methods of capture
The methods used in the estuarine fishery have remained substantially the same during the period 1910 to the present. Methods employed
in the fishery are as follows:set-netting: the laying of a long gill net across a likely
area; these nets are fixed in position and left for varying
periods to allow moving fish to be entangled in the nets.
Laying, clearing and lifting of these nets is usually done by
one fisherman working from a flat-bottomed punt.
mesh-netting: the laying of a gil net in a semi-circular to
circular area; the fish are either scared into the net or,
by the use of two punts the net is hauled in, entrapping the
fish within the net.
beach-seining or hauling: a net is laid out from a beach or
back-net with both ends of the net brought back to the beach;
fishermen then haul the net into the beach or back-net,
trapping or entangling any fish in the net's path.
Trapping within estuaries is restricted to the taking of crabs the mud crab (Scylla serrata) and the blue-swimmer (Portunis peZagiaus) .
Prawn species, principally the school prawn (Metapenaeus macZeayi) and
the greasyback (Metapenaeus bennettae) are captured using pocket nets,
hauling and otter trawling. Otter trawling with the target being prawn
species is permitted within five N.S.W. estuaries (SPCC, 1979). No substantial by-catch of fish species is associated with otter trawling, with,
par~icularly the larger fish moving away in front of the leadline.
Trawling may, however, have had some impact on the fish and associated biota
of the estuarine fisheries. Possible adverse impacts include the disturbance of benthic flora and to a lesser, possibly minimal extent, fauna
(e.g., Gibbs, Collins and Collett, 1980), the raising of turbidity levels,
thereby affecting light penetration (this is particularly apparent in
shallow, muddy substrate lake areas such as Lake Wooleweyah, Clarence
estuary); the disturbance 'of fish affecting their movements and feedir.g;
and, the capture and subsequent death of juveniles and small non-commercial
species such as the herrings.
While the methods of fish capture remain substantially unaltered,
over the period 1900 to the present, equipment used has varied. Nets are
of synthetic fibre. Boats vary from the more traditional wooden punts and
- 12 -
tenders to aluminium punts. Outboards have now largely replaced the inboard motor, often in the past an adapted car engine. This has provided
fishermen with a greater degree of mobility, providing for a more
efficient use of the time available for fishing. It is believed that
this change may have substantially increased actual fishing effort.
The methods and the equipment used in the fishery parallel
the characteristics of a sustained and in some cases, a declining fishery.
Methods have converged on a set pattern with no substantial changes. At
the same time, there has been some improvement in the equipment used.
These are characteristics of a sustained fishery. Coincidentally, a lot
of the equipment is used beyond its normal life with capital investment
generally minimal. Additional to this, a very limited number of fishermen are entering the fishery, most fishermen actively engaged in the
fishery being so employed for the past twenty to thirty years. These are
characteristics of a declining fishery.
One of the most important tools for the management of fisheries
is that of legislation. Most fisheries legislation is designed to affect
the fishery directly, although, as welcomme and Henderson (1976) suggested,
it is becoming increasingly obvious that laws passed in domains other than
fisheries may also have far reaching consequences for the waters or the
fish stocks in them. It is recognized that the series of N.S.W. Acts
generally termed as 'environmental legislation' may do more for the fish
stocks of the estuarine waters than say, any move to control the mesh
size of the fishing gear used within these waters. For a review of some
of the legislation that is within this category, refer to Collett (1976)
or Creighton and Morgan (1982).
Legislation aimed at the estuarine fishery itself usually attempts
to control either the type of gear in use or some feature of it, or, to
restrict the fishery in time or in place. Limitation of the selectivity
characteristics of gear is enforced within N.S.W. Regulations dating
from the Fisheries Act of 1881 (with modifications in subsequent Acts)
restrict the mesh size used in both the scale fish and prawn fisheries of
the estuarine waters. Much of the theory underlining mesh selection by
size in gill nets has been shown to have somewhat dubious foundations
(e.g., Thomson, 1959a; Hamley, 1975). Concurrent with this regulation
of mesh size are regulations controlling the length of netting and methods
used. For example, in 1938, regulations were included within the Act to
restrict the lengths of hauling nets to less than 400 fathoms (Regulation
17). In 1942, this regulation was amended such that hauling nets could
not be landed by any method other than against a stake or back net (length
and mesh specified).
A further measure, acting complementary to the regulations of
mesh size and methods of capture is the declaration of minimal legal
lengths. These regulations were often formulated in the absence of any
data upon which an estimate of optimum catch could be based. As Thomson
(1950) stated, the criterion for establishing a minimum length was the
early conservationist precept of permitting a fish to attain a size at
which it would have spawned at least once before being captured. Aspects
- 13 -
such as sexual dimorphism and fecundity should be fully considered before
the implementation of such regulations.
The fishery is further restricted via regulations on place of
capture and effort. Certain waters are closed to commercial fishing on
the grounds that they are either spawning and nursery areas, or, so
confined that migrating schools of fish would be completely captured or,
were closed as a result of pressure from tourist and angling groups.
Regulation of effort within estuarine fisheries may be generally
seen to have as its principal objective the amelioration of the conflict
situation between professional and amateur fishermen, rather than actual
management of the fish resource. For example, while regulations for
particular waters and particular fisheries vary, it is generally the case
that professional fishermen are required to be off the water (or at least
tending nets in preparation to do so) by 9 a.m. Saturday •
The Senate Standing Committee on Trade and Commerce (1982)
commented at length on the nature and scope of N.S.W. fishery regulations.
Extracts from this report are as follows:- Until recently New South Wales
has been philosophically and fundamentally opposed to the need for
fisheries management. Fisheries administrators in that state have maintained that a resource will look after itself and that fishermen should be
allowed to fish it to a level which becomes uneconomic; fishermen will
move on to another resource giving the original resource time to regenerate and then will move back to it. Other State fisheries authorities
believe that attainment of the greatest economic return from fisheries is
best achieved by restricting the number of entrants to the fishery or
applying other management measures which are tailored to suit the biological and economic stability of the fishery ••• The attitude previously
adopted by New South Wales fisheries administrators is considered to
reflect a cottage industry approach towards the Australian fishing industry which is out of tune with contemporary attitudes and is regarded as
inappropriate for a national primary industry.
The Committee suggested that problems concerning Australian
fishery regulations and their lack of effectiveness in ensuring the management of fishery resources was the result of a series of factors. These
are as follows:conflict between States and between States and the Commonwealth;
the absence of a satisfactory working relationship between
the public and the private sectors of the industry; and
the paucity of fisheries research data and statistical information on which sound management decisions can be based.
Detail on the inadequacies of the statistical information collected on the
N.S.W. estuarine fishery are presented throughout this report. Recommendations as to alterations to the present methods of data collection
and the nature of data collected are presented in Part 2 of this report.
Principal species of the N.S.W. estuarine fishery
Pollard (1976) discussed the N.S,.W. fishery and the relationships
between estuaries and total catch. Using 'area of capture' as the criterion
- 14 -
for sub-division, Pollard presented three tables listing the following:species in which more than 50% of the total catch was taken
directly from estuarine waters;
species in which less than 50% of the total catch was taken
directly from estuarine waters;
species in which none of the catch was taken directly from
estuarine waters; and
distribution by area of capture for crustaceans and molluscs.
All data presented by Pollard was based on N.S.W. State Fisheries figures
for the years 1962 to 1972 (inclusive). Those species presented by
Pollard for which greater than 50% of total catch was captured in
estuaries are as follows:- River garfish (Hemiphamphus ardeZio), Shortbeaked garfish (Arrhamphus saZeroZepis), Dusky flathead (PZatyaephaZus
fusaus), Flat-tailed mullet (Liza argentea), Sand whiting (SiZZago
aiZiata), Sand mullet (Myxus eZongatus), Sea mullet (MugiZ aephaZus) ,
Luderick (GireZZa triauspidata), Bream (principally Aaanthopagrus
austraZis), Silver biddy (Gerres ovatus), Tarwhine (Rhabdosargus sarba) ,
Sea garfish (Hyporhamphus austraZis), Trumpeter whiting (SiZZago
maauZata) and the crabs, mud and blue-swimmer (SayZla serrata, Portunus
Other species described by Pollard as being also represented,
at least occasionally, in the estuarine catch are as follows:- Conger
eel (Conger verreauxi), Trevally (especially Caranx georgianus), Tailor
(Pomatomus saZtatrix), Mulloway (Argyrosomus hoZoZepidotus), Yellowtail
(Traahurus maauZZoahi), Slimy mackerel (Pneumatophorus austraZisiaus) ,
Yellowtail kingfish (SerioZa ZaZandi), Anchovy (EngravZis austraZis),
Sand flathead (PZatyaephaZus arenarius), Pilchard (Sardinops neopiZaharduB) ,
Snoek (Leionura atum), Teraglin (Atraatosaion aeqvidens), Morwong
(CheiZodaatyZus fusaus and GoniiBtius veBtitus)·, Snapper (ChrYBophrys
auratus), Australian salmon (Arripis trutta), Yellowfin tuna (NeothannuB
maaropterus), Southern bluefin tuna (Thunnus thynnuB maacoyii) and Skipjack
tuna (Katsuwonus peZamis).
As described by Pollard (1976), the juveniles of the first ten
of this latter group of species are common in the estuaries with the major
portion of the catch of most of these species taken in inshore and
estuarine waters. With the exception of snapper which spends a large
proportion of its juvenile life within estuaries, the remainder of these
species are generally marine and not normally dependent on the estuaries
at any particular stage of their life cycles.
A large proportion of the prawn catch is obtained in estuarine
All commercial prawns, with the possible exception of the Royal
Red prawn (H. sibogae), caught within N.S.W. waters are dependent upon
the estuaries for a major portion of their life cycle. Pollard (1976)
details area of capture for all prawn species as follows:- estuarine 39%,
inshore 17% and offshore 49%. Data contained within recent N.S.W. State
Fisheries Reports suggests that for the period 1968-9 to 1978-9, 38% of
the total prawn catch was obtained in estuarine waters. The estuarine
prawn catch is dominated by the school prawn (M. maaZeayi) and the greasyback (M. bennettae).
- 15 -
Thomson (1953) discussed the relationships between the sea
mullet catch and the total catch of estuarine fish. In the period of
Thomson's investigation, the sea mullet accounted for 35 to 46% of the
total N.S.W. estuarine catch. Thomson in his assessment of the condition
of the mullet fishery, noted the problems of using available data,
particularly with regard to effort and the range of species. For example,
wi~h regard to range, as Kesteven (1942) and Thomson (1953, 1963) noted,
the sea mullet of the eastern Australian seaboard forms one stock, the
local populations of which are regularly mixed by the periodic 'hardgut'
and spawning migrations. Consequently, in attempting to assess the
condition of the fishery it is necessary to consider the stock as a whole,
irrespective of state boundaries and of differing State controls.
Thomson found that fluctuations in the total estuarine catch
(N.S.W. and southern Qld) closely correlated to fluctuations in the sea
mullet catch. This correlation was not as obvious when the catches of a
particular estuary were investigated. Thomson suggested that local conditions, rather than factors common to the whole stock, determined the
level of catch in a particular estuary. These comments may be equally
applicable to several other species that pre-dominate in the estuarine
catch, but have a distribution range extending along the eastern seaboard and are known to spawn at sea (e.g., luderick, bream, sand whiting,
sand mullet). Other species such as the river garfish and the dusky flathead, for which all life history stages depend primarily on estuarine
habitats, may provide more applicable data for the examination of estuary
While features of the life history of particular species have
been alluded to in the above discussion, it is not thought relevant to
detail the life history features of all species prominent in the estuarine
catch. The reader is referred to SPCC (1981) for a listing of the life
history features of most of the species mentioned above. Life history
features for the prominent fish species of the Camden Haven fishery are
detailed in Section 3.
Relationships between estuarine and inshore/offshore
fisheries of N.S,W.
As alluded to in the previous discussion, Australian estuaries
are recognized as valuable nursery areas for many commercial fish species
(e.g., Pollard, 1976; Lenanton, 1974, 1977; Chubb et aZ., 1979, 1981;
Bayly, 1975). Similar comments are applicable for overseas estuaries
(e.g., Gunter, 1967; McHugh, 1967; Jhingran and Gopalakrishan, 1973;
de Sylva, 1975; Wallace and Van der Elst, 1975; Warburton, 1979; Clark,
1977; Shenker and Dean, 1979; Weinstein, 1979).
Recent investigations (Lenanton, 1982) have shown that, with
particular inshore environments, not all species could be regarded as
exclusively estuarine dependent. Lenanton's findings were based on
research in south-western Western Australia. Similar comments may be
applicable for inshore waters within the Great Barrier Reef (e.g., Olsen,
Dowling and Paterson, 1980). No similar findings are known to exist for
the high wave-energy coasts of N.S.W. and Victoria.
- 16 -
Studies on estuarine dependence within N.S.W. waters are limited.
The most detailed study was that carried out as part of the Environmental
Control Study of Botany Bay (SPCC, 1981). This report presented results
on a detailed investigation of the ecology of fish species within Botany
Bay and associated rivers. While the ecology of fish in this marinedominated environment may vary to that within a barrier estuary environment, their general classification of estuarine dependence is thought to
be applicable to the barrier estuaries of N.S.W. SPCC (1981) identified
four categories of estuarine dependence. These are as follows:species with all life history stages dependent on estuaries
for all their main ecological requirements;
species with all life history stages dependent on estuaries
for all their main ecological requirements except spawning;
species with juveniles dependent on estuaries for all of
their main ecological requirements, but with adults inhabiting
areas outside the estuary; and
species with adults dependent on estuaries primarily f
spawning, but with all life history stages typically fund
outside the estuary.
Additional to this, it was suggested that a further category could include
those species that were found to utilize estuarine habitats, but are
believed to be primarily dependent on inshore or offshore marine habitats
for all their ecological requirements. A list of species for each of
these categories is presented within Appendices 2, 3 and 4 of the SPCC
(1981) report.
This concept of estuarine dependence, defining to some extent
the relationships between the estuarine and inshore/offshore fisheries,
has important implications for land use allocation and management within
the coastal region. Given the high degree of estuarine dependence of
most of the commercial fish and crustacea species and assuming that the
fishing industry is both an important sector of the nation's economy and
an essential source of food resources, account should be taken of the
impacts of land use upon the estuarine and reverine environments. Impacts
from land use may be classified as being of one of the following types:changes in water quality - pollution and enrichment, e.g.,
industrial, agricultural and urban land uses;
changes in water quantity - both fresh and tidal flows, e.g.
dams, impoundments, irrigation, drainage and diversion
schemes, roads and bridges, training walls;
changes in the structure of the estuarine/riverine environment, e.g., sedimentation, infilling of wetlands and the
isolation of component areas by dams, impoundments, flood
levees, training walls and roads.
Such changes have, albeit in varying degrees, occurred within
all barrier estuary catchments of N.S.W. It is suggested that the aggregate impact of such changes may be best assessed by an examination of the
condition of the estuarine fisheries of the coastal catchments. The
following section describes those aspects that should be included within
- 17 -
an examination of the condition of a fishery. The section is concluded
by a description of the method chosen for the assessment of the Camden
Haven estuarine fishery.
Biological Monitoring at the Community Level - the
selection of suitable indices for an analysis of
estuary condition
Fisheries - methods and assessment
Section 2.2.1 of this report detailed and classified the condition
of a fishery within five discrete groupings - nascent, developing,
stabilized, declining and extinguished (after Kesteven, 1971). Char~c­
terist!cs Tepreae~tqtive of each of these particular categories were
detailed in-this discussion. Kesteven (1971) detailed various indicators
of the condition of a fishery and methods to ascertain their particular
significance. He suggested that indicators of condition could be grouped
within three general areas - technological, economic and resource-based.
This investigation is aimed at examining the condition of the
estuary rather than the condition of the fisher~per se. The condition of
the fishery in its general aspects ~>taken as aeiftg indicative of the
general condition of the a&~~aLitte environment which support9 ( the~ stocks.
For these reasons thO analysis ~based upon an investigation of the
principal species explo~ted in the Camden H~ven estuarine fishery, providing a review of each species' life history, the trends in yearly catch
and, the trends in effort generated to exploit these species.
As discusse~ by Thomson (1953) and Welcomme and Henderson (1976),
_ suoh-&n investigation ' is not simple. To provide adequate data upon which
to describe the condition of the fishery, information collected must
include data on the historical development of the fishery, social and
economic pressures acting on the fishery and, take account of the multispecies nature of the fishery. These aspects are included within the
To provide a basis for the assessment of the impact that changes
associated wi~and use practice may have had on the fishery, knowledge
of the land resource and it~ components, water quality and the natural
fluctuations in the environm~tal parameters that characterize the estuarine
waters are required. These data were detailed in Technical Reports I, 2
and 3 of this research project. Reference is made to the results of
these associated investigations in later discussion.
