Status of Balearic Shearwater, White

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Status of Balearic Shearwater, White
Status of Balearic Shearwater,
White-beaked Dolphin and
other marine animals in Lyme
Bay and surrounding waters
Tom Brereton1, Russell Wynn2, Colin MacLeod1,
Sarah Bannon1, Becky Scott1, Jo Waram1, Kate
Lewis1, James Phillips3, Clive Martin1, Roger Covey3
1
Marinelife, 2 SeaWatch SW, 3 Natural England
Marinelife
St Andrews Road, Bridport, Dorset
www.marine-life.org.uk
May 2010
`
Table of contents
Summary
1.0 Introduction
1.1 Objectives
1.2 Policy relevance to Natural England
2.0 Study area
2.1 Habitat and fisheries
2.2 Baseline offshore effort-related surveys – Kerr-McGee study and SCANS II
3.0 Focal species
3.1 Balearic Shearwater
3.1.1 Conservation status
3.1.2 Range & population
3.1.3 Life cycle
3.1.4 Diet
3.2 White-beaked Dolphin
3.2.1 Protection measures
3.2.2 Distribution
3.2.3 Behaviour and social structure
3.2.4 Abundance
3.2.5 Diet
3.2.6 Recent distribution shifts
4.0 Methods
4.1 Opportunistic surveys
4.2 Natural England surveys
4.3 Land-based counts of Balearic Shearwater
4.4 Overlaying sightings with environmental data
4.5 Stakeholder engagement
5.0 Results
5.1 Balearic Shearwater
5.1.2 Effort-related observations from sea
5.1.3 Land-based counts
5.1.3.1 Balearic Shearwaters in Lyme Bay prior to 2007
5.1.3.2 Balearic Shearwaters in Lyme Bay in 2007-08
5.2 White-beaked Dolphins in Lyme Bay
5.2.1 Sightings between 2006 and 2009
5.2.2 Co-occurrence with other cetacean species
5.2.3 Association with seabirds
5.2.4 Other recent records of White-beaked Dolphin in the Channel
5.2.5 Photo-Identification catalogue
5.3 Other seabirds recorded in Lyme Bay 2007-2009
5.4 Other cetaceans seen recorded in Lyme Bay 2007-2009
5.4.1 Effort related sightings
5.4.2 Casual sightings
5.5 Stakeholder engagement
5.5.1 Postcard distribution
5.5.2 Fishermen impacted by the ban on scallop dredging
6.0 Discussion
6.1 Importance of Lyme Bay for Balearic Shearwater
6.2 Possible reasons why Portland is important for Balearic Shearwaters
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6.3 Importance of Lyme Bay for White-beaked Dolphin
6.4 Possible reasons why Lyme Bay is utilised by White-beaked Dolphin
6.5 Recommendations for future work
6.5.1 Repeat Natural England funded transect surveys/further analytical work
6.5.2 Targeted surveys for White-beaked Dolphin and Balearic Shearwater
6.5.3 Investigating ecology of Balearic Shearwaters through satellite telemetry
6.5.4 Acoustic monitoring of White-beaked Dolphins in Lyme Bay
6.5.4 Developing a Lyme Bay Wildlife Officer post
6.5.5 Extending White-beaked Dolphin work beyond south-west England
7.0 References
8.0 Acknowledgements
9.0 Appendices
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List of Tables, Figures and Appendices
Figure 2.1: Sediments of Lyme Bay and surrounding waters (taken from Poulton et
al 2002).
Figure 2.2: The location of fronts and mixing properties of Lyme Bay and
surrounding waters (Source Maddock et al. 1981)
Figure 2.3: The Shambles Bank off Portland Bill. (Source Pingree 1978)
Figure 2.4: Distribution of main fishing activities in Lyme Bay on sightings from the
DSFC patrol vessel 2005-6 (Source: University of Plymouth)
Figure 3.1: Breeding distribution (pink circles) of Balearic Shearwater in the
Mediterranean (Source: European Bird Census Council)
Figure 3.2: White-beaked Dolphin global distribution (Source: adapted from
Cawardine, 1995).
Figure 3.3: Distribution of White-beaked Dolphin around the British Isles.
Figure 3.4: Location of White-beaked Dolphin stranded around the UK and Ireland
by region (black lines).