Estuary condition and estuarine fishes the selection of suitable indices
Table 1 presents the dominant species of the Camden Haven estuarine catch with an indication of the area of capture for each species.
Area of capture information is for N.S.W., displaying both Pollard ' s (1976)
data and, data for the entire period of available information - 1954 to
1979 (as documented within N.S.W. State Fisheries Annual Reports). The
s1ight discrepancies between Pollard's data and that calculated for the
- 18 -
Area of capture, fish species
Pollard (1976)
N.S.W. (195479)
River garfish (H. arde Lio)
Dusky flathead (P. fuscus)
Flattail mullet (L. argentea)
Sand whiting (3. ciliata)
Sand mullet (M. elongatus)
Sea mullet (M. cephalus)
Luderick (G. tricuspidata)
period 1954 to 1979 m
and by environmental
data. Within Part I
area of capture for each of the e
ecies ar
Comments describing the trends
apparent for each particular species are included within the text.
Of the seven species detailed within Table 1, the first three,
River garfish, Dusky fla~A~ and Flattail mullet are known to spawn within
estuarine waters of N.S.~~~ese species are believed to spawn within the
Camden Haven estuary (pers. comm. - professional fishermen). The life
history features of these species conform with the SPCC (1981) first category of estuarine dependence - species with all life history stages dependent on estuaries for all their main ecological requirements.
The remaining four species of Table 1 conform with the second
category of estuarine dependence, as defined by SPCC (1981)- species with
all life history stages dependent on estuaries for all their main ecological
requirements except spawning. Three of these species are known to spawn
close inshore - Luderick, Sand mullet and Sand whiting. Inshore spawning
may ensure the early arrival of eggs and/or larvae within sheltered estuarine
nursery habitats (SPCC, 1981). The remaining species, Sea mullet, is
generally believed to spawn in offshore waters. Offshore spawning maximizes
the opportunity for wider dispersal of the larvae along the eastern coast.
Given the spa~ing characteristics of these seven species, a
general categorization of populations is possible. This categorization is
as follows:Estuarine - River garfish, Dusky flathead, Flattail mullet;
Regionai - Sand whiting, Sand mullet, Luderick;
Eastern seaboard - Sea mullet.
- 19 -
The extent of the regional populations for each of the species grouped
within this category is undefined. Temporal variations in populations
and in biophysical factors such as inshore currents together with a lack
of knowledge on the behaviour of each of these species prohibits further
analysis. Similarly, the extent of the Sea mullet population will vary
with both fluctuations in population and biophysical factors (e.g.,
Thomson, 1953, 1955, 1963).
~, ho~(v~r, be inferred-&hat some indication of, estuary
condi tion can be gained via the study of catch rates for these species
Pro. idlilg that eRS factgrs affecting fishing eifoL L aLe quel1 Lifiect;
I' a
(III- t
corfaltion wtl:t, J!li ng=Qtlbe:
Inas i ge-Zleflecte d h~e cate
River garfish, Dusky Flathead, and pe. 1bl9 Flattail mullet, p&pulitioRG
~n Be regarded as largely distinct populations~
TReSE sp 188 may be particularly useful as indicators of estuary condition. The populations of ~~
all other species within a particular estuary will"to i la2~p ExL~, be ~~~ .
depe~d~nt on the carrying capacit~ of the estuary and thus,
, '~ !!~
cond~ bon'. Otht\r ~c~ors.,... ecb
. _ ~_e~ J'~.
degree of recruitlr6n~uven' s to 1;:he estuary (presnmably-mrt
fecundity usually e
s· ~high recruitment rate) and the environmental 'baseline' condi ~ons ~ithin the estuary.(tQ~~ aetors a~~antjfj~r~er
to Creighton (19a4) for a de~cription of €OE(se fact6rs ~ ~he
estuary). Wi hin this in estigation da"baJVaJJ,.ab1e--o a
the previously
listed species are pre ented. Th ~~~lofthis phase of the investigation is to dete~whi~h species, if Vany, may be regarded as indicat~~
of estuary condft'IOn.
FoJ-- ~ a.-.,f -k c.o .;U ,'''' ~ .... ~:.. •
l'J t{ c ;; I ~A
;t 5
IF,"~ f?t/~/
AS~OUS~, Mllti-species fisheries" are subject to fluc•
tuations and shifts in population structure and composition as a function
of both exploitation and prevailing environmental conditions. Heavy utilization may effectively eliminate the larger species, leaving those that are
smaller, faster growing and usually more efficient converters of primary
production. Acceleration in growth rate and a reduction in the size of
maturation of the exploited species may occur (e.g., Welcomme and Henderson,
1976). Eventually the relative population sizes will vary, with planktonic
and benthic feeders. d~minating th~ ~t~c#s, ....f.i!ih~y. l!ish cO~'K1t~~~~
~~.! _tj~.dergo s~m~la; changes when suSject to l~~ng ~i!A~ itoe 'rrom ~
Apo1 l..u.§Ilrl,·' enrichment !h"modifica'tion of the estuarine "i/vironment (e.g.,
ier and Henderson, 1973; Regier an
. ~
~ounted for~~n~~{~~
These/changes in community structure are
two mechdUism§. Firstly, the seven species previously
listed provide differences in both behaviour and food resources exploited.
By consideration of the catch of each of these species, general comments on
changes in community structure are po~le. Secondly, th~elative catch, ?-..-«"'
over time, for each of these species JIlT quantified. This l.o8 achieved ~~
the calculation of the proportion of total estuarine cat
ach of the
species over the period for which data~available.
his phase of t e
investigation has the objective of providing information on changes in community structure of the Camden Haven estuarine fishery - if any so exist.
~R'esLigaLieh v~a
To provide a context for
species and community structure of
consideratioll "",*86 QQ gjU9:g to the
history of the fishery, indications
4Z /tI. .
:uoi p
these investigations of the individual
the Camden Haven estuarine fis~
history of the fishery. ~~etajJjng h~
of fishery condition and the changes in
L. fI-!
- 20 -
methods and effort that have resulted
It was hoped at the wille of instigation of this investigation to
also relate tUe data collected to prevailing environmental conditions. Data
on prevailing environmental conditions was collected by this author over the
period 1980-81. Discussions were held with professional fishermen and a
questionnaire/log book circulated to all fishermen engaged in the estuarine
fishery. U~y, insufficient returns were received to allow for an
analysis of the impact of prevailing environmentat 'baseline' conditions on
. catch rates. Fishermen stated that, in the past, any investigation usually
meant further restriction of th~ir / ~S;iviti~S
~heir reluctance to cooperate ~nderstandable in ~l~ of t 0~1issues relating to estuarine
fisheries that are generally perceived by the public and by amateur fishing
9roups. Perceived issues, resulting in a conflict situation, hav~ often
been transferred into regulations via political action - in a lar~ numb~r
Qf cases without adequate recognition of the biological factors that govern
the resource base.
The method of investigation adopted for the Camden Haven estuarine
fishery, ha,Lassociated with it numerous inad~qyacies aqd deficieQCies. Horemost amongst these must 8e the following: - ~-.tt. - ....<--1<--~
Selection of species - Other species may provide a more representative indication of estuarine conp'~~ion. Unfortunately, data
not available
for a number of species that may~useful in such an investigation (e.g.,
Trumpeter whiting~ Greasy-backed prawn and Mud crab).
Fecundity, natural mortality and fotal population - Information on
these aspects for the species chosen 1s Incomplete. It hlle'I8 ehilot: no
estimate of the total population for a particular estuary is pdssible. Commercial catches will represent varying proportions of the total po~ulation
of a particular species for a particular estuary.
Area of capture - Information available on catch does not differentiate between particular areas of capture within a particular region. For
example, some of the Camden Haven based professional fishermen occasionally
work~ake Innes. Catches within Lake Innes were shown to fluctuate markedly
with environmental conditions (Creighton, 1983). Opportunist qarvesting of
this system varie~accordingly so that ~
t~ent of the ·contribution of
this fisq~... to the Camden Haven total caitCli ~ possible. Simila:t;ly, no
account ~:possible of the opportunist h rvesting of particular species
during spawning (and in the case of Sea ullet, ~ardgut) migration~. Catches
on the ocean beaches of the Camden Have region and included w~~hin the
Camden Haven catch need not reflect the 'ze and exploitation tate of the
local population.
Quantification of effort - No data
precise quantification of effort expended within the
These and associated factors are discussed fur~~Part II of
this re~r~uggestions for alterations to co~ten~;~h~d. of statistical s:~ 0 lection for estuarine '-s~i are included li~l}in :h:~ later
di""(' (
-~ .t. fo ~,j
~ PI "-- ~
t!>l .".
I.i£ ~ fi.--- /U~
- 21 -
J:i.!...s tor y of the Camden Haven Fi shery '\
Figure 3 presents the annual production (scale fish) for the
Camden Haven fishery (estuarine, inshore and offshore). rt 1S suggestea
~ 4fotal production to at least 1959 approximates the production from
the estuarine fishery. Data on total fish production is not available for
the period 1960 to 1~68 (inclusive). Sometime during this period the
development of offshore fi~hing methods and equipment allowed for increased
production from the offshore fishery. Estuarine catch over this period
generally declined. Peaks in estuarine catch during the early 1960s and
1970s correspond~to abnormally high catches of Sea mullet. ~
been aSSoei-ated wi;
tions in 'basel'
series of significant flood events occurr
Figure 4 presents an indication of effort ~or the Camden Haven
e s tua rine fishery. The figure is approximate, being composed of d~ ~~
various sources of varied acouracy. A large number of fishermen~a~ve
~ only temporarily employed in
h . fis
, with fluctuations in market,
eC0!J~c:. ,an
social factors
evance. For example,
the~iTOd ~ost-1930 saw an influx of unskilled persons entering the
f ishery in an attempt to gain a livelihood. A similar increase in effort
occurred following World War II. From 1956 onwards, total effort in the
estuarine fishery remained approximately stable, slightly decreasing as
long-term experienced fishermen retired from the industry. No indication
of time spent in the various sectors of the estuarine fishery is possible. ~
The £Q.llowipg BOilalieiltar~nd extracts t aken from N.S.W. State
Fish~ies An nu "] Rep01: tS p!I!'e uide urther data on the development, extent~
effort and me~h~PIOy ~ n '~~en estuarine fishery. ~
Prior to 1900" with no regular output for the catch, fishing waaJ
l imited t o providing for local needs . The following extracts describe the
north coast fishe ~ in general and the Camden Haven fishery in particular
f o r this period.
N. S.W: St ate Fis heri es Annu a l Report, 1885:
Fishing operations on
t he north coast continue, ,as heretofore, to be confined to the limited
s upply of local wants and to the production of small quantities of salt
fish, the latter work being mostly carried on by Chinamen, who send away,
consigned no their own countr~quantities of the finest whiting and
other fish. A few of our own fishermen occasionally take up the work, but
generally 'with indifferent results, though in one instance on the Richmond
River, salt
f~h was for a time regularly sent to Fiji .
During the winter months, June, July and part of August, fresh
fish was s ent t o Sydney from the Cl ar ence, Manning, Macleay and Hastings
Rivers, t he returns being good, and the fishermen only regret that the
opportunity did not continue.
N. S.W. St ate Fishe ri es Annua l Report, 1890:
Sea mullet made
their first appearances in the river [Camden Haven) on the 18th of March;
f-- ')
- 22 -
they were working their way up river against a strong fresh. Several
large schools of salmon appeared in the river on the 9th of September and
are still there. Whiting have been very scarce here until last month;
there is a fair store of other kinds of fish - bream, flathead, tailor
and jewfish.
There has been issued in Sydney for this river five yearly
fishermen's licences, and three yearly fishing boat licences, six halfyearly fishermen's licences and two half-yearly fishing boat licences.
Only 177 bushels of fish have been sent to Sydney market, on
account of their not being able to get them away to market in good condition. There is or have been three men fishing and cleaning them during
the last two months, but they complain of the irregularity of the steamer,
as they have lost several cases of fish and eels on account of the steamer
being delayed several times on the river. There has also been an average
of about ten baskets per week caught for local consumption.
N.S.W. State Fisheries Annual Report, 1895: Camden Haven cannot
be classed as a fish-producing water, on aocount of there being no certain'
communication with Sydney, the traders there being sailing craft only. It
is strange that while there is no trade done with fresh fish there is no
attempt at curing, for there are fish to be caught in abundance; and moreover, the finer kinds are very plentiful. No doubt the time will come when
this place will be used by fishermen.
In 1901 steamer trade was established with Sydney. This allowe~
for the development of the Camden Haven estuarine fishing industry:Regular communication with the metropolis is maintained by two steamers,
thus affording good means of transit. Net fishing is fairly remunerative,
the number of men employed being about twelve, and five boats.
N.S.W. State Fisheries Annual Report, 1901
Development of the industry was, however, still hindered by the lack Of;]
transport with at best, one steamer per week to Sydney. This reduced the
levels of exploitation of the fish stock, constraining the deve.lopment of,
the industry:The greater part of the fish captured consists of mullet of good size and
quality, which are netted in Queens and Watson Taylor Lakes. The steamer
traffic is irregular, otherwise a larger fishing population could be main'.
N.S.W. State Fisheries Annual Report, 1906
Approximately 29 men and ten boats were involved in the estuarine fishery
~6 with marked fluctuations in effort, as a function of availability of transport.
Documented impacts upon the Camden Haven fishery of the time
included sedimentation with a subsequent change in distribution of seagrasses (particularly the previously sandy oyster dredge beds of the
entrance channel) and the harvesting of mangroves for use in oyster cultivation. By 1909 most of the mangrove areas adjacent to the oyster cultivation areas of the Camden Haven had been harvested:-
- 23 -
I am informed that a motor boat has been supplied by the lessee (Mr J.F.
Gibbons) for the purpose of towing and collecting mangroves for' spat
catching. The heavy inroads made on this material has almost exhausted
the home supply, and in future long distances will have to be traversed
for suitable supplies.
N.S.W. State Fisheries Annual Report, 1909
Regulations were later formulated in an attempt to ensure the more efficient utilization of mangroves harvested for use in oyster cultivation. By
1938, experiments were being carried out to determine a suitable replacement for mangroves. By approximately 1950, the entire N.S.W. oyster
industry had adopted hardwood stakes as a suitable replacement for mangroves.
The estuarine fishing industry developed during the pre-World
War I period with the establishment of an iceworks in 1911. By 1915,
the North Coast Railway ensured the regular transport to Sydney market of
the catch. Effort during this period varied and was largely depend~nt on
the comparative return for effort from fishing and alte.cnL~i..ive a.t:ea"s 0':
employment such as forestry.
By 1919, the industry was well established with 32 men employed
in the industry. Two of these men were involved in offshore fishing for
lobsters and snapper, Equipment included 7 launches, 1 steamer (offshore),
11 boats and 5 punts. Methods used were principally meshing and hauling.
Hauling often involved the cooperative effort of up to ten fishermen. The
use of hand winches reduced the effort involved in this method of fishing.
Over the period 1920 to 1930 there was generally greater than 25,
but less than 30, men employed in the estuarine fishery. This was a period
of stabilization with some slight improvement in methods and equipment.
Expansion of the Camden Haven estuarine fishery did not occur during this
period as a direct result of the development of the offshore trawling
industry in the Sydney region. Comments from the 1926 N.S.W. State
Fisheries Annual Report on the impact of the development of the trawling
industry on estuarine fisheries of N.S.W. are as follows:I have frequently pointed out that the Trawling industry has not been an
unqualified blessing, seeing that it is crushing mullet from the market
and reducing the number of inshore fishermen operating.
Mullet has been the great standby of these fishermen, and it does not pay
them to capture the better class fish, which of course are not in such
prolific shoals, unless they can at the same time find a market for the
mullet. Deep-sea flathead is steadily capturing the publi0 taste, and the
catches of mullet are decreasing so that our figures disclose the fact that
the total catch of fish passing through the market today is little more
than when the inshore fishermen only were operating.
The reader is referred to the Annual Report of 1928 for a detailed evaluation of the aff.ect of the offshore trawling industry on the estuarine
The period 1930 to World War II saw a marked increase in effort
Camden Haven fishery with, by 1939, approximately 55 to 60 men
employed in the estuarine sector of the Camden Haven fishery. This period
also saw the development of fishing regulations limiting area and method
- 24 -
meshing nets in the entrance channel
of caPtur~ In 1933, the use
was prohibited. Haulin~ nets ere restricted to 400 fathoms length in
eens and Watson Taylor Lakes. In 1942, this
1938 for the waters of both
regulation was modified suc that hauling nets in Watson Taylor and Queens
any method other than against a stake or backLakes could not be landed
uld not exceed 25 fathoms of mesh not less than
net, the length of which
one inch.
The per/od following World War II saw the development of other- ,
sectors of th;t'dustry, particularly the inshore prawn fishery and the
offshore line
d trap fishery, with a subsequent reduction in effort in
the estuarine ishery. Fish stocks during this period were reported to be
declining throughout the estuarine waters of N.S.W. Decreases in catch
during this period were attributed to closer settlement and land clearing,
with the subsequent problems of siltation and pollution. Mullet production during this period was variable with market fluctuations, adverse
climatic conditions and a reported decline in stocks affecting the fishery.
Effort in the Camden Haven estuarine fishery over this period varied, with
a general trend of decline (refer to Figure 4).
The present Camden Haven estuarine fishery supports some 18 persons who are believed to be employed generally full-time in the estuarine
scale fish and prawn fisheries. As well as the normal regulations applying
to estuarine fisheries, area and method of capture within the Entrance
Channel, Gogleys Lagoon and Stingray Creek are stipulated. The Entrance
channel below the eastern entrance of Gogleys Lagoon is prohibited for all
types of fishing with the exception that meshing nets of a mesh throughout
of not less than 15 mm may be used for the capture of Mulloway. Fishing
by means of all nets is prohibited in Gogleys Creek entrance. Within
Gogleys Lagoon, the Entrance Channel and Stingray Creek fishing is prohibited by means of meshing nets except by the method known as splashing
during October to March
J.-:..- I'~
Discussions with local fishermen led to the following list of
comments concerning changes to the estuarine fishery and problems associated
with present p~Ges:)p • I_~·
f-- /
Fishermen suggested that there was a need for prawn size
regulation to restrict the capture of undersized prawns (often
sold as bait at a lower price) •
Beach hauling during spawning migrations requires regulation.
Fishermen suggested that a large number of men entered the
fishery temporarily during these periods, affecting the longterm catch of permanent professionals and resulting in market
Total populations of all fish species would appear to have
decreased in size, with meshing becoming an inefficient method
of capture. Setting is reported to be now carried out over a
longer period to ensure reasonable catches.
The training walls are believed to have altered the migratory
and estuary-recruitment patterns of the mullets, Luderick and
whitings. - ______________
Associated with the construction of the training walls , sand
shoals within the entrance channel have increased in extent.
- 25 -
Watson Taylor Lake has markedly reduced in depth on account
of siltation over the past thirty years.
Queens Lake would appear to have a denser coverage of benthic
flora than say ten years ago, with increased progradation of
the entrance channel sand spits.
Freshes within the estuary are now sudden and of reduced time
period. It was suggested that previously runoff persisted for
a longer period, with a subsequent longer period of brackish
conditions prevailing throughout the estuary.
These issues are discussed within Section 3.4 of this report.
Data pertaining to some of these issues was presented in previous Technical Reports (Creighton, 1982, 1984; Creighton and Morgan, 1982).
Catch and Life History Features of Selected Species
The following discussion presents detailed data on ~ Ie spe~ies
predominating in the Camden Haven estuarine catch - S~~, Flatta i l and
Sand mullet, River garfish, Sand whiting, Luderick and Dusky flathead.
Data presented includes a summary of the life history features, areas and
methods of capture, total catch - Camden Haven and N.S.W., seasonality
and comments on the apparent trends in the commercial catch. Additional
species are discussed briefly. Species included in this discussion include
school and Greasyback prawns, Trumpeter whiting, Yellowfin bream and the
Mud crab.
1980 to 1981
- 26 -
3.2. I
River garfish (Hemirhamphus ardeZio)
Life History Features:
The River garfish is found within the
estuaries of southern Queensland and N.S.W. It inhabits shallow, weedy
flats and ranges from the entrance of the estuaries to almost the tidal
limit. All features of the garfish's life cycle are achieved within the
estuarine environment. Spawning is believed to occur over the period
september to November. Eggs (comparatively large) are attached by means
of fine, hair-like filaments to the benthic flora of the flats which form
their normal habitat (Roughley, 1966). No information is available on
growth rates and seasonal movements within the estuaries. Thomson (1959d)
classified River garfish as a herbivore, reporting that Zostera sp. dominates their food intake. He suggested that diatoms and algaes comprised
less than 20% of their diet •
It has been suggested that River garfish may occasionally migrate
to adjacent estuaries. Virtually no information is available, however one
such incidence was reported for the Hastings River in the N.S.W. State
Fisheries Annual Report, 1909:-
unusual occurrence in connection with river garfish took place in July,
when a fair school of remarkably fine fish from 3 oz to 51 oz in weight,
a few sea fish interspersed amongst them, entered from sea, probably having
migrated from some adjacent river.
Further Information:
Roughley, 1966;
Thomson, 1959a,d.
Areas and Methods of Capture, Camden Haven:
Garfish are captured by
the use of small meshed nets either by beach hauling across seagrasses or
bullringing a school. Within Camden Haven, fish are captured, particularly
by bullringing, in Queens Lake (entrance area and channel area extending
to Herons Creek), Stingray Creek and the entrance channel. Commercial
catches peak in the mid-year, with significant catches from May through to
Catch for the Camden Haven,
Camden Haven and N.S.W. Total Catch:
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying figures. Catch for the Camden Haven
prior to 1953 represents all species of garfish. Given the composition
and relative catch rates of all species as available from 1953 onwards, it
is suggested that these data are representative of'the River garfish catch
(albeit slightly greater).
After 1952, catch of River garfish for the Camden Haven fluctuated
markedly. There would seem to be a trend of increasing catch over the
period 1959 to 1972 following a sharp reduction in catch in the years 1957
and 1959. Catch after 1972 has fluctuated markedly, however yearly catch
has never exceeded the maximum recorded catch in 1956 of 7.2 tonnes.
Data for total catch in ~.S.W. waters is available for the period
1953 to 1979. The total catch displays marked fluctuations with a maximum
catch in 1974 of 135 tonnes. Total catch has declined continuously since
1974 with minimum yearly catch of 19 tonnes in 1979. The maximum catch of
1974 corresponds to the maximum proportion of the catch captured in inshore
- 27 -
waters (20%). For all other years for which information is available,
greater than 90% of the catch was captured in estuarine waters.
River Garfish and Estuary Condition:
River garfish is a particular
target species requiring a particular net. No information is currently
available on effort. However, because of the particular method of catch,
it is suggested that information on effort may be easily collected. Noting
the seasonal abundance of River garfish and the recruitment to mature stock
and thus exploitation of stock during the middle portion of the calendar
year, it is suggested that catch statistics for each estuary should be
collected for calendar, not financial, years.
with respect to the Camden Haven, professional fishermen
suggested that the catch of River garfish reflected both market demand and
the abundance of the local population. They suggested that the local population has declined over the period post-World War II. The limited data
that is available supports this contention •
Because River garfish generally carries out all features of its
life cycle within estuaries, it may be an appropriate index of estuarine
condition. Data requirements for analysis of catch statistics with this
end objective in mind are as follows:Information on the carrying capacity and total population of
particular estuaries;
Further information on life history features (e.g., movements
and response to environmental 'baseline' factors);
Yearly description of market factors and their influence on
Alteration of the method of collection of catch statistics
to provide calendar year statistics for each estuary; and
Information on effort for each particular estuary.
If such data was collected, River garfish may provide an appropriate index
of estuary condition for a particular feeding type - the herbivores.
(Unditt.-ioted )
....,FLATHEADS ....... .
28 -
Dusky Flathead (PLatycephaLus fuscus)
Life History Features:
Features of the life history of Dusky flathead are detailed below. Most of the information presented is adapted
from SPCC (1981). This study detailed the ecology of various species within the marine-dominated embayment of Botany Bay and its associated
estuaries - Cooks and Georges Rivers. with a similar diversity of habitats
present within the barrier estuaries of N.S.W., it is suggested that the
results of the Botany Bay study are applicable, at least in general terms,
to the barrier estuaries of N.S.W.
over the Jllil-):iod D~er to April with peak in
February; sE-awning habita~is Zostera weed beds
within the estuaries;
Habitats of post-larva';~ smal~ juveniles:
grass, mangroves and shallow mud;
Habitats of large juveniles:
deep mud (winter);
Zostera sea-
deep mud and shallows (summer);
Habitats of adults:
Zostera seagrass (summer);
Zostera seagrass (winter);
deep mud and
Feeding type:
small size class - Macrophagic Carnivore (fish
and crustaceans); large size class - Macrophagic
Carnivore (crustaceans and fish) ;
Similar spawning periods as that detailed above have been documented for
the Camden Haven region (N.S.W. State Fisheries Annual Reports, 1903-1909;
Creighton, 1983). Thomson (1959c) tagged Dusky flathead in an attempt to
ascertain their movements in response to prevailing environmental conditions. He stated that there was no evidence of movement of flathead, in
Lake Macquarie, but noted that they were tagged and recaptured in small
numbers (13 returns over a three year period) .
Further Information:
Roughley, 1966;
Thomson, 1959c,d;
Areas and Methods of Capture, Camden Haven:
Dusky flathead are captured using the techniques of meshing and setting. Within Watson Taylor
Lake the main areas of capture are the sandy substrate channel areas
associated with Camden Haven ~nd Stewarts Rivers and the entrance channel.
Within Queens Lake the channel areas, particularly along the southern bank
associated with Stingray and Herons Creeks, provide most of the catch for
this lake. Commercial catches peak over the mid-year - April to July with reduced catches throughout the remainder of the year.
Camden Haven and N.S.W. Total Catch:
Catch for the Camden Haven,
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying figures. Catch for the Camden Haven
prior to 1953 represents the total flathead catch and includes the catch
of Sand flathead (PZatycephaLus arenarius). Methods of catch utilized in
the Camden Haven fishery of the time were not conducive to large catches
of Sand flathead - inshore trawling being virtually non-existent. It is
suggested that total flathead catch approximates the Dusky flathead catch.
Information available (N.S.W. State Fisheries Annual Reports) suggests
- 29 -
that virtually all the catch was obtained from estuarine waters. Maximum
total flathead catch for the period of available information was 27.4
tonnes (1945).
After 1952 catch of Dusky flathead initially increased from 6.1
tonnes in 1953 to a peak of 19.3 tonnes in 1955. Catches for all years
following except 1966 and 1967 were less than 13 tonnes. Where information was available (1950s to 1960s) virtually the total catch was
obtained from estuarine waters.
The trend of rapid decline then approximate stabilization
presented by the Camden Haven catch is similar to that detailed for Lake
Macquarie by Thomson (1959a). This may be simply the result of sustained
fishingeffortand, for that matter, increased amateur effort. Insufficient
information is available to confirm this, or to quantify any changes to
the total population that may have resulted from estuary condition.
Data for total catch in N.S.W. waters is available for the
period 1941 to 1979 (all years except 1943 and 1944). The overall trend
in total catch is similar to that for the Camden Haven. The N.S.W. total
catch displays a marked reduction in catch over the period 1941 to 1954,
with catch declining from 500 tonnes to 115 tonnes. Following this
marked reduction in catch, the yearly total catch appears to show cyclical
variations, ranging from 120 tonnes to 220 tonnes over a period of years.
Up until 1972 catch from inshore waters was generally less than 7\. Maximum proportion of catch from inshore waters of 20.5\ occurred in 1976. It
is suggested that the recent variations in area of capture may be attributed, at least in part, to the development of the inshore school prawn
fishery. During periods of significant fresh water discharge and low
salinities within estuaries, Dusky flathead may be significant in the fish
by-catch of the inshore School prawn trawl fishery. For example, this is
particularly apparent in the area known as the 'bullring' off the Clarence
bar. Catches of Dusky flathead by school prawn trawlers within the
Clarence estuary are generally insignificant.
Dusky Flathead and Estuarine Condition:
All features of the Dusky
flathead's life history are attained within the estuarine environment. It
has been suggested that Dusky flathead may move between nearby estuaries
(pers. comm. - N.S.W. State Fisheries). No documented occurrences of
such movements are known to this author. Further investigation is warranted.
Given the estuarine dependence of Dusky flathead, it may provide
a suitable index of estuary condition. Because Dusky flathead is a macrophagic carnivore and therefore comparatively divorced from the primary
production of estuaries when compa-red ~ River garf~~, analysis of catch
rates may be more complex than that for River garfish. Data requirements
for such an analysis include the following:-Information on the carrying capacity and total population of
particular estuaries;
Further information on life history features (e.g., movements
and response to environmental 'baseline' factors, growth
rates and movements between estuaries?);
- 30 -
Yearly description of market factors and their influence
on effort;
Alteration of the method of collection of catch statistics
to provide calendar year statistics for each estuary; and
Information on effort for each particular estuary. Complexities are associated with the collection of effort data
because Dusky flathead is often not the target species of
the inshore zone'. These resultant incidental catches comprise 'a significant proportion of the total catch.
Further investigation of these concepts and alterations to the
methods and content of statistical information collected for the fishery
is recommended .
1980 to
- 31 -
Flattail Mul let (Liza argentea)
Life History Features:
Flattail mullet are distributed throughout
southern and eastern Australia from Fremantle (W.A.) to Cooktown (Qld).
The species is most abundant within N.S.W. and southern Queensland.
Features of the life hsitory of Flattail mullet are detailed below. As
with the previous commentary on Dusky flathead, most of the information
is adapted from SPCC (1981). Similar comments on the applicability of
this data to barrier estuaries apply.
over the period October to June with peak in the
period February to April; spawning habitat is within the estuaries and possibly also inshore;
Habitats of post-larvae and small juveniles:
probably in a passive mode;
Habitats of large juveniles:
throughout the year;
upper estuary and river,
Habitats of adults:
seagrass and shallow sand (summer);
upper river and shallow sand (winter);
Feeding type:
small size class - Omnivore (insects and
algae); large size class - Herbivore/Detritivore
(detritus and algae) .
Thomson (1959b,c) provided an estimate of the total population of Flattail
mullet and detailed their movements within Lake Macquarie. He suggested
that Flattail mullet were continually on the move around the shallows of
the lake, generally within schools. The reader is referred to the
following list of reports and papers for further information on the Flattail mullet.
F" rt hec I 0 fornet I 0",
,Q,66, Tho~on, 1959:~C
Areas and Methods of Capture, Camden Haven:
Flattail mullet are
captured using the techniques of meshing and setting. A large proportion
of the catch is incidental to the main target species, Sea mullet,. Refer
to the later discussion on areas of capture of Sea mullet for detail on
specific areas. The commercial catch of Flattail mullet peaks in midyear over the period May to July. Significant catches may occur throughout the remainder of the year, though very limited numbers are captured
for the period November to February.
Camden Haven and N.S.W. Total Catch:
Catch for the Camden Haven,
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying
figures .•- No data is available on catch
for both Camden Haven and N.S.W. prior to 1953. The catches for both
Camden Haven and N.S.W. show marked yearly fluctuations. This may be
compounded by the present method of collecting data for financial years
rather than calendar years, presenting a distorted impression of the
actual yearly mature stock.
Maximum catches for the Camden Haven were in 1960 and 1974 (15.7
and 11.8 tonnes respectively). Catches for the Camden Haven of less than
- 32 -
2 tonnes occurred in the period 1961 to 1967 (inclusive) and from 1979 to
1981 (inclusive). Maximum total catch for N.S.W. of 492 tonnes occurred
in 1962. Minimum catch for the period 1953 to 1979 was 80 tonnes in 1979.
limited period of data available does not present any particular trend
in total catch for either the Camden Haven or N.S.W. No information is
available that allows for comment on the recent low levels of catch. It
should be noted, .however, that th~(.,marked reduction in catches is ~;~t
replicated by either the Sea or the Sand mullet catches.
Flattai I Mul let and Estuary Condition:
All features of the Flattail
mullet life history are attained within the estuarine environment. SPCC
(1981) suggest that Flattail mullet may, as well as spawning within estuarine waters, spawn close inshore. If so, dependent on the direction and
behaviour of inshore currents, this may.allow for the repopulation of adjacent estuaries. Further investigation of the spawning behaviour of Flattail mullet is required.
-'Flattail mullet, an omnivore, would complement Dusky flathead
(Macrophagic carnivore) and River garfish (herbivore) as an indicator of
estuary condition. Data requirements for such analysis are similar to
those previously listed for Dusky flathead, viz. carrying capacity and
total population per estuary, further information on life history features
- particularly spawning behaviour and response to 'baseline' factors,
calendar year statistics and information on effort (again complicated
because of the role of the incidental catch).
1980 to 1981.
- 33 -
Luderick (GireZZa triouspidata)
Life History Features:
Life history features of the Luderick, as
adapted from SPCC (1981), are as follows:Spawning:
over the period October to December with peak in
October; spawning habitat is the inshore waters;
Main period of recruitment to the estuary:
Habitats of post-larvae and juveniles:
probably in a passive mode;
Habitats of large juveniles:
October to
Zostera seagrass,
Zostera seagrass;
Habitats of adults:
estuarine channels, rocky reefs and
Z08tera seagrass/
Feeding type: small size class - Omnivore (algae an~ co:'epods); large size class - Herbivore (algae and
Thomson (1959d) suggests that filamentous algae dominates the diet of
Luderick. with respect to their movements, Thomson (1959c) suggested
that movement within Lake Macquarie did not form any particular pattern.