Figure 3.5: SCANS II abundance estimates for White-beaked Dolphin. (Source:
Hammond and MacLeod 2006).
Figure 4.1: Effort-related surveys in Lyme Bay 2007-2009 (red = NE funded surveys
in 2009, green = other)
Figure 4.2 Dolphin and shearwater postcard surveys
Figure 4.3 Data entry and reporting functionality of new web pages to capture
sightings from local skippers and members of the public
Figure 5.1: Balearic shearwaters recorded in Lyme Bay from effort-related and
casual surveys.
Figure 5.2: Temporal distribution of Balearic Shearwater records in Lyme Bay
during 2007-08
Figure 5.3: Monthly sightings of Balearic Shearwaters in 2007
Figure 5.4: Monthly sightings of Balearic Shearwaters in 2008
Figure 5.5: White-beaked dolphins recorded in Lyme Bay 2006- 2009 from effortrelated surveys and casual records.
Figure 5.6: Water temperatures in 1-km squares where White-beaked Dolphins
were recorded
Figure 5.7: Cetacean sightings in months when white-beaked dolphins were
recorded in Lyme Bay 2007-2009.
Figure 5.8: Cetacean sightings in months when white-beaked dolphins were not
recorded in Lyme Bay 2007-2009.
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Figure 5.9: Casual sightings of White-beaked Dolphin post 1985 (excluding Lyme
Bay records post-2005)
Figure 5.10: European Storm-petrels recorded in Lyme Bay from effort-related and
casual surveys. .
Figure 5.11: Great Skuas recorded in Lyme Bay from effort-related and casual
surveys during the summer months 2007-2008.
Figure 5.12: Great Skuas recorded in Lyme Bay from Natural England effort-related
and casual surveys in the early winter period 2009.
Figure 5.13: Distribution and relative abundance of Guillemots in Lyme Bay on
Natural England surveys during the early winter period in 2009.
Figure 5.14: Harbour Porpoise effort-related sightings from Marinelife surveys in
Lyme Bay during the summer (Apr-Sep) and winter (Oct-Mar) months 2007-2009.
Figure 5.15: Cetacean sightings on monthly Kerr-McGee transects in 1994. Left
side - Bottlenose Dolphin, Right side – Harbour Porpoise (Source: Leaper et al.
1995).
Figure 5.16: Casual sightings of cetaceans in Lyme Bay in 2009 obtained through
the Natural England project.
Figure 5.17: Location of ports (yellow crosses) where postcards have been
distributed to local skippers
Figure 5.18: Location of sailing clubs (yellow crosses) where postcards have been
distributed to local skippers...
Figure 6.1: Elevated Total Suspended Matter concentrations (a turbidity measure)
concentrations off Portland Bill in early July 2007. (Source: Plymouth Marine Lab)
Figure 6.2: The proportion of sightings of each species in 1oC temperature classes
for summer months from 1983-1998.
Table 4.1: Effort-related surveys in Lyme Bay and surrounding waters 2007-2009
Table 5.1: Monthly summary of Balearic Shearwater sightings
Table 5.2: Monthly summary of White-beaked Dolphin sightings
Table 5.3: Seabird sightings in Lyme Bay seen on Natural England surveys from
February to April 2009
Table 5.4: Effort related cetacean sightings in Lyme Bay 2007-2009
Appendix 9.11: Balearic shearwaters recorded in the English Channel from survey
and casual effort.
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Summary
Lyme Bay is an ecotone which supports both warm waters species of the south west and
colder water species of the North Sea and eastern Channel. Habitat and species variety is high
and the area is well known for the occurrence of a number of rare species of lower trophic
levels, including sea slugs and sea fans associated with reef habitats. Seabirds and cetaceans
are well monitored from coastal watchpoints, with important species regularly occurring
including Bottlenose Dolphin, Harbour Porpoise and Balearic Shearwater. Sightings of
Balearic Shearwater are collated annually by SeaWatch SW.
The offshore status of seabirds and cetaceans is less well known. There are surprisingly few
casual records of cetaceans (Peter Evans pers. comm.) and only two systematic scientific
surveys have been carried out, with the inner Bay sampled for seabirds and cetaceans in
1994/95 (Kerr McGee Oil) and the outer Bay for cetaceans in 2005 (SCANS 2). There is a
pressing need for offshore sightings data and interpretation of both offshore and land-based
sightings data to inform the identification of candidate Marine Protected Areas (MPAs),
Special Areas of Conservation (SACs) (e.g. for Harbour Porpoise) and Special Protection
Areas (SPAs) (e.g. for Balearic Shearwater).
In 2007, the conservation and research charity Marinelife, in collaboration with the RSPB and
SeaWatch SW, established a programme of cetacean and seabird surveys in the offshore
waters of Lyme Bay, focussed on Balearic Shearwater. The principal aim being to provide to
inform the selection of protected areas, whilst understanding the prey items and feeding
distribution of Balearic shearwaters is a requirement of the European Action Plan for the
species. The surveys detected a wide diversity of cetaceans and seabirds in Lyme Bay. Of
particular significance were regular sightings of two focal species - Balearic Shearwater and
White-beaked Dolphin. A number of White-beaked Dolphins had unique markings,
highlighting the potential to develop a photo-identification catalogue for this species. In view
of the interest found, a programme of community engagement was established to encourage
and collate casual records from local skippers and other recorders, with encouraging results
(e.g. bringing in new sightings data that were not being captured elsewhere).
In 2009, a wide-ranging project was established with Natural England to synthesise
Marinelife and SeaWatch SW information on Balearic Shearwater, White-beaked Dolphin
and other marine animals in Lyme Bay to inform future conservation strategies and to
continue to develop the programme of public and local skipper engagement. Specific project
objectives included (1) to carry out a systematic winter survey of Lyme Bay for Balearic
Shearwater and White-beaked Dolphin (2) to assess the status of these two focal species in
Lyme Bay (3) to develop and publish Marinelife’s photo-identification catalogue of Whitebeaked Dolphin and other cetaceans (4) to develop the local skipper engagement work and
assess opportunities (e.g. eco-tourism) for fishermen impacted by the ban in Lyme Bay on
scallop fishing and bottom trawling and (5) to suggest future policy relevant research and
engagement work.
In an effort to increase the number of records submitted by the public, a postcard survey was
launched for Lyme Bay dolphins and shearwaters and a website established to enable online
submission and reporting of data. The postcards were distributed to 185 skippers of angling,
diving and leisure boat trips and 44 Sailing Clubs southwest England.
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Balearic Shearwater is Europe’s rarest seabird and is classified as globally and critically
endangered by the IUCN. It is threatened by alien species, overfishing, drowning in fishing
nets and human disturbance. White-beaked Dolphin is a UK BAP Priority species (Grouped
plan for small dolphins) and is suspected to be declining in the southern parts of its range in
UK waters. It is threatened by climate change and over-fishing.
In this report we analyse the status of Lyme Bay of Balearic Shearwater and White-beaked
Dolphin from ~4800km of effort-related offshore surveys (n=~50), and from casual records
including ~500 land-based Balearic Shearwater records collated over 2007/8 by SeaWatch
SW.
Analysis of land-based records collated by SeaWatch SW indicate that in recent years
internationally important numbers of Balearic Shearwaters have visited Lyme Bay, with the
area regularly holding a third of the annual UK and Irish sightings total. Three-figure counts
of Balearic Shearwaters have regularly been made in recent years, indicating that up to 0.5%
of the World population may be present in Lyme Bay at any one time. There are also
indications that numbers utilising Lyme Bay, and southwest UK in general, are increasing,
probably in response to climate and fisheries-driven changes in prey availability. The number
of birds utilising Lyme Bay show marked inter-annual variability (e.g. 50% fewer in 2008
than 2007), probably in response to local changes in prey distribution. Birds principally occur
between June and October, although winter sightings are increasing.