Four of the Luderick tagged by Thomson (1959c) were recaptured remote
from the lake - two in the Sydney region (Botany Bay and Port Jackson)
and two on the mid-north coast (Laurieton and Forster). N.S.W. State
Fisheries Annual Reports for the years 1903 to 1909 document the movement
of schools of Luderick adjacent to the Hastings entrance. Results are
summarized in Table 2.
Luderick movements, Hastings estuary
Passing Hastings entrance
Entering estuary
January, May
October, November
October, November
July to October
July, August, October
April, May, July, September,
April, May, September,
June, July, October, November
June, October, November
May, June, July, December
May, June, July, September,
Area and Methods of Capture, Camden Haven:
The entrance channel is
the main area of capture of Luderick within the Camden Haven estuary. Fish
are captured using the method of meshing (with splashing). Meshing and
- 34 -
setting for Luderick is also carried out within Watson Taylor Lake, particularly in the channel areas between camden Haven River and the entrance
channel. Some Luderick are captured by these techniques in Stingray Creek.
Virtually no Luderick are captured within Queens Lake. The Camden Haven
catch may also include Luderick captured in inshore waters using normal
beach hauling techniques. The commercial catch displays a seasonal peak
over the period March to July, with significant catches throughout the
remainder of the year.
Camden Haven and N.S.W. Total Catch:
Catch for the Camden Haven,
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying figures. Catch for the Camden Haven is
available for 1941, 1942 and from 1945 to present. Camden Haven catch
display~a marked decline in the early 1950s, with gradual recovery to the
maximum recorded yearly catch of 27 tonnes in 1971. All previously
detailed species displayed maximum annual catch in the 1940s. Since 1971,
the Camden Haven catch has been reduced, but still at least equal to the
catch of the 1940s.
N.S.W. total catch displays a somewhat similar trend to the
Camden Haven catch, with generally increasing catches over the late 1950s
and 1960s. Maximum catch of 880 tonnes in 1973 is slightly lower than the
maximum recorded catch of 900 tonnes in 1941. As with the Camden Haven
catch, annual catch has declined following the early 1970's maximum.
Luderick and Estuary Condition:
with the longshore movement of"
Luderick as previously detailed, the species is not suitable as a resident
index of estuary condition for a particular estuary. Catch of Luderick may,
however, provide some indication of conditions within estuaries. Later
discussion details the relative proportions of all species in the Camden
Haven estuary catch. Th!S'information, together with the data on Camden
Haven total catch of Luderick, suggests that conditions relevant to the
Luderick fishery have changed significantly" Increased catch of Luderick
and increased proportion of total catch may be attributed to one or both
of the following factors:a)
increased utilization of the total population;
increased carrying capacity of the Camden Haven estuary.
Creighton (1983) detailed the levels of enrichments (particularly phosphates and nitrates) entering the Camden Haven estuary. The levels of
these enrichments were considered to exceed natural levels. Sources
include fertilizers applied to agricultural lands and adsorbed to soil
particles which entered the estuary during significant erosive events,
and inadequate treatment of human waste, particularly via septic tanks.
Similar problems and resultant impacts on the fish biota have been
detialed for the Peel-Harvey estuary, Western Australia (Department of
Conservation and Environment, W.A., 1981). With filament~ algae dominating Luderick's diet, it is suggested that changes in water quality (and
thus the primary productivity of the estuary) may have allowed for enlargement of the total population of Luderick within the estuary. As with all
other comments on estuary condition made within this section of the report,
further information is required.
1981 .
- 35 -
Sand Whiting (SiZZago aiZiata)
Life History Features:
Sand whiting are distributed throughout
south-eastern and eastern Australia with the main area of capture being
central to northern N.S.W. and southern Queensland. Features of the life
history of Sand whiting are detailed below. As with previous commentaries,
most of this information is adapted from SPCC (1981).
Spawning: over the period February to April with 'peak in
February; spawning habitat is close inshore,
probably the surf zone and possibly also sand bars
at estuary entrances;
Habitats of post-larvae and small juveniles: shallow sand
and Zostera seagrass; probably in a passive mode;
Habitats of large juveniles:
shallow sand and patchy
Habitats of adults:
shallow sand;
Feeding type: small size class - Carnivore (polychaetes and
amphipods); large size class - Carnivore (polychaetes and crustaceans) •
Cleland (1947) details information on growth rates, spawning time and areas
of capture within N.S.W. and Queensland. He suggests that there is a
difference of some three months between spawning times, but that no raciation of the stock exists. Cleland contends that the lack of raciation is
due to the distribution of larvae and post-larvae by inshore currents
rather than any actual migration of juvenile or mature stock. Sources of
further information on the Sand whiting are detailed below.
Further information:
SPCC, 1981.
Cleland, 1947;
Thomson, 1959d;
Areas and Methods of Capture, Camden Haven:
Whiting are captured
predominantly by meshing (with splashing). Most of the Camden Haven catch
is taken from the entrance channel and Stingray Creek. Depending on
physio-chemical conditions, catches may also be taken from the sandy
channel areas of Queens and Watson Taylor Lakes. The commercial catch of
Sand whiting displays two seasonal peaks - autumn and spring (refer to
Figure 15).
Camden Haven and N.S.W. Total Catch:
Catch for the Camden Haven,
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying figures. The percentage caught in inshore waters displays a marked upward trend from the mid-1960s. This can
be directly attributed to the development of the inshore prawn trawl
fishery. It is not known whether Sand whiting's utilization of inshore
areas is primarily a function of physio-chemical factors associated with
river freshes or whether whiting utilize inshore areas for feeding throughout their adult life cycle. Given the reduced fluctuation in percentage
of Sand whiting captured in inshore waters compared to that for Trumpeter
whiting (Figure 22) it is tentatively suggested that Sand whiting may utilize inshore waters for feeding throughout their adult life cycle.
(Undi fferentioteel)
r---'" v " \_---'
\ .. .,,,\\
Estuarine -••••
- 36 -
Catch of whiting for the Camden Haven prior to 1953 includes
the associated species Trumpeter whiting (SiZZago macuZata). Figures
available for the composition of the Camden Haven whiting catch suggest
that Trumpeter whiting comprise, on average, less than 2.5% of the total
catch of whiting. Maximum catch of Trumpeter whiting for the Camden
Haven was 150 kg in 1960, comprising 8.5% of the total whiting catch for
that year. It is suggested that the total catch of whiting prior to 1953
approximates that for Sand whiting. Over the period, as for most of the
other species dominating the Camden Haven catch, the total catch displayed
a marked decline.
Catch of Sand whiting for the Camden Haven after 1953, while
displaying marked yearly fluctuations, is at best stabilized, possibly
increasing over rec~t years. To date, however, annual catch has not
exceeded the maximum yearly catch-.af-3.9 tonnes in 1945. The N.S.W. total
catch displays/a significant upward trend in total catch from 1953 to 1979.
This trend is replicated by the proportion of the total catch caught in
inshore waters.
Sand Whiting and Estuary Condition:
The lack of raciation detailed
by Cleland (1947) suggests that the inshore spawning of Sand whiting is
sufficient to ensure both a homogenous population and the recruitment of
post-larvae/juveniles to the estuaries of the N.S.W. coast. Sand whiting
catch may be useful as an indicator of conditions within N.S.W. estuaries
in total, rather than as an index of condition for a particular estuary.
The upward trend of total N.S.W. catch can be attributed to-the
following factors:Change in fishing methods have allowed for an increased
level of harvesting of the total population; and
I .
The increased harvesting of the mature stock has allowed fora greater proportion of juveniles to survive to maturity
(assuming food stocks are finite and fully exploited);
Conditions within N.S.W. estuaries have altered, thereby
allowing for increased populations of Sand whiting.
Information available suggests that all these factors may be of importance,
with the trend in the estuarine catch (dashed line on figure) replicating
that for the total catch.
It is suggested that Trumpeter whiting may provide a more useful indicator of estuary condition for particular estuaries. Trumpeter
whiting are known to spawn in the deep sand areas of estuaries (SPeC,
1981). Feeding characteristics of the two species are similar. Total'
catch of Trumpeter whiting for N.S.W. and the proportion caught within
inshore waters are displayed in Figure 22. Total catch for the Camden
Haven, where information is available, is also presented in this figure.
Information for the Camden Haven is insufficient for analysis.
The proportion of Trumpeter whiting caught within inshore waters
of N.S.W. fluctuates markedly. This may be attributed to the varying
physio-chemical conditions experienced within estuaries as a function of
Total catch
\ I
\ I
- 37 -
climatic variations. Both total catch for N.S.W. within estuarine and
inshore waters display an upward trend. It is tentatively suggested that
alterations to conditions within N.S.W. estuaries may have allowed for an
increased population of both whiting species.
Information is not available to confirm this hypothesis. Data
requirements necessary for such an analysis and to quantify the trends in
both whiting stocks are as follows:Information on the carrying capacity and total populations
of particular estuaries;
Further information on life history features (e.g., movements
and response to environmental 'baseline' factors, growth rates
and utilization of the inshore environment by mature stocks);
Yearly description of market factors and their influence on
Alteration of the method of collection of catch statistics
to provide information on particular age classes;
Information on effort for each particular estuary;
Information on changes to N.S.W. estuaries (e.g., changes in
configuration and quantity of sandy substrates as a result
of entrance training walls).
1980 to
- 38 -
Sea Mul let (Mugil cephalus)
Life History Features:
Sea mullet is found in the coastal waters
and estuaries of the tropical and subtropical zones throughout the world.
Thomson (1963) provides detailed data on the distribution and ahundance
of Sea mullet. Because Sea mullet is the dominant species in the N.S.W.
estuarine catch, a large amount of information is available on its life
history. The following summary presents a brief review of this information. Sources of further information are listed following the summary.
Spawning: over the period April to July with peak in April;
habitat is usually offshore, however there is some
evidence to suggest that M. cephalus may be able to
reproduce within an enclosed embayment (Creighton,
1983, reviews the relevant data);
Period of recruitment to the estuary:
June to October;
Habitats of post-larvae and juveniles: Zostera seagrass,
intertidal to supratidal areas - mangroves, reeds,
Habitats of large juveniles: seagrasses (summer);
estuary and river (winter);
Habitats of adults: river, estuary, ocean (summer);
and river (winter);
Feeding type: Detritivore/Herbivore (detritus, diatoms, bluegreen and green algae); main food items may differ
with ~t'!-J oN ~ ~
Sea mullet is estuarine dependent in that he major part of the life cycle
is spent in-coastat=±akes, rivers and bays, extending up-river to the
brackish and fresh portions of the rivers. A smaller portion of its life
is spent in inshore waters during various migrations (inclu~ing spawning. J/
migrations) .
~i~1 ~ d; ",~, ~ ,
Da~evf(., 1902;_~son,
~ (r,
~' ,.j.
Further information:
1950, 1953,
1955, 1959b,c,d, 1963, 1980; Chubb et al., 1981; Lenanton, 1982; and
additional reports and papers as'refe£eneed tcr~-tn these reports.
Areas and Methods of Capture, Camden Haven:
Mullets are captured
using the techniques of meshing and setting throughout the Camden Haven
estuary. Activities are carried out in ali areas of watson Taylor Lake
and associated creeks and rivers with backwater areas such as Bensons Inlet
and Dirty Corner being favoured locations. Within Queens Lake, as with
Watson Taylor, it is 'where you find them', however, the northern shore
near the entrances to Limeburners, Bobs and Waterloo Creeks are favoured
locations. Beach hauling is generally over a period of less than two
months' duration, centred on April to May. The fishery displays a marked
seasonality with Camden Haven catch greatest during the months February,
March, April and May. Significant catches are made throughout the remainder of the year.
Camden Haven and N.S.W. Total Catch:
Catch for the Camden Haven,
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying figures. Catch for the Camden Haven
- 39 -
prior to 1953 represents the total mullet catch and includes the catch of
s~nd and Flattail mullet.
Catch data after 1953 displays both the total
mullet catch for the Camden Haven and the Sea mullet catch. The close
correspondence between these two plots suggests that the total mullet
catch prior to 1953 approximates the Camden Haven Sea mullet catch. The
~s er~appears to be stabilized around an average annual catch in excess
of 120 tonnes. Recent catch rates, while below average, are not the
minimum recorded catch for the Camden Haven. Minimum catch of 35 tonnes
recorded in 1957.
Total catch for N.S.W. displays a decline over the period 1945
stable, slightly increasing annual catch over the period
Thomson (1953) discussed in detail the status of the N.S.W.
mullet fisery. Reference to Thomson's report and the problems of analysis
of total catch were detailed in Part I of this rePQ
For a arge part
the post- or ~-peri~d,-marxe
ac ors (e.g., gluts, quotas)
tly influenced the total catch of Sea mullet. As previously
suggested, re nt total catch may represent a larger proportion of thp.
tota popu ation. No detailed information is available, howevf'r indica.tions such as the removal of quota restrictions for the Clarence estuary
suggest that this may be so.
Sea Mul let and Estuary Condition:
Chubb et al. (1981) detail the
estuarine dependence of Sea mullet for the Swan-Avon fishery. From
extensive sampling of estuarine and nearshore locations, it was found
that the commercial fishery was based mainly on individuals that have
apparently never been at sea since the first few weeks of their life
when they entered the river system as recruits.
Insufficient data is available to allow for an analysis of
estuary condition based on Sea mullet catch. Most certainly, the drainage
of brackish swamps in the post-World War II period has reduced the carrying
capacity of the estuaries (e.g.' .~~~l953; Pressey and Middleton,
1982). Information required for
an analysis i~d
e ~ing:-
~on on th I arrying capacity and total population
of partiClI]af../stuaries;
description of market factors and their influence on
Alteration of the method of collection of catch statistics
to provide information on location of catch, method of
catch, and",age class .iet:: each l3aI"ticuJar
Coordination of statistics collected with Queensland and to
a lesser extent , Victoria;
Information on effort for each particular area of capture;
Further data on life history features such as natural mortality rate and behaviour in response to variations in
environmental 'baseline' factors.
Further investigation of these concepts and alterations to the
methods and content of statistical information collected for the fishery
- 40 -
Sand Mullet (MYxus elongatus)
Life History Features:
The Sand mullet is distributed from Western
Australia (approximately Fremantle-Swan estuary) to Queensland (approximately Maryborough). Thomson (1980) suggests that it is quite common in
estuaries throughout this range. Features of the life history of Sand
mullet are detailed below. As with previous descriptions, most of this
information is summarized from SPCC (1981).
Spawning: over the period December to June with peak in the
period December to February; spawning habitat is
close inshore; probably near the mouths of
Main period of recruitment to the estuary:
February to
Habitats of post-larvae and small juveniles: shallow sand
(> 81% sand) and Zostera seagrass beds, probably
in a passive mode;
Habitats of large juveniles:
Zostera seagrass beds;
Habitats of adults: shallow sand and seagrass (summer);
upper river including freshwater and shallow sand
Feeding type: small size class - Microphagic Carnivore
(micro-crustaceans); large size class - Detritivore/
Omnivore (detritus, algae and crustaceans).
Further information:
SPCC, 1981.
Roughley, 1966;
Thomson, 1954, 1959d, 1980;
Areas and Methods of Capture, Camden Haven:
Sand mullet are captured
within the estuary using the techniques of meshing and setting. As with
Sea mullet, beach hauling provides a significant proportion of total catch.
Catch, particularly within the estuary,maybe incidental to the main target species, Sea mullet. Refer to the previous discussion on areas of
capture of Sea mullet for detail on specific areas.
,Camden Haven and N.S.W. Total Catch:
Catch for the Camden Haven,
total catch for N.S.W. and percentage caught in inshore waters of N.S.W.
are displayed in the accompanying figures. No data are available on catch
for either Camden Haven or N.S.W. prior to 1953. The Camden Haven catcn
for which information is available displays marked fluctuations. It was
suggested to the author that, in some cases, Sand mullet may not have been
rigorously separated from the other mullet species. Actual yearly catch
is therefore suspect. Maximum catch recorded of 10.4 tonnes occurred in
1975. Annual catches as displayed, are generally much less, with for all
other years catch less than 5.2 tonnes.
The limited period of data available for N.S.W. suggests that
there has been an upward trend in total catch of Sand mullet. The peak
yearly catches do not correlate with the proportion caught within inshore
waters. The high yearly catches over the early to mid-1970s period may
relate to the flood events and brackish conditions within estuaries over
MUllET -
- 41 -
this period. Similar peaks are apparent within the Flattail and Sea mullet \
catches over this period.
Sand Mul let and Estuary Condition:
All features of the Sand mullet
life history except spawning, are attained within the estuarine environment. Inshore spawning may ensure both a homogenous population and the
recruitment of post-larvae/juveniles to the estuaries throughout the Sand
mullet's range. Sand mullet's feeding characteristics complement the
feeding characteristics of those species previously detailed. It is
suggested that further investigation of Sand mullet catch and the factors
affecting the catch may provide useful information on both estuary condition and the factors affecting the total population of Sand mullet
throughout its range. Data requirements for such analysis are similar to
those prevously detailed for other estuarine dependent species that spawn
in inshore waters.
Other SpewJes Significant Within the Estuarine Catch
the following:-
significance within the :stuarine catch include
Short-beaked garfish CA.
Yellowfin bream
CA. australis), Silver bfddy (G. ovatus), Tarwhine (R. sarba), Sea garfish (H. australis), Mud 6rab (8. serPata), Blue swimmer or Sand crab
(P. pelagicus), School pra~ (M. macleayi) and Greasyback prawn (M.
bennettae). All of these s~ecies, except Greasyback prawns, Silver biddy
and Sea garfish are generall~\believed to spawn outside the estuarine
environment, usually inshore.
The estuarine spawning species may provide useful indicators of
estuary condition for partiCUlar~stuaries. Problems in analysis include
the following:•
Quantification of effort - for example, Silver biddy and Sea
garfish are particular target species for which effort varies
Quantification of market factors;
Lack of knowledge on total
city of particular estuaries; ~
and the carrying capa-
Lack of knowledge on life history features such as the possible
movement of stock between nearby 'estuaries and the influence
of environmental 'baseline' facto1s on behaviour;
Presentation of data for financial\~ears - most species displaya seasonal abundance which, with the long period of
exploitation of the estuarine fish s~ocks, generally represents the catch of a particular age crass. For most species
(notable exceptions include the School\and Greasyback prawns)
this seasonal abundance correlates clos~r with calendar than
financial years;
Data on catch not available - for example, no data is.available on the catch of Greasyback prawns within estuaries.
1980 to
1981 .
1980 to
KO/ Month
- 42 -
Problems involved in the collection of such data include the quantification of recreational/amateur effort and the method of catch. Greasyback prawns may be a separate catch when hauling and pocket netting
techniques are used within estuaries. However, no separation of School
from Greasyback prawns, and for that matter, from other species such as
juvenile King prawns (P. plebejus) is possible for the estuarine prawn
trawl fishery. As for prawns, there is no separation within the data
recorded for crab species. It is suggested that the Mud crab, while
generally believed to spawn in inshore waters (e.g., Hill, 1982), may
provide a useful index of estuarine condition. Separation of the crab
catch into species and further investigation is recommended.
As with the previously detailed seven species, further investigation and the quantification of all these factors is recommended. Later
discussion (Section 3.4) details a suggested method for improvement in
collection and content of catch statistics for the N.S.W. estuarine/inshore fisheries.
Community Assessment
Fish communities appear to undergo similar changes when subject
to loading, whether it be from pollution, modification of the environment
or fishing pressure. In an attempt to provide some information on such a
phenomena, the proportion of total catch for the seven key species of
th~ Camden Haven fishery was-calculated.
Figure 19 presents this information and is based on yearly returns, as made available by the Laurieton
Cooperative. Comments on each of the seven species are as follows:River garfish:
Proportion of total catch represented by River
garfish displays a range of 0.5% to 10.5%, with a trend of increasing,
but fluctuating proportion of total catch apparent from the late 1950s to
present. This conforms with the ~ove general comments for a fish commu~subject to loading.
Proportion of catch displayed a maximum over
the period 1955 to 1957 far in excess of that for the following years.
Dusky flathead:
Proportion of total catch represented by Dusky
flathead displays peaks over the periods 1954 to 1957, 1966 to 1968 and
1978 to 1981. These peaks are progressively of reduced magnitude, with an
apparent trend of decline for all other years. Professional fishermen
reported that there has been a reduction in the average size of Dusky
flathead captured, so that recent years may represent a greater and younger
proportion of the available stock. No precise information is available to
confirm these claims.
Flattai I mul let:
The proportion of total catch of this species
displays marked fluctuations with a peak in 1960 (13.5% of the total catch)
and 1974 (9.1% of total catch). While the period of information available
is limited and in no way represents an indication of the natural stock,
prior to both exploitation and the alteration of estuary condition associated with land use practice, it is suggested that the data available
presents a slight decline in the Flattail mullet proportion of the total
Sand whiting:
In all years except 1957 (3.0% of total catch),
Sand whiting has accounted for less than 2.5% of the total catch. The
,\ nl
\ f\ II
f \
CATCH, 1940
(Undifferentiated )
~, \
\ I
(Undiffennlioled )
N.A.~ Lo
. .
"'- ~.
- '-I
\ I
, N.A.
. 1140
% Catch
- 43 -
proportion'of total catch would appear to be fairly stable around an
average of 1.5%.
Luderick is the one species of the seven spee4es
investigated which displayS~ marked increase in proportion of total
catch~maximum in 1971 - 16.2%)~
Average proportions for each of the
deca~s of available information are as follows:-
(7 years only)
It was previously suggested that the increase in proportion of total
catch may be related to enrichment of the estuary, thereby providing a
greater available food stock and thus a greater total popUlation of
Luderick wi thin the estuary. Other factors, as detailed previously, may be
of significance. Further investigation would be required to detenr.ine
the precise reasons for this shift in the proportion o~ the total catch.
Sea mul let:
Of all the species detailed, Sea mullet displays
the most marked fluctuations, from a minimum of 48.5% to'a maximum of 88%
of the total catch. Responses to environmental 'baseline' factors, the
variable availability of travelling schools on ocean beaches within the
region and market factors such as reduced demand during market gluts, may
be partly responsible for this marked fluctuation.
Sand mullet:
The limited information available on Sand mullet
catch suggests that there may have been an increase in the proportion of
total catch since the early 1970s. As previously detailed, factors
responsible for such a trend are not quantifiable without further investigation.
Figure 20 presents yearly catch per unit effort for the~seven
key species of the Camden Haven estuarine fishery. Catil~ is tile t'l5'tal
yeaY'.l:~~e=ma'rk:~et'I-v:ta-th~r~i-e~on=F.i6h,j,ng~Goo~e . Effort w,,4!.
t~ as ~ those fishermen licensed to operate within the Camden H~ven
Tl:1eee data were ohtaiRea fLum tTte ~~.
effort data is at best an approximation of real effort. Fishermen may move
from one sector of the industry to another dependent on abundance of stocks,
seasonality, market factors and so on. Additi.oniMl), eiome-f~e,
Et,t best,=,Bart;:;;,tim~B1m:.e=q__JJ!,,;9,.;-, beach",haul.ingc.CZ'.ews), ~~hout the
inaustry there exists a variation in experience and skill and actual time
spent fishing.
W _'-d..~
~ figure ~ that following a reduction in catch per unit
effort over the early to mid-1950s, there followed a period of increasing
then approximately stable CPUE with some slight decline in the mid-,to
late 1970s. While CPUE is generally taken as being indicative of the
condition of a fishery, this need not necessarily be so. Firstly, ~
detailed aee"e, available effort data is extremely inaccurate. Secondly,
if stocks are declining, fishermen will compensate, where possible, by
fishing longer. F~~~e, Camden Haven professional fishermen suggested
~:~ 31+.- , 11~ I)
54 56
78 80
- 44 -
that they are now setting for longer periods. Thirdly, market factors will
influence the actual effort so that if returns per kilogram caught are
reduced, effort will increase to provide a similar economic return.
Fourthly, CPUE does not provide any indication of the total available
population. For example, Kesteven (1971) suggested that, in a declining
fishery, actual effort and catch may initially increase, with subsequent
further impact on the fishery.
Given these inadequacies of CPUE as being representative of a
fishery, no conclusions on the condition of the fishery can be drawn from
these data. In the following discussion, some sugyestions are made concerning improved content and method of collection of catch statistics
which would, in the long-term, allow for improved assessment of the condition of estuarine fisheries of N.S.W.
3.4. I
Perceived issues - Camden Haven estuary fishery
A series of issues describing the changes to the estuarine
fishery, as perceived by Camden Haven professional fishermen, was reported
in Section 3.1 of this report. Comments on each of these issues in the
light of this investigation of the fishery and the previously published
reports in this series are as follows.
Sedimentation within Watson Taylor Lake:
Sediments of the Camden
Haven estuary were described and mapped within Technical Report 2 (Creighton, 1984). Changes in the pattern and quantity of sediments were noted
yia the inspection of avail?ble aerial photographs (1940 to present) .
- Within Watson Taylor Lake, "associated'~with Camden Haven and Stewarts River
deltas, sandy fluvial facies were observed to be prograding over muddy
lake bottom facies with sheltered areas that, in the 1940s, were intert~l now supratidal.
This report also provided data on light penetration
levels within the :estuary, providing information on the reduction in
light penetration associated with significant discharge events. From the
associated data on salinity, -.{t was concluded that the recovery period
from high levels of suspended solids was not related to tidal flushing or
to the destabilization of suspended colloidal material, but, rather, was a
direct result of sedimentation.
watson Taylor Lake was described in Technical Report 2 as a
settling basin for the waters of both the Camden Haven and Stewarts Rivers.
In an attempt to quantify the actual sediment loading in the estuary, data
available on water quality at Logans Crossing (above the tidal limit,
Camden Haven River) was reviewed within Technical Report 3 (Creighton,
1982) . , Based on available data for 1979, suspended solids loading on theCamden Haven estuary via the Camden Haven River was estimated at 540
tonnes/annum. Using the land resource and use appraisal data of Technical
Report 1 (Creighton and Morgan, 1982), it was suggested that the additional
input of suspended solids via the Stewarts River sub catchment would increase
this calculated annual loading by a factor less than 2.
These data suggest that Watson Taylor Lake may be infilling at
greater than 'natural' levels. To confirm this hypothesis, detailed analysis of bathymetric changes within Watson Taylor Lake would be required.
- 45 -
Bathymetric charts for Watson Taylor Lake, the entrance channel, Stingray Creek and Queens Lake are available from 1890 to the present. These
data, collected by the Department of Public Works, are difficult to
interpret because of the varied datum levels and transects used. The
method of investigation detailed by Bryant (1980) may be applicable for
such an analysis. Lack of time prohibited the inclusion of this method
of investigation within this series of Technical Reports.
Sand shoals within the entrance channel:
The location and configuration of major sand banks within the entrance channel would see~o
have altered little over the period 1940 to 1979. Actual variation in
volume of these sediments is difficult to quantify. Aga~n the method of
Bryant (1980) may be ap~licable. However, land use associated changes
would complicate such analysis. Changes over the past forty years include
modification of the entrance training walls, breaching of the river
training walls during flood events, dredging, both in the ocean entrance
and the estuary entrance channel, bridge construction and other lanQ ~US&­
associated changes such as the draining and filling of fringing wetlanus,
and the construction of oyster cultivation racks. All of these aspects
may have altered the tidal characteristics of the estuary, with subsequent
changes to the sedimentation pattern.
-Inspection of available aerial photographs and a ' review of
historical data suggests that the construction of river and entrance
training walls has assisted the transport of beach and nearshore marine
sand into the estuary. Refer to Druery and Neilson (1980), McLean and
Burgess (1975) and Neilson and Gordon (1980) for further discussion of the
mechanisms involved.
Nature of fresh water discharge and runoff:
Professional fishermen suggested that freshes within the estuary are now sudden and of reduced
time period, thereby reducing the period of brackish conditions throughout
the estuary. The impacts of land use on ~off patterns fO~J particular
catchment types are well d9cumented (e.g.fKuprianov, 1980; ~ Greenberg et
aZ., 1979; Loucks, 1975; \Branson, 1975). What is not well documented is
the changes that have occurred in water yield for Australian coastal catchments in association with land use changes.
For the Camden Haven catchment, data on freshwater discharge have
been collected for the Camden Haven and Stewarts Rivers since 1970 by the
Water Resources Commission of N.S.W. These data are described within
Technical Report 2. No data are available prior to 1970, such that no
comparisons between recent data and the catchment in 'natural' condition
is possible. Certainly recentJlischarge curves display sudden peaks with
the shape of the recession curves demonstrating the lack of prolonged
freshwater discharge. It is expected that changes in the characteristics
of the freshwater discharge have occurred, however no quantification of
such change is possible from the available data. The impact of these
changes (albeit extent unknown) on the biota of the Camden Haven estuary
are not quantifiable. Further data on the life history features of all
species, together with data on the changes to freshwa ' ~r discharge and
tidal flushing characteristics, would be required for such an analysi~.
The data provided by the Water Resources Commission, together
with the salinity and temperature data detailed within Technic~l Report 2,
may be useful for any later investigation of the impact of land use changes
- 46 -
on water quantity within the Camden Haven catchment. As noted within
Technical Report 2, it is recommended that such studies be carried out
for all the estuaries of the N.S.W. coast. This would allow for the
assessment of the impact of future changes in land use patterns on water
quality and ,quantity.
Benthic flora:
Professional fishermen suggested that there have
been changes in the distribution and density of seagrasses and algaes
throughout the Camden Haven estuary. Changes'noted are as follows:-
* Queens Lake - increased distribution
and'd~nsity of seagrasses throughout the lake with increased algal growth in
some areas such as the southern shoreline;
* Entrance channel - increased distribution and density of
Watson Taylor Lake ~ increased algal growth and reduction
in density and distribution of seagrasses.
Limited information is available on the changes in benthic flora within
the Camden Haven estuary. N.S.W. State Fisheries Annual Reports of the
late 1890s-early 1900s note the growth of Zostera sp. on oyster dredge
beds of the Camden Haven entrance channel. It wa~ s~ggested that this
growth was related to increased sedimentation within the entrance channel
with sandy substrate being replaced by a mud/sand mix.
Evans and Gibbs (1981) detailed the seagrass distribution and_i
abundance within Queens Lake and Stingray Creek. Their investigation
provides a frame of ,reference for future investigations of Queens Lake ...
Tech!1ical Report 3 (Creighton, 1982)/ of this series identified a point
so~ce of enrichment on the southern shore of Queens Lake - caravan park,
inadequate treatment of septic wastes. Algal growth was particularly
evident in the foreshore areas adjacent to this point source .. ,.This report
also-provided an 'j:!stimate, of iI>'resent levels of enrichments ,,'phos'phates and
nitrates, entering the, estuary from the upper catchment.
,.,' '-'. J
Technical Report 2 (Creighton, 1984) suggested that any~educ­
tion in the extent. and density of seagrasses within Watson Taylor Lake may
be related to increased levels of suspended solids. Certainly, those
areas of seagrasses remaining in watson Taylor are covered with fine
particulate matter and associated algal growth.
It was noted in Sections 3.2 and 3.3 of this report that changes
in the fish population, as indicated by total catch and proportion of
total catch, ~ be related to changes in the benthic flora of the estuary.
Particularly, the recent increase in proportion of total catch of Luderick
and River garfish may be related to, among other factors~"changes in flora"
within the estuary.
Total population:
Professional fishermen suggested that the
total populations of all fish species would appear to have decreased in
size, with meshing becoming an inefficient method of capture. Setting is
reported to be now carried out over a longer period to ensure reasonable
catches. Amateur fishermen also suggested that there has b~en a decline
in fish stocks.
- 47 -
While recogn~z~ng the limitations of yearly catch as an indicator of total population, rt~should be noted that for Dusky flathead,
River garfish, Sand whiting and Sea mullet, there has been a distinct
decline in total yearly catch over the period early 1940s to present.
Data available is limited such that no specific conclusions 2an.be made
for these species or, for that matter, for the other species that predominate within the Camden Haven estuarine catch.
Aspects that may" effec.t/the carrying capacity of an estuary
include light penetration, )'-i)h1s'i~al chemistry, 'extent of estuarine wetlands, fishing effortcand_the hydrological regime. Present light penetration levels, physic'af 'chemistry and 'the hydrological regime of the
c~mden Haven estuary were detailed in Technical Report 2. As previously
noted, no quantitative conclusions can be made concerning changes to these
attributes. Fishing effort has been substantial since the early 1900s.
Again, because of the lack of d~ta no specific conclusions can be made .. ,/,
I ,
' ..
J •
With regard to estuarine wetlands, Technical"'Report 1 (Creighton
and Morgan, 1982) mapped and described the estuarine wetlands of the
Camden Haven. As was noted within this report, most of the brackish
estuarine wetlands on riverine alluvium have been disturbed, generally
drained for agricultural purposes. Additionally, areas of mangroves and
salt marsh such as those on the southern side of the entrance channel,
have been effectively isolated from the estuary by roadworks. Presently
available information on the function of estuarine wetlands is limited.
To this author's knowledge, no studies exist which accurately relate the
extent and the alteration of extent of estuarine wetlands to the carrying
capacity of an estuary.
• Training wal Is and fish movements/behaviour:
Professional fishermen hav~ suggested that the training walls may have altered the migratory
and spawning patterns of fish species.' Certainly, the construction of
training walls on most N.S.W. barrier estuaries has reduced, often obliterated the extensive sand shoals and channels that once characterized their
entrances. This may have had some impact on those species that spawn in
the entrance inshore area, particularly the whitings and the Flattail
and Sand mullets. No research .on this aspect of fish behaviour is known to
this author. Secondly, it is well established that training wall~Jalter
the localized current patterns of the barrier estuary entrances.' As to
whether this has influenced the migratory behaviour of such species as Sea
mullet and Luderick, no informationi~'available.