A key issue is how Balearic Shearwaters utilise Lyme Bay and whether the majority are (1)
seasonally resident birds utilising the Bay to feed and moult or (2) wind-driven birds
temporarily displaced from core areas further south or (3) wind assisted birds, undertaking
large-scale foraging movements in favourable weather conditions. Available land-based and
at-sea sightings data indicate that the waters within a few miles of Portland Bill are regularly
used by important numbers of moulting/foraging birds in some (but not all) years. In 2007, a
minimum of 0.5% of the global population was thought to be foraging off the Bill area over
the late June/early July period with smaller numbers through the summer. Portland Bill may
be an important foraging area for Balearic Shearwater because (1) local conditions can (in
some years) support the development of concentrations of key prey items including Anchovy,
other shoaling fish and plankton(2) the area (especially the Shambles Bank and Portland Race
) is relatively heavily fished and provides enhanced opportunities for scavenging. Away from
Portland Bill, no significant at-sea concentrations have yet been found and in the central parts
of Lyme Bay birds have only been found in extremely low densities (widely dispersed in ones
and twos), usually scavenging around angling and fishing boats. As has been demonstrated in
the Mediterranean, scavenging is similarly thought to be a key foraging strategy in Lyme Bay.
There may be hotspots that have yet to be discovered, especially in under-sampled inshore
areas of the western Bay between Beer and Prawle. However, the paucity of offshore records
and the correlation between high counts from land and periods of fresh winds from the
south/west, suggests that that the bulk of birds seen on a number of the high count days are
likely wind-driven (or wind assisted) birds from further south (e.g. coast of north west France)
that exit Lyme Bay equally rapidly. Thus high day counts from land can give a false
impression of how many birds are regularly utilising Lyme Bay to moult and feed over the
summer months. (Stop press this was confirmed later in 2009, when 1000 birds
were recorded summering in the Bay de St Brieuc on the north Brittany coast
west of St Malo).
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From July 2006 to April 2009 twenty sightings of ~300 individual White-beaked Dolphins
were recorded in a relatively restricted part of Lyme Bay, with nine of the sightings on effortrelated surveys. Sightings have been made in all months except December (no survey effort)
and February (thought to be absent in 2009). On effort-related surveys, White-beaked
Dolphins were the second most frequently seen cetacean species after Harbour Porpoise,
accounting for approximately a fifth of all sightings. With additional sightings made in 2005
and (stop press) again in 2009, Lyme Bay can now be identified as the most southerly
known site in Europe where the species regularly occurs. Up to 200 animals have been seen,
which represents ~1% of the total population estimated for north-west European shelf waters,
confirming regional and possibly national importance. Lyme Bay may be the most important
locality in the English Channel for White-beaked Dolphin, though this cannot be confirmed
due to under-sampling of other areas. The species is extremely rare in other well-recorded
areas of the Channel (e.g. off the Normandy coastline).
The core area of White-beaked Dolphin occurrence is central Lyme Bay which has a number
of features that are thought to be important in determining presence and concur with results
from the few studies completed on this dolphin species in other parts of the UK. These
include (1) Water depths of >50m (2) Stratification of the water column in the summer (3) A
gently sloping, predominantly sandy seabed (4) Plentiful stocks of Cod and Whiting (key
known prey items), especially in the summer (5) An absence of Common Dolphin in the
summer months (6) A general absence of Bottlenose Dolphin and (7) Sea surface
temperatures below 18°C.
The long-term conservation of White-beaked Dolphin in Lyme Bay is a cause of conservation
concern due to predicted rises in sea surface temperature (SST). White-beaked Dolphin rarely
occurs in waters >18ºC and currently waters temperatures regularly reach 17-18 ºC in Lyme
Bay in the summer months.
A catalogue of uniquely marked White-beaked Dolphins (n=6) and Bottlenose Dolphins
(n=24) photographed in Lyme Bay and surrounding waters was established under the project.
The catalogue can be downloaded from http://www.marine-life.org.uk/coastallatest.html
Over the ~50 effort-related surveys between 2007 and 2009 there were 4250 seabird sightings
totalling 43,200 birds of 33 species. 15,530 birds of 30 species were recorded on the nine
Natural England surveys from February to April 2009. Seabird highlights from the surveys
included: (1) Large numbers of Guillemots and Razorbills widely distributed across Lyme
Bay in February 2009. Crude abundance estimates of 16,000 Guillemots and 4,000 Razorbills
were similar to those made in the 1994/5 baseline study, and would likely qualify the Bay as
nationally important for both species (2) The regular occurrence of moderate numbers of
foraging European Storm-petrels in offshore waters during the summer/early autumn months,
in higher numbers than the 1994/5 baseline (3) The regular occurrence of moderate numbers
of scavenging Great Skuas in offshore waters during the summer/early autumn months, in
higher numbers than 1994/5. (4) The winter presence of small numbers of Great Skua in
offshore areas, representing a westerly range extension to that previously documented.