Beach haul ing - the need for regulation:
Professional fishermen
suggested that beach hauling requires regulation. They suggested that ~
large number of men entered the fishery temporarily during these periods,
affecting the long-term catch of permanent professionals and resulting in
market gluts. This, in the author's experience, is a common complaint of
estuary fishermen of the N.S.W. coast. With regard to Sea mullet, it is
not at present known what proportion of spawning stock actually re-enter
estuaries following their spawning migration (e.g., T\lomson, 1960).
Research on this aspect would be required prior to formulating any regulatory changes to the present methods of catch. It is suggested, however,
that the concept of restricting effort to those permanently employed is
worthy of immediate consideration by the relevant authorities.
48 -
The previous discussion has detailed the perceived issues facing
the Camden Haven estuarine fishery as they relate to the data collected
by this study. The following section evaluates commercial catch statistics
as indicators of estuary condition. Foremost among the problems of such
an ~pproach is the lack of relevant data on the commercial catch. Suggestions for revision and alterations to the data collected on estuarine
fisheries completes this discussion.
Estuary condition and N.S.W. catch statistics
Because of the nature ~f the statistical data available, very
limited definitive information is provided by the previous analysis on the
pondition of the Camden Haven estuary. As detailed within previous sections,
there has been a marked reduction in the total catch of some species,
principally River garfish, Dusky flathead and Sand whiting. The total
catch of Luderick displayed a similar reduction with recovery in recent
years to previous levels of catch. For species such as Flattail mullet,
Sand mullet and Trumpeter whiting, the time period of information available is not sufficient to allow for any precise conclusions concerning
changes to the total catch.
Similar comments can be made concerning the previous attempt at
community assessment. For the Camden Haven there has been a distinct
increase in the proportion of catch for Luderick, River garfish and Sand
mullet. A decrease is apparent for Dusky flathead and Flattail mullet.
However, information is insufficient to precisely define the nature and
reasons for these apparent trends.
Inadequacies in the information available have been 'previously
listed for each particular species. It can be concluded that the statistical information presently collected does not allow for any detailed
analysis of the ecological nature of the estuarine fisheries of N.S.W ..
Such a conclusion was reached by Thomson (1953) within his analysis of
the status of the East Australian Sea mullet ~ishery. Similar comments
concerning presently collected statistics are contained within th~PQrt
of the Senate Standing Committee on Trade a'11 Commerce (19821...' This investigation has, hQwever,' identified som~vproblems and inadequacies in
the nature, content and methods of data collection for the N.S.W.
estuarine fishery. The analy.sis has also identified some areas where
further research is required. suggestio~s for revision and alteration
to the data collected on estuarine fisheries, together with some suggestions for further research, ~re presented in the following section.
N.S.W. statistics - suggestions for alterations
to method
and content of data collected
It is suggested that data content and collection methods for
N.S.Wi estuarine fisheries be revised to provide more detailed info;rmation
on both the ecologic and economic aspects of the fishery. Aspects
requiriug inclusion in such a revised system include the follow±ng:Area of Capture:
Information in N.S.W: Sj;a,te Fisheries Annual
Reports is presented according to a series of 'fishing districts'. These
districts are effectively an agglomeration of coastal lagoons and
- 49 -
estuaries for a particular region. For example, as ~his sLudy-fias shown
(Creighton~3), catch from the Lake Innes-Cathie lagoonal system is
included either within the Camden Haven or Hastings District, dependent
on which Cooperative handles the catch. Similar comments apply to other
coastal lagoons and some of the smaller barrier estuaries (e.g., Nambucca,
Bellinger Rivers) of the N.S.W. coast. It is suggested that catch information for each particular estuary/lagoon/embayment be retained by use of
a data storage system with summaries of this information included in N.S.W.
State Fisheries Annual Reports. For some of the larger systems such as
the Clarence estuary, further delineation of area of capture may be useful. Similarly, data on catch inshore by beach-hauling techniques should
be collected and stored for appropriate regions. Data on by-catch from
such as prawn trawling inshore should be collected for these areas, with
separation of catch data based on the method of catch.
Effort and Catch Data:
The data provided on effort by the number
of licences issued is virtually useless in any assessment of the condition
of a fishery. Similarly, there are numerous problems with catch data
provided by fishermen'S monthly returns. It is suggested that improved
effort and catch data could be provided via the assistance of Fishermen's
Cooperatives. It is proposed that the present system of fishermen ' s
returns be abolished and be replaced by data collection at point of landing. A form, to be completed by Cooperative staff with the assistance of
fishermen whenever catch is weighed-in could include the following information:- area of capture, method used, target species, weight of catch
(by species), number of crew and time spent fishing. Some account may
have to be taken of aspects such as holding of catch (e.g., by prawn
trawlers). This could be incorporated within the format of the data ~­
l~ion method.
It should be noted that this data collection method will not
necessarily account for unsuccessful fishing trips, nor will it account
for private sales. The problem of recreational catch should also be
noted. For some species, recreational effort can be regarded as inconsequential (e.g . , mullets, River garfish). However, for species such as
Dusky flathead, Sand whiting, nream and Luderick, some account of recreational effort is CGASidezed necessary. Further investigation of these
problems is recommended.
Seasonal ity and Age of Catch:
Estuarine fisheries are generally
exploiting a particular age stock. This is mo~t defi~tely the case with
species such as prawns, River garfish and gen~fally the mullets and
whitings. It is suggested that any summations presenting yearly catch
should take account of this factor and present information accordingly.
For example, yearly catch based on the financial year is applicable for
species such as School prawns. For most of the estuarine fish species,
the calendar year provides a more appropriate delineator of age of stocks
(and thus the influence of such factors as pree~environmental 'baseline' fluctuations). To complement this aggregation of catch into yearly data,
it is suggested that routine examination and ageing ar-marketed fish be
effected. Division of a monthly sample of the fish cBtch from particular
estuaries into appropriate size classes would provide sufficient data for
these purposes.
'Regional' Stocks:
As discussed previously, ' several of the
species predominating in the N.S.W. estuarine fishery are part of at
- 50 -
least regional stocks that are also captured in Queensland and/or victoria (e.g., .Sea mullet, ,Sand mullet, tuderick,Jand whiting). It is
suggested that cooperation with.th~ r!;!Jevant agencies in these States
is required to provide an indication of total catch and effort. The
adoption of a uniform method of data collecti~ 'is considered worthy of
detaiied cooperative investigation.
Further Species Del ineation - Crustaceans:
I~is suggested that
further species delineation may be appropriate for the crustaceans.
Delineation of crabs into particular species may provid~useful information on both stocks and estuary condition. with regard to the prawn
species, it is difficult to envisage how any separation of .School from
Qreasyback prawns can be effected. Certainly, these species" can be
(easily sepaFated from mature King and Royal red prawns. Delineation, at
least to this extent, is recommended •
• Environmental 'Basel ine' Factors:
The c~ction of data on particular age classes will provide some information o~the influence of
environmental 'baseline' factors on the total stock and catr.h rates.
Complementary data on variations in these factors, at'least in a qualitci.tiv~ fe~ is necessary.
For example, data on freshwater discharge to
estuaries is routinely collected by the N.S.W. Water Resources Commission.
Similarly, salinity and temperature data are collected for at least one
point for all the oyster producing estuaries of N.S.W. (e.g., Wolf and
Collins, 1979). It ~~'applicable ,tq extend the collection of physiochemical data of estuaries to include associated parameters such as light
penetration, (secchi disc; and to extend the points of data collection to
provide representative data for the various sectors of each estuary/
lagoon/embayment. Associated with this extension of routine data collection, it is suggested that the 'Estuarine Environment and Resources
Programme' conducted by N.S.W. State Fisheries may need to be enlarged to
incorporate further data collection on aspects such as seagrass distribution (e.g .•,/E-Ga:ns and Gibbs, 1981)~ov1:de ~arly summaries of
conditions w:H=hin estuaries as they influence"both juvenile and mature
fish stocks.
Market and Economic Factors:
Market factors and the analysis of
trends in capital investment within a particular fishery are important
attributes in any analysis of fishery condition. It is suggested that
various aspects providing information on these factors be collected either
monthly or yearly, as may be applicable. For example, the yearly collection of data on boats and equipment for a particular estuary and/or
fishery could be collected by the relevant Fishermen's Cooperatives. This
information, together with a monthly summary of market factors as they
influence effort and Cooperative operations, would provide useful data for
fishery assessment. These data could be stored using appropriate techniques~summarized within N.S.W. State Fisheries Annual Reports.
The summation and presentation of all the.above information,
together with information on the other fisheries of N.-Ef.w., requires
detailed appraisal by the responsible agencies. It is suggested that the
Annual Reports of N.S.W. state Fisheries should provide information on
each particular fishery in separate sections. Each section detailing a
particular fishery could be further subdivided into ecological and economic
aspects. The presentation of data in this fashion would facilitate the ongoing appraisal and management of each particular fishery.
- 51 -
The results of investigation for each particular specie~ provided comments on areas of research that would assist the analysis of
both fishery and estuary condition. Areas of research worthy of further
investigation include the-foTluw±ng~Fish movements - for all species in response to environmental
'baseline' factors; between estuaries for species such as River garfish,
Flattail mullet and Dusky flathead; and the extent of 'regional' populations of species spawning inshore.
Population assessment - total stock for all species;
carrying capacity of particular estuaries/lagoons.
and the
Life history features - further information on natural mortality
for all life stages of species; information on growth rates, spawning
behaviour, fecundity etc.
Influence of man-induced changes on species and popUlations - for
example, training walls and other entrance altering mechanisms su~h as
the artificial opening of coastal lagoons, sedimentation, alienation of
wetlands and changes in water quality and quantity.
Information provided by research into these aspects would facilitate both the management of the fish and crustacean resources that the
N.S.W. coastal region provide~ an~the allocation and management of land
uses within the coastal catchments.
- 52 -
4. I
The Sydney Rock Oyster (Saaeostrea aommeraialis) and
Estuary Condition
The Sydney Rock Oyster may provide an indication of estuary
condition via fluctuations in production and by the analysis of the
quality of the oysters themselves. Firstly, it is evident that oysters
must have the proper environment in order to multiply and be marketable.
water depth, temperature, salinity, turbidity and quality must conform to
the narrow range of oyster growth requirements and sanitation. All of
these conditions are affected by man-made changes in the environment pollution, enrichment, dredging and filling, alteration of wetlands and
engineering works that offset tidal flushing, water circulation ond sedimentary patterns. An analysis of commercial production rates may provide
some indication of the overall condition of a particular estuary.
Secondly, oysters may provide valuable information on actual
water quality. Oysters are filter feeders; they filter out food and oxygen from the water they take in and circulate out. This traps plant
plankton used for food, but bacteria, viruses, metals and pesticides are
also trapped and concentrated for they are not circulated out after the
water has been filtered.
4. I. I
Factors Affecting Total Production
Aspects that affect production rates include the following:-
Effort and Methods of Cultivation:
Changes in total production
as a result of fluctuation in effort will involve a time lag of some 2 to
3 years, dependent on the cultivation methods employed and the particular
estuary involved. Recent advances in artificial cultivation techniques
(e.g., Wisely, 1980, 1983; Holliday, 1983) have effectively reduced cultivation periods and allowed for increased production rates. Developments
presently in progress such as hatchery spat production and artificial fattening in ponds (e.g., Nell, 1983) will further increase production, as
well as reducing the dependence of cultivation techniques on the condition
of the estuarine environment.
Natural Predators:
Oysters are subject to heavy mortality
during the larval and soft-shelled phases. Many larvae die because of
unfavourable environmental conditions. For example, the decline of the
dredge beds relates, in part, to the loss of a suitable substrate upon
which the larvae may attach - sandy sediments having been overlain by
muddy sediments. Predation also takes a heavy toll of the larvae and
newly settled spat. Predators of oyster larvae include the mullets.
Oyster spat are included within the diet of such species as Yellowfin
bream and Tarwhine. Growing hard-shelled oysters are part of the food
crop of stingrays and Mud crabs. Welks and starfish also rely on oysters
for a portion of their diet.
- 53 -
The mudworms (Boaaardia and PoZydora sp.) present a particular
problem, in some cases markedly reducing production rates. Heavy infestations of mudworms cause the oyster to loose condition. The worst
feat;re of mudworm infestation is that the shell blister is easily
broken when the oyster is opened and the mud released from the blister
detracts from the appearance and taste of the oyster.
Research by Skeel (1977) found that worms subjected-bo continuous salinaties of 15 to 20% stopped reproducing, died young and spent
much less time feeding than worms kept at 25 to 30% salinity. Further,
silt load in-water was found ··to be an important factor in the development
of mudworm infestations. For example, no mudworm is found in the Wagonga
Inlet ,:;'wh~~eas in the Manning River, Tuross Lake and the Camden Haven, where
the silt loads are or have been heavy, worms can be a serious problem.
Mudworm was first noticed in the Camden Haven in 1896, appearing in problem proportions in the late 18905, early to mid-1920s, mid-1950s and in
the early to mid-1970s.
Microorganisms such as the diseases known as Winter Mort;ality
and QX can all but decimate a particular crop. A severe outbreak of
'winter mortality' has been known to destroy up to 80% of the marketable
crop (e.g., Malcolm, 1972). Heaviest mortality is normally in the largest
oysters. Cold water temperatures and high salinities appear to be
associated with a high incidence of the disease. Winter mortality has, to
date, not been a problem on the Camden Haven estuary.
QX (Haplosporoidian - MarteZZei sydneyi) would seem to be
related to hydrology, particularly freshwater discharge and water quality.
Experiments by the author suggests that the cumulative effects of land use
practice may be related to the mortality rates of this disease (Creighton,
198]a). As evidenced by regular testing of oysters by N.S.W. State
Fisheries over the preceding two year period, this disease would seem to
be 'spreading' southwards, with QX evident within the Macleay estuary in
1983. QX has not yet been encountered in the Camden Haven.
'-'. F I uctuat ions In Env I ronmenta I 'Base I I ne' Cond I t Ions:
High temperatures and flooding may cause oyster mortality. During summer, because
of high temperatures, mortality is common and severe killings can occur
when low tides expose the oysters for long periods on excessively hot days.
Immersion of oysters in freshwater for several days is not injurious, but.
exposure to freshwater for long periods, as can occur during flooding,
causes high mortality.
Man-associated Changes to Estuary Condition:
The above factors
affecting production may be aggravated by 'changes to the estuarine environment which places the oyster under 'stress'. The concepts of synergistic
effects on oysters has yet to be fully researched. Evidence available
suggests that problems may be substantial (e.g., Ward, 1982). Some obvious
areas of concern include changes in estuarine hydrodynamics, soil erosion
within the catchment and wetland alienation. For example, changes in
estuarine hydrodynamics associated with engineering works may increase
the sediment rates in particular areas, thereby smothering oysters,
reducing feeding rates or increasing the prevalence of mudworm. Increased
sediment loads on the estuary as a result of soil erosion will result in
similar problems. Wetland alienation may reduce the available food for
- 54 -
the oysters (e.g., Dunstan, 1977) and alter estuarine water quality and
Other problems include the alternative, often conflicting, uses
for a particular waterway, thereby reducing the available area for oyster
cultivation. Bacterial and chemical contamination may lead to a substantial reduction in market demand. The problems of bacterial and chemical
contamination are detailed in the following discussion of the use of
oysters as an indicator of estuarine water quality.
Section 4.2 details the history of harvesting and CUltivation of
oysters within the Camden Haven estuary. This discussion is accompanied
by Figure 23, which presents annual production for the Camden Haven,
together with comments on production effort and the factors that have
influenced total production.
Oysters and water qual ity
Research towards the application of bivalves as indicators of
water quality are well documented (e.g., Thomson, 1979, 1983; Harris,
Fabris, Statton and Tawfik, 1979; Klumpp and Burdon-Jones, 1982; Ritz,
Swain and Elliot, 1982; Wotton and Lye, 1982; Read, Anderson, Matthews,
Watson, Halliday and Shiells, 1982; Plusquellec, Beucher and Legal, 1983).
Actual investigations involving S. commerciaZis are limited. with regard
to heavy metal contamination, the work of Mackay, Williams, Kacprzac,
Kazacox, Collins and Auty (1975) and SPCC (1979b) are the only documented
research known to this author.
SPCC (1979b) found that oysters taken from the Georges River, had
elevated levels of a number of potentially toxic metals. The degree of contamination varied throughout the estuary, with generally lower levels
experienced in those downstream areas subject to comparatively· high levels
of tidal flushing.