Thirty-eight sightings of three other cetacean species were recorded on effort-related surveys
including 19 sightings of Harbour Porpoise, plus single sightings of Bottlenose Dolphin and
Common Dolphin on Natural England surveys. Amongst the sightings, of particular
significance was (1) the regular presence of Harbour Porpoise in all seasons in offshore
waters and (2) a large pod of Bottlenose Dolphins in the middle of Lyme Bay during February
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2009 comprising a high proportion of mother/calf pairs, suggesting the areas is used as a
nursery ground. The inshore sightings of Bottlenose Dolphin and offshore sightings of
Harbour Porpoise concur with the results found during the 1994/5 baseline study. Fifty casual
sightings of six cetacean species were collated, chiefly from skippers of local dive, angling
and fishing boats following postcard distribution and personal contact. Thirty-seven of the
casual sightings were obtained during a three month period through the Natural England
highlighting the potential to encourage data flow and interest amongst local skippers with
modest resource investments. Very few of these sightings were being captured elsewhere
demonstrating that the work complements rather than duplicates existing sightings schemes.
Conclusions from the round of discussions with fishermen, representatives from fisheries
organisations and recreational dive boat owners, included: (1) It is considered that there is
currently very limited potential for fishermen involved in scallop dredging to diversify into
ecotourism and take the public out on marine wildlife trips due to high running costs. (2) A
need for less technical language when engaging the fishing community with conservation
plans and issues was identified (3) There is considerable potential to develop the skills and
interests in marine wildlife of local skippers through further engagement activities.
Although sound progress has been made in developing an evidence base on the offshore status
of Balearic Shearwater and White-beaked Dolphin in Lyme Bay, a number of the conclusions
are tentative because sightings rates and photographic captures are low and survey coverage
has been uneven. A number of recommendations are made on how the work could be
developed including : (1) Repeat Natural England funded transect surveys to enable
modelling of habitat preferences/predicted distribution and estimation of absolute abundance
from photographic captures (2) Targeted surveys to improve sample sizes of photographic
captures of White-beaked Dolphin and to identify core foraging, roosting and moulting areas
for Balearic Shearwater (Portland Bill area) and White-beaked Dolphin (3) Investigation of
Balearic Shearwater behaviour and ecology through satellite telemetry (4) Acoustic
monitoring (deployment of static hydrophones) of White-beaked Dolphins and other
cetaceans in central Lyme Bay (5) Developing a Lyme Bay Wildlife Officer post to continue
the stakeholder engagement work (6) Extending White-beaked Dolphin work beyond southwest England.
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1.0 Introduction
There are numerous localities along the shallow coastline of Lyme Bay where land-based
seawatching for seabirds and cetaceans is regularly undertaken. Recording at selected
hotspots such as Berry Head and Portland Bill has detected the regular seasonal presence of
conservation priority species including Balearic Shearwater, Bottlenose Dolphin and Harbour
Porpoise.
In contrast, little offshore scientific recording has been carried out. The only systematic
surveys were completed in 1994/1995, when Ambios Consultants intensively sampled inner
Lyme Bay for seabirds and cetaceans as part of an environmental study commissioned by
Kerr McGee Oil (UK) and in 2005, when a single trackline was sampled as part of the
SCANS 2 (Small Cetacean Abundance in the North Sea) survey. Information on the current
status of seabirds and cetaceans in the offshore waters (defined as more than 2km from land)
of Lyme Bay is generally poorly known and the middle of the Bay has never been intensively
sampled in a systematic way.
In 2006, the conservation and research charity Marinelife, in collaboration with the RSPB and
SeaWatch SW, established a programme of cetacean and seabird surveys in the offshore
waters of Lyme Bay, focussed on Balearic Shearwater. The impetus for the surveys was the
suggestion that Lyme Bay may be an internationally important moulting ground for this
highly threatened seabird (Helen Booker, RSPB pers. comm.).
The main purpose of the
surveys was to identify offshore status, behaviour (including fishery interactions) and habitat
preferences, with a view to identifying core areas of distribution that may inform selection of
candidate Marine Special Protection Areas (SPAs) for the species.