Mackay et al. (1975) sampled oysters from 19 of the oyster
growing estuaries and embayments of the N.S.W. coast. Oysters were sampled
for copper, zinc, cadmium, lead and arsenic. Results for the Camden Hav~n
estuary, as presented by Mackay et aZ., were all well below the recommended NHMRC standards. The documented methods and results ot Mackay et
aZ. also present an indication of metal uptake with respect to oyster age
and the affects of location on the accumulation of heavy metals by S.
commerciaZis. They suggest a method of sampling and analysis for the
future monitoring of metal levels in this species.
With regard to bacterial contamination of oysters, concern for
the possibility of ingestion of viral pathogens from oysters harvested
from N.S.W. waters has been expressed since the early 1960s. During this
period, under the leadership of Dr Myers, investigations were made on the
possibility of purifying oysters by the use of Ozone. While definite
recommendations were made, no regulations for purification or control of
sewage discharge to estuaries followed these recommendations. In July
1978, there was a major outbreak of gastro-enteritis attributed to Georges
River oysters. At least 1500, possibly as many as 5000 persons, were
affected (SPCC, 1979). The causative agent was identified as a parvovirus
(Norwalk virus), entering the estuary as a result of overloading of the
sewage system by heavy rain (pers. comm., Health Commission of N.S.W.).
- 55 -
Following the 1978 outbreak, the Health Commission of N.S.W.,
in cooperation with N.S.W. State Fisheries, instigated a series of dry
and wet ~eather tests of oysters throughout the estuaries of.N.S.W. This
investigation was a~med at establishing pollution levels within N.S.W
estuaries by analysis for total c9lony count, faecal coli forms and
Escherichia coli accumulated within mature·oysters. Results of the tests
led t; reg~lati?~s controlling the future preparation and marketing of
oysters. Under the Pure Food Act (1908), Regulation 19B(a) ,. by May 1983,
all oysters marketed were required to have been purified in an approved
depuration plant, no matter where they were harvested.
The Health Commission investigation also established priorities
in terms of those eight estuaries in which depuration plants were to be
in operation by a gazetted date, well prior to that applicable state-wide.
The Camden Haven estuary was one of those estuaries so defined. The
eight estuaries which, in bacterial terms, were defined as being the 'most
polluted' were Brisbane Waters, Georges, Macleay, Brunswick, Wooli, Camden
Haven, Tweed and Manning Rivers. These rivers vary in representative parameters such as catchment size and alteration, development pressure, tical
volume and freshwater flow. The one linking factor, as resultant ~rom
the Camden Haven study (Creighton, 1983) and a preliminary investigation
of Wooli and Brunswick Rivers, was the inadequate treatment of human waste,
particularly overloaded and/or poorly located septic tanks.
'Purification of oysters before marketing can be regarded as only
a stop-gap solution to the health problems associated with the inadequate
treatment of human waste and the subsequent uptake by estuarine organisms
of viral pathogens. Problems associated with this approach include the
following:Depuration depends on the oysters continuing to feed while
in the depuration tanks. It would seem that, for satisfactory removal of viral pathogens, a salinity level of 31-34
ppt and a temperature of l8-22°C are required (pers. comm.
Health Commission of N.S.W.). These conditions are not
always available to the oyster farmers at their point of intake.
Depuration'will probably have'no effect on any contaminants
present in a cellular form. Further, the survival rate of
viral pathogens has yet to be determined. No evidence is
yet available which confirms that all viral pathogens will
necessarily be removed from the gut of the oyster.
Not all oysters will be purified. For example, those oysters
harvested by the public from public oyster leases and other
non-commercial areas such as training walls.
Other species of estuarine biota are susceptible to viral
.pathogens. For' example, two cases of non-transferable
cholera have been reported as resulting from the eating of
Clarence River School prawns. Mud crabs, S. serrata, may
also accumulate viral pathogens. While no species-specific
studies are known, overseas studies have shown the accumulation of viral pathogens in similar species (e.g., Giralomo,
Wicqyashi, Miranda, Wehneger, 1972).
It is suggested that, in association with the presently enforced
pruification regulations, steps should be taken to monitor and control
discharges to the estuaries of N.S.W. The control of these discharges
can be seen, not only as a reduction in the risk to public health, whether
it be through the ingestion of oysters, Mud crabs and other species, or
through the intake of water during recreational pursuits, but also as a
means to reduce the discharge of enrichments (particularly nitrates Viraraghavan, 1982) and toxic chemicals to the estuaries. Later discussion presents a suggested method whereby oysters may be used for such a
History of Harvesting and Cultivation of Oysters
Within the Camden Haven Estuary
The natural oyster beds of the Camden Haven estuary were being
commercially exploited by the early l880s. Figure 23 details the recorded
production from 1883 to 1980. A summary of the following review of methods
of culture and reasons for production fluctuations are appended to the
figure. Documentation of the Camden Haven oyster industry prior to 1900
is contained within the Annual Reports of N.S.W. State Fisheries. The
following information has been extracted from these reports.
In February 1883, the Chief Inspector of Fisheries reported on
the presence, location and condition of five dredge beds, four of which
were situated in the entrance channel, and the fifth in Stingray Creek.
Details of these dredge beds as of February 1883, are as follows:No.1, 'the upper bed':
The bed was
60 metres in an average water depth of two to
the bed was silting up very rapidly, reducing
20 metres. Sample dredges found a reasonable
small in size.
originally 370 metres by
three metres. By early 1883
its width to approximately
quantity of oysters, though
No.2, 'the middle bed':
This bed was downstream of No.1, but
still upstream of the present Dunbogan-Laurieton bridge. Originally the
bed was 200 metres by 40 metres wide. By 1883 the bed was reduced to
half this size, with few oysters remaining on the bed.
No.3, 'the lower bed': This bed, below the present DunboganLaurieton bridge, was originally 370 metres by 30 metres, but, like No.2,
in consequence of silting was only half this size in three to four metres
of water. All of these beds (1, 2 and 3) originally had shelly to sandymud bottoms.
No: 4, 'the mi I I bed':
This bed was on a rocky, shingly bottom
situated in front of the saw mill (adjacent to the present Fishermen's
Cooperative)., The bed was 'small and relatively unimportant', containing
few oysters when inspected.
No.5, 'the creek bed':
This bed, 250 metres by 30 metres was
located in Stingray Creek, approximately midway from Camden Point to
Queens Lake entrance. This bed ~as found to be slowly silting over a
pipeclay bottom with shells and soft sandy mud. water depth was between
~wo and three metres.
inaeose I
scare ;
effort, improved 18Clwliques,
State- wide;
fremes, mudworm ;
Flood / freshes,
floods /
exhausted ;
rock I
- mangrove
cultiwtion- bollast
for previous
No dolo available
mudworm ;
- 57 -
Additional to these dredge beds, it was estimated that in
February 1883, 800 to 1000 bags of bank and mangrove adhered oysters
were still available for collection.
Similar to other rivers of N.S.W., the Camden Haven was rapidly
depleted of sizeable oysters, the dredge beds being depleted by the end
of 1883. The N.S.W. State Fisheries Annual Report for that year comments
as follows:The natural beds have been worked during the year under an expiring lease,
and also, subsequently by dredgers under royalty. They are now much
reduced and are closed.
The heavy exploitation of similar beds in the Georges and Hunter
rivers had led to the appointment of a Royal Commission in 1876, 'to
investigate the Oyster Fisheries'. The findings of this Commission,
published in 1877, included the following comments on oyster culture and
dredge beds:
There is no part of the world better, we might almost say .'>0 [.;nll, adapted
for the growth and culture of the oyster as New South Wales. The climate,
the nature of the cOast line, with its numerous inlets and creeks, and the
natural existence of the best varieties of the bivalve itself, all combine
to mark this country out as the most likely of all places for successful
ostreiculture. Unlike the coasts of England, Scotland, and Europe generally, where the coldness of the temperature in summer is sufficient to
prevent sometimes the shedding of the spat at all, and always to limit
the quantity of it, here we have invariably the spat distributed with a
profusion which under proper regulations would make our oyster supply unlimited and inexhaustible. And yet with all the advantage of a bounteous
supply we are actually informed that the natural beds are so nearly exhausted that a bag of oysters can now only with difficulty be raised in a
day, where a year or two ago it would have been easy to dredge 50 bushels
in the same time. The same process of exhaustion, with a few praiseworthy
exceptions, is going on in the leased beds, and we can see no remedy for
this crying evil except by making it more to the interest of those leasing
oyster beds to conserve, improve, and keep up the supply, than to clean
the beds out in the shortest possible time and have done with them.
The Report of the Royal Commission was accompanied by the draft
of a Bill, adopted with modification in the Oyster Fisheries Act of 1884.
This Act prohibited the dredging of oysters under the licence system.
Replacing the licence system was a lease system of lengthened tenure,
distributing the oyster-bearing areas amongst those willing to CUltivate
oysters, the Crown on its part affording to the lessees absolute control
over their leased areas, and complete protection against trespass.
In the Camden Haven, Frank Gibbins applied for and obtained a
series of leases. Foreshore improvement using ballast rock and stakes,
together with the management of the dredge beds, was initiated in 1886.
The work of improving the oyster leases during 1887 was considerably
affected by increased siltation and the presence of a bloom of red weed
(poss·ibly Cepcunium sp.), which "lay and decomposed on the oysters in such
quantities as to destroy them" (Annual Report, 1887). By 1894, extensive
works had been carried out, the Camden Haven producing 750 bags of oysters
for the year. The report of the Fishery Inspector, Fredrick W. Smithers,
details the condition of the industry and methods employed:-
- 58 -
During my last visit to Camden Haven, I examined the whole of
the areas leased to Hr. F. Gibbins, and it is with gratification that I
am enabled to report favourably on the areas in question •.. I found every
available patch of his leases on the river was covered with ballast carefully placed in order to catch spat, thereby making barren foreshores
prolific, as can be seen upon casually looking at the stones, which are
covered with spat, when, upon their attaining a few months growth, they
are carefully knocked off and placed upon other leases for maturing
purposes. Again if whole stones are removed fresh ones are put down,
everything in fact, being carried out in a most scientific and systematic
manner. Any mangrove foreshores are utilized in the same way .
•.. The sequel to this success, in the first place, - 1. By the
lessee studying conscientiously his future interests. 2. Carrying out
oyster culture as ·far as his energy and means will permit. 3. Conservation of spat supply. 4. Avoiding overworking. 5. The interest taken
in the matter by manager and men. 6. By paying the employees so much per
week to attend to the areas, instead of so much per bag to gather them,
as is done by others.
Taking the deep water beds as a whole they are very creditably
managed indeed, and might be taken as a pattern by other oyster leBsees.
The foreshores, which are used for catching spawn, present a
wonderful contrast to that which prevails on other lessees' areas.
The foreshores, also, on which the oysters are laid down, present a magnificent sight, being a mass of oysters. It is highly satisfactory to know that such were removed from beds upon which they could
not attain a large or rapid growth, and are now doing well where they
have been transplanted, and it is still much more satisfactory to see the
public estate improved in this manner .•••
.•. In conclusion, I would draw attention to the fact that seven
years ago Camden Haven was almost totally devoid of oyster life, and I
submit that my report upon its present oyster bearing qualities will be
received with pleasure by the Conmrissioners.
N.S.W. State Fisheries Annual Report, 1894
The mudworms (presumably Polydora webBteri) first appeared in
the Camden Haven estuary in 1896. By this time infestations of worms were
greatly diminished throughout the remainder of N.S.W. No explanation for
the time lag between the appearance of mudworm in the adjacent Manning and
Hastings Rivers (late l880s) and the Camden Haven can be given. Two
possible explanations are as follows:The occurrence of mudworm in the Camden Haven is related to
the transportation of ballast and shell from the Hunter
River, this occurring in the mid-1890s.
Silt loads in the Camden Haven prior to the mid-1890s were
not of significant magnitude to foster large populations of
Production in the Camden Haven estuary was affected by mudworm, particularly in the years 1896, 1898 and 1900. Due to the presence of the mud-
- 59 -
worm, the impact on production of the increase in effort of the l890s
was not apparent until 1901, production then being 2,181 bags from a
total of 23,600 metres of foreshore held by three lessees. Total N.S.W.
production for 1901 was 18,473 bags.
During 1902 an Act of Parliament was passed to further regulate
the fishing and oystering industries. The most important clause of this
Act, so far as it effected the oyster industry, was as follows:-
Every lessee shall cultivate his leased area by laying down below highwater mark sufficient quantity of clean, hard substances, such as stones,
shells, stakes, shingles, tiles, logs, or other like material for catching spat, within twelve months of the issue of the lease, and any
person failing to take proper steps to cultivate such leased area shall
be liable to have it cancelled.
Oyster and Fisheries Act, 1902
This provision had the effect of stimulating the more negligent
lessees throughout the state to improve their leases, in order to obviate
the risk of forfeiture. The Annual Report of 1903 details the cultivation
methods in the Camden Haven in accordance with those methods defined in
the Act of 1902. In part, the Report states:-
... rows of ballast stones, in some cases parallel to and others at right
angles from the shore. Oak, mangrove, and honeysuckle boughs and stakes
along the shore, shingles driven into the soil in oblique positions
parallel to the shore about half-tide mark .•• On one lease inspected I
evidenced an area of 800 yards taken up on pure sand in a good run of tide,
and ballast stone about three feet high laid along the shore about halftide mark, and scores of oysters about four months old can be seen on the
underside of each stone.
N.S.W. State Fisheries Annual Report, 1903
While cultivation area increased and methods improved, gradual
deterioration in the dredge bed productivity offset the increased effort.
Production during this period reduced to less than 800 bags per year. The
decline in dredge bed productivity can be attributed to increased siltation (already noted as a problem in 1883), together with the periodic
heavy infestations of mudworm. The colonization of silted"dredge beds by
seagrass (presumably Zostera sp.) is well documented in the Annual Report
of 1907:On one of the large beds in the main channel it was noticed that there had
been a great recent acquisition to the growth of the seagrass around and in
the vicinity of the oysters. This grass is a real danger at times, as it
sometimes spreads with great rapidity and acts as a break for sedimentary
matter, which settling upon the oysters, completely buries and smothers
Larkum (1976) takes a slightly different view on the role of seagrass with respect to sedimentation and oyster dredging. In a discussion
of the seagrasses of Botany Bay, he suggested that oyster dredging with
the inevitable ripping out of seagrass beds would increase the problems
of sedimentation. Larkum noted that once the protective covering of seagrass was removed the sediments became mobile and subject to wave action.
He suggested that the moving sand, the heavy load of silt in the water and
the increased turbidity of the water would have made the growth of both
Zostera sp. and oysters impossible. In the Camden Haven estuary, dredges
- 60 -
without catching'bags were used to clear the dredge beds of seagrass.
This may have compounded the problems of sedimentation. However, the
reported increased growth of seagrass on the dredge beds is not in concurrence with Larkum's interpretation of events subsequent to the initiation of dredging. It is suggested that increased silt loads within
the estuary (soil erosion - agricultural and forestry operations within
the catchment) resulted in changes to the substrate, allowing the colonization of Zostera on what was previously a shelly, sandy-mud substrate.
The increased CUltivation effort in itself, caused further
problems, particularly in obtaining a suitable substrate for spat collection. By 1911 Mr Gibbons was using a motor launch for the purpose of
collecting and towing mangroves for spat collection. By 1913 most of the
available mangrove on the Camden Haven had been cut and used. Similar
problems were being encountered State-wide, with larger rivers, such as
the Hastings and Clarence, supplying mangrove to the smaller estuaries.
Mangrove cutting was regulated by means of licences in the late 1900s,
with, in 1924, further conditions relating to the cutting of mangroves
imposed with the object of utilizing all parts of the tree. Dunstan (1976)
suggested that mangrove areas harbour the microorganisms essential as
food for the oysters. Destruction of the mangrove areas of the Camden
Haven may, in part, account for the continued low productivity over this
By World War I the Camden Haven oyster industry had reduced in
foreshore lease length to 17,375 metres (29,210 metres in 1908), with
seven men employed using two launches, two boats and two punts. The
reduction in lease area reflected the withdrawal of those areas previously
put under lease which were not giving the return to labour of other
leases. During the 1920s, production further reduced due to a reduction
in effort (4 men employed) and the presence of mudworm. Production in
1922 was only 128 bags, compared to a N.S.W. total of 24,811 bags. Fluctuations in production continued during the 1930s, these fluctuations
reflecting the changing climatic conditions, incidence of mudworm and
change in effort. By 1938 ten men were employed using three launches,
five boats and four punts for a production of 355 bags. Little detail is
available on the oyster industry of the Camden Haven during World War II,
the production in 1942 being 63 bags, no data available for 1943 to 1944
and no production occurring in 1945. Heavy floods and a series of freshes
in the period 1948 to 1950 further hindered production, no oysters being
marketed for the period 1949 to 1954. At this time there was a total of
28 foreshore leases comprising 14,645 metres and 6 offshore leases.
Further floods in 1956 reduced production for the period 1956 to 1958.
Increased effort, together with improved c~imatic conditions led to a
production of 920 bags in 1959.
During the early 1960s, production fluctuated from peaks of 729
bags and 749 bags in 1960 and 1963 respectively to nil p~oduction in
both 1961 and 1962. From 1967 onwards, with dry conditions and increased
interest in the industry, further leases were laid down, particularly in
Gogleys Lagoon. By 1970 there were 44 foreshore leases of 17,430 metres
total length, together with 55 hectares of offshore leases.
The 1970s saw further increase in effort in oyster production
in the Camden Haven, together with the application of improved methods to
increase productivity. This increased effort was offset by heavy flooding
- 61 -
in 1973, this flooding being followed by an infestation of mudworm, the
production 1975 falling to 276 bags from 1, 5Ql bags in 1974. Reduction in
mudworm infestation, together with dryer climatic conditions in the
latter part of the 1970s, led to increases in production commensurate
with effort and techniques employed. Production in 1976 was 1,975 bags,
in 1977 1,913 bags, in 1978 3,672 bags, and in 1979 3,227 bags. It is
interesting to note that it was not until 1978 that the production of
1901 of 2,181 bags was exceeded.
The present Camden Haven oyster industry employs some nine
owners full-time, an additional eight owners part-time, three full-time
employees and 12 to 15 casual employees. Tray production is becoming
the dominant method of cultivation. Most of the: stick production is for
provision of spat for trays. With the introduction of purification, it
is virtually necessary to tray oysters prior to purification and marketing.
Spat (overcatch) and barnacles are a major deterrent to st,ick production in
the entrance channel and Gogleys Lagoon. The majority of stick production
is therefore located in Queens Lake which usually produces spat free
oysters because of weed growth. Recent attempts at cultivation in Watso,~
Taylor Lake appear not to have been very successful. It is suggested that
this may be due to high turbidity levels, rather than low salinity levels.
(Recent experiments suggest that the range of osmoconformity for the
Sydney rock oyster is between 15 and 45 ppt salinity. Feeding rates
altered little over this range - pers. comm., J.A. Nell, N.S.W. State
Fisheries. )
Nursery areas are found between North Haven Bridge (crossing
Stingray Creek) and Camden Point. This is the only area of the waterway
where conditions are suitable for spat growth. It is essential that the
area be protected to ensure continuity of spat supply to the local oyster
Camden Haven oyster growers suggested to the author during the
course of this investigation a series of problems/issues. These are as
Depuration Versus Water Quality Control:
As discussed in detail
by Creighton (1982), the sources of viral pathogens within the Camden
Haven are limited. Adequate control of human waste disposal techniques,
particularly septic tanks, was considered to be far preferable than the
implementation of purification regulations - with the subsequent costs of
depuration plant for each grower.
Si Itation Within the Estuary:
This problem was particularly
evident for Gogleys Lagoon. The shape of the bay and its entrances form
a very effective silt trap. This problem was previously studied by the
Department of Public Works (1977).
Relocation'of Oyster Leases:
Growers suggested that a large
proportion of the currently leased area is unused because of its unsuitability for commercial production. They suggested that rationalisation
and relocation to more suitable areas should be effected. Relocation is
difficult because of the conflicting interests with commercial and recreational fishermen. The policy of Laurieton Fishermen's Cooperative is to
oppose all applications for new leases as they claim it reduces fishing
areas. Similarly, recent applications for oyster leases have been opposed
by recreational fishermen (numerous articles in local press) •
- 62 -
Further detail on siltation within the Camden Haven is presented
in Creighton (1984). Oysters and water quality are discussed at length
in the following section. The problems of lease rationalization are
beyond the scope of this project.
While yearly production principally reflects effort and the
cultivation techniques utilized, generalist information on estuary condition is also presented by the previous analysis. Aspects worthy of
mention are as follows:Dec I ine In the Dredge Bed Resource:
The decline of the dredge
bed resource can be attributed to two factors - overharvesting and sedimentation. Overharvesting has only a short-term effect on the resource.
Providing conditions remain suitable, it is expected that over time the
resource would be replenished. This has not occurred to any great extent.
This may be attributed to sedimentation within the estuarine areas that
once provided suitable substrate for larval recruitment. Oyster larvae
will not adhere to muddy/slimy sediments. A washed sandy substrate is
required. Secondly, even though these sediments still exist to some
extent on the dredge beds, the higher sediment loads within the estuary
provide a continuously suitable habitat for the mudworm.
Incidence of Mudworm:
Intertidal cultivation of oysters in the
Camden Haven has been subject to four distinct periods of heavy mudworm
infestation - late 1890s, early to mid-1920s, mid-1950s and early to mid1970s. These periods of heavy infestation coincide with major flood
events for the system. It is suggestedthat "major floods provide a large
slug of sediments to the estuary, with the recovery period following these
events extending for some years. Further supportive data for this hypothesis is contained within the Department of Public Works (1977) study
of Gogleys Lagoon. This study demonstrated that periods of major shallowing in Gogleys Lagoon corresponded to these major flood periods.
Mangroves and Oyster Production:
OVer the period 1900 to 1910,
most of the mangroves adjacent to the oyster beds of the Camden Haven
were harvested to provide a suitable substrate for spat. It is reported
that, by 1913, virtually all the available mangroves on the Camden Haven
had been harvested and that bundles of sticks were being transported from
the Clarence to the Camden Haven. Very limited information is available
on both oyster feeding requirements and the primary productivity of the
N.S.W. barrier estuaries. Because of this no specific conclusions can be
made concerning the importance of mangroves to the productivity of the
estuary in general, or to oysters in particular. It is, however, interesting to note that regardless of variation in effort, there was a marked
decline in oyster production by 1903, and that oyster production over the
period 1903 to World War II remained low. It was not until the postWorld War II period that oyster production increased significantly.
Admittedly this period also involves the adoption of improved cultivation
techniques - especially since 1970. It is suggested, however, that the
relationships between wetlands, particularly intertidal mangrove areas,
and oyster production are worthy of further investigation.
- 63 -
To provide more precise data on estuary condition via oyster
production, further data including effort, environmental 'baseline'
conditions, oyster diseases and cultivation practices is required. Such
an approach may be justified, providing a long-term basis on which to
monitor estuary condition. Modern data storage methods facilitate this
type of analysis. It is suggested that further investigation with a view
to defining data requirements for the analysis of oyster production of
particular estuaries is warranted.
The discussion in Section 4.1.2, together with Creighton (1983),
presents two aspects with regard to oysters and water quality within
estuaries. Firstly, the data provided by the Health Commission- N.S.W.
State Fisheries investigation of bacterial contamination within oysters.,
.is suitable for the location of point sources of bacterial contamination
within the oyster growing estuaries of.N.S.~. Secondly, because-of the
feeding characteristics of oysters and the spatial location of oyster
leases within most N.S.W. estuaries, oysters may be useful indicators of
estuarine water quality - providing information on both hea\~ metal and
bacterial contamination. The following discussion briefly reviews the
method utilized to exploit available data to detect point sources of
bacterial contamination within the Camden Haven estuary. Following this
review of the method detailed by Creighton (1983), suggestions are made for
the implementation of an ongoing monitoring programme of estuarine water
It has been previously suggested to the author that the contention that the real problem with bacterial contamination of oysters is
pollution of waterways and that, if a clean water policy was adopted,
oyster purification would be unnecessary is 'somewhat idealistic' (pers.
comm., Dr Ayres, N.S.W. State Fisheries). As Dr Ayres stated, it is
idealistic in the sense that 'problems already exist in some areas and
that adequate funding for remedial and future works is simply not available on call'. While this is admitted to be so, it is considered that
wherever possible, the data already available should be utilized to
identify sources of bacterial contamination and, once identified, to
ensure that remedial works are undertaken within the framework of existing
regulations. These comments are particularly applicable to those
estuaries such as the Camden Haven, Wooli, Manning and Brunswick Rivers
where urban development is limited and easily controllable.
The identification and assessment of two major sources of
bacterial pollution for the Camden Haven estuary was based upon the
application of available data from various sources. The data used and
also readily available for most other N.S.W. estuaries is displayed by
Table 3.
The application of the data included in Table 3 relies upon the
examination of the spatial variation in E. coli, concentrations throughout the estuary (various leases) for particular freshwater discharge
characteristics. Locations where discharges are suspected to occur are
defined by this analysis. On-site inspection of these locations is then
necessary to locate imbalances within shoreline estuarine biota. The
presence of these imbalances 'verifies' the location of a discharge,
excessive nutrients being mirrored by biotic performance. If the discharge is from a septic treatment system, further verific~tion can be
obtained using the normal methods of dye ,testing. 'The only other major
point source of faecal pollution of N.S.W. estuaries is likely to be
- 64 -
Bacterial contamination - available data, sources
and application
Freshwater quality
Local council
Upper catchment contamination
Freshwater flow
water Resources
Upper catchment contamination
Salinity fluctuation
in oyster growing
N.S.W. State
Desorption of E. coli
from sediments
Oyster lease location
N.S.W. State Fisheries
Point source location
Estuarine hydrodynamics
Hydraulic surveys,
Public Works Department
Definition of transport processes within
Land use and
waste treatment
Local council
Local knowledge and
intensive animal feedlots. These are, in most cases, situated well upriver. The lower estuary oyster producing areas are expected to respond
to such a source in direct relation to their access :to contaminated upriver waters. The low survival rate of E. coli within estuarine waters
will further dampen the effects of such sources.
... '-
At most, the method will define all major sources o~ba~terial
pollution within a catchment. At least, the method is pertinent to the
resolution of bacterial pollution problems within the lower estuarine
areas. More often than not, it is expected that these pollution problems
are attributable to the poor location, performance and/or overtaxing of
septic tank systems.
The Camden Haven was one of six northern N.S.W. rivers defined
by the Health Commission of N.S.W. as being heavily polluted by organisms
of faecal origin. The information required for similar investigations of
other estuaries is readily available. It is recommended that, at best,
the Macleay, Brunswick, Wooli, Tweed and Manning Rivers be investigated
for the location of point sources of bacterial pollution. If successful,
the investigation could be extended to all oyster growing estuaries of
N.S.W. A project such as this would be simple to implement, cost effective
in that it relies on available data, assist in the control of associated
pollutants such as organic and toxic chemicals, be of benefit to estuarine
biota and of benefit to the health of the general public. Based on the
findings of such an investigation, recommendations could also be made
towards the implementation of guidelines for the treatment of human waste
within the coastal region of N.S.W.
- 65 -
The concept of on-going assessment of estuarine water quality
using S. commerciaZis as an indicator presents an approach worthy of
further investigation. It is suggested, for example, that the data
provided by Mackay et aZ. (1975) on heavy metal contamination be regularly updated with concurrent research on the identification and control
of sources of heavy metal contamination.
Similarly, it is suggested that oysters could be utilized to
regularly monitor bacterial contamination within estuaries. This, as
well as providing further 'insurance' for the present practice of depuration, would allow for the control of associated enrichments and contaminants, particularly nitrates and toxic chemicals, as well as ensuring
acceptable water quality for recreational requirements. This monitoring
scheme could be further expanded to include the analysis of chemical
derivatives of pesticides and weedicides.
If a monitoring scheme, based on S. commerciaZis, was to be
implemented some particular experimental design procedures 'tlould need to
be formulated. For example, sample oysters should preferably be taken
from a series of locations (leases) throughout each estuary. Secondly,
sampling should take account of climatic variations, with sampling
occurring during both dry and wet weather periods. Associated research
should include:shoreline surveys to identify actual and potential pollution
hydrographic studies to determine the impact of major sources
of pollution on estuarine waters with, where necessary, recommendations for control of these sources; and
analysis of these data to determine both the time period of
further sampling and, if necessary, further research into
particular aspects that the samples have demonstrated as
being a problem for a particular catchment.
As a side benefit relevant to the expansion of the Sydney rock oyster
CUltivation industry, this proposed research programme'would also provide
information that would allow for the classification of N.S.W. estuaries
on the United States scheme (Heikoff, 1980). This classification scheme
has been implemented for particular waterways in Tasmania, thereby
allowing for the export of the Pacific oyster (Crassostrea gigas) to the
United States - without, incidentally, any need for depuration .
- 66 -
This report has presented a review of the N.S.W. estuarine
fishery, data on the Camden Haven estuarine fishery and data on the
Camden Haven oyster cUltivation industry. Because of the nature of the
statistical information available, only generalist conclusions could be
made on the condition of the Camden Haven estuary.
With regard to the Camden Haven estuarine fishery, it was found
that, for particular species, notably River garfish, Dusky flathead and
Sand whiting, there has been a marked reduction in total annual catch.
The total annual catch of Luderick displayed a similar reduction with
recovery in recent years to previous levels of catch. For species such as
Flattail mullet, Sand mullet and Trumpeter whiting, the time period of
information available is not sufficient to allow for any precise conclusions concerning changes to the total catch. As well as changes to the
total catch, there has been changes to the proportion of catch by species.
A distinct increase in the proportion of catch for Luderick, River garfish
and Sand mullet was noted. A decrease was apparent for Dusky flathead ,nd
Flattail mullet. As for total catch, information available is insufficient
to precisely define the nature and reasons for these apparent trends.
Inadequacies' in th~ information available were list~d' i;r' each
particular species. It can be concluded that the statistical information
presently collected does not allow for any detailed analysis of the ecological nature of the estuarine fisheries of-N.S.H. Suggestions for
revision and alteration to the data collected on estuarine fisheries,
together with suggestions for further research, were presented in Section
3.:a 'S;-(.IF'3es-4·S-51). Suggestions for alteration to data collection
include(the following aspects:- area of capture, effort and catch data,
seasonality and age of catch, information on 'regional' stocks, further
species delineation, particularly crustaceans, environmental 'baseline'
factors, and market and economic factors. Areas of further research
includel- fish movements, population assessment, further data on life
history features, and data on the influence of man-induced changes on
species and populations.
The review of available data on the oyster cultivation industry
of the Camden Haven was, as for the fishery, restricted by the lack of
appropriate data. Generalist comments were, however, possible on the
nature of sedimentation in the estuary, and the significance of mangroves
to oyster production. To provide more precise data on estuary condition
via oyster production, further data including effort, environmental 'baseline' conditions, oyster diseases and cultivation practices, is required.
Further investigation with a view to defining data requirements for the
analysis of oyster production of particular estuaries was recommended.
The use of the Sydney rock oyster (S. aommeraiaZis) as an ongoing monitor of estuarine water quality was also discussed. It was
recommended that available data on bacterial contamination be utilized in
an attempt to identify point sources of bacterial pollution within N.S.W.
estuaries. On-going monitoring for heavy metals, bacterial contamination
and chemical derivatives of pesticides and weedicides was recommended. A
method whereby such a programme could be implemented was briefly discussed.
, l
- 67 -
1975 NaturaZ and Modified PZant Communities as ReZated to
Runoff and Sediment YieZds. A.D. Hasler (ed.), Coup Zing of
Land and Water Systems. Ecological Studies, Vol. 10, Springer-
Branson, F.A.
Verlag, N.Y.
Bryant, E.
1980 Bathymetric Changes in Three Estuaries of the Central
New South WaZes Coast. Aust. J. Mar. Freshwater Res., 1980, 31,
Burdon, T.W. 1971 The DeveZopment of AustraZian Fisheries. CSIRO Div.
Fisheries and Oceanography, Essays in Fisheries Sciences. Sydney.
Cheng, D.M.H. 1981 CoastaZ Lagoons in New South WaZes.
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Chubb, C.F., I.C. Potter, C.J.
wetlands (Aust-
Grant, R.C.J. Lenanton and J. Wallace
Age Structure, Growth Rates and Movements of Sea MuZZet, MugiZ
cephaZus L., and YeZZow-edge MuZZet, AZdrichetta forsteri
(VaZenciennes), in the SWan-Avon River System, Western AustraZia.
Aust. J. Mar. Freshwater Res., 32, 605-28.
'Clark, J.
1977 CoastaZ Ecosystem Management: A TechnicaZ ManuaZ for the
Conservation of CoastaZ Zone Resources. John Wiley and Sons,
1947 Studies on the Economio BioZogy of the Sand Whiting
(SiZZago oiZiata C and V). Proc. Linn. Soc., N.S.W., 72(3-4),
Cleland, K.W.
Collett, L.C. 1976 Estuaries: Salvation Through Proteotive LegisZation?
N.S.W. State Fisheries Leaflet No.2, Our VuZnerabZe Estuaries.
N.S.W. State Fisheries, Sydney.
1982 CoastaZ Region EnvironmentaZ Assessment and Management. TechnicaZ Report 3: Water QuaZity Within the Camden
Haven. Report to the Coastal Council of N.S.W., University of
Creighton, C.L.
New England, Armidale.
1983 The Lake Innes-Lake Cathie Catchment: Resource
AppraisaZ with Recommendations for Restoration Works and Management. University of New England, Armidale.
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