Surveys were undertaken by recruiting volunteers to carry out effort-related recording from
dive, angling and fishing boats, where passage was sponsored by the skippers. To fill
coverage gaps and seek for sought after species, a smaller number of charter trips were also
made. In addition to Balearic Shearwaters, the surveys detected a wide diversity of cetaceans
and seabirds in Lyme Bay. Of particular significance were regular sightings of White-beaked
Dolphin in a relatively restricted area. A number of the animals were photographed and had
unique markings, highlighting the potential to develop a photo-identification catalogue. Most
of the survey effort and collation of casual records was carried out during the summer months,
with the winter status of both species remaining particularly poorly known.
A programme of community engagement was established to encourage and collate casual
records from local skippers and recorders. The work demonstrated that there was
considerable interest in marine wildlife amongst many of the skippers, with high potential to
develop skills and knowledge further. In contrast relations between a number of conservation
bodies including Natural England and sectors of the shell (scallop) fishing community have
recently been strained, due to a ban on scallop dredging and bottom trawling across 60 square
miles of Lyme Bay imposed in 2008. There is a need to explore ways of improving relations
with the fishing community and to identify opportunities (e.g. ecotourism) for fishermen
impacted by the ban.
In 2009, a new project was formulated in partnership with Natural England to address some of
the knowledge gaps and to synthesise information on Balearic Shearwater, White-beaked
Dolphin and other marine animals to inform future conservation strategies and to continue to
develop the programme of public and local skipper engagement.
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1.1 Objectives
The specific objectives of the project were:
1. To carry out a systematic winter survey of central Lyme Bay covering the core area
where White-beaked Dolphins were recorded from 2006-2009 using distance
sampling techniques.
2. To describe the status and evaluate the importance of Lyme Bay for Balearic
Shearwater and White-beaked Dolphin.
3. To develop and make available via the internet Marinelife’s photo-identification
catalogue of White-beaked Dolphins and other cetaceans taken in Lyme Bay.
4. To maintain and develop public and local skipper engagement in Lyme Bay marine
animals through a sightings scheme, postcard survey, press release and other public
relations activities and to explore opportunities for fishermen impacted by the fishing
ban.
5. To suggest future research and engagement work that will support the conservation of
marine animals in Lyme Bay.
1.2 Policy relevance to Natural England
The work aims to contribute data, knowledge and stakeholder engagement activities relevant
to a number of Natural England Corporate Plan Targets including:
1.3.1: A draft plan for all English Marine Protected Areas (MPAs) by 2011, incorporating
Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) to provide a
coherent network of sites with clear agreed objectives and a monitoring strategy and a
programme in place to provide evidence-based advice to competent authorities.
1.3.2: Contribution to halting the decline in marine biodiversity by 2010, through leadership
of the marine BAP work stream of the England Biodiversity Strategy.
4.3.2: To provide data for a robust evidence base to underpin a compelling vision of future
landscapes adapting to climate change and contributing to climate change mitigation.
A1.2: The development of strong relationships with stakeholders, for the benefit of the natural
environment. Advocacy (improved liaison with impacted fishermen).
2.0 Study area
2.1 Habitat and fisheries
Lyme Bay is the largest bay in Britain covering approximately 2460 km2 and is located off the
east Devon and west Dorset coastlines of south west of England. It spans from Start Point
(3°38'21W, 50°13'16N) in the west to Portland Bill (2°27'12W, 50°30'49N) in the east, a
distance of 90 kilometres.
Within the Bay, water depths increase gradually offshore, to a maximum depth of around 60
metres at the 12 mile limit. However, around Start Point the seabed drops away steeply, and
60 metre depths are present within 5 km of the coastline. Current speeds in Lyme Bay are
generally low, around 0.5 knots inshore, increasing around headlands such as Start Point and
Portland Bill to up to 5 knots at spring tides. Sea surface temperatures in winter range
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between 6º C and 10º C, whilst in summer they are on average between 15 and 17ºC. During
the summer months, temperatures increase northwards towards the coast as water depth
decreases.
Species and seabed habitat diversity is high, because Lyme Bay is an ecotone which straddles
the divide between the warm waters of the south west, and the colder waters of the North Sea
and eastern Channel. A number of warm water species reach their easterly limit here whilst
Lyme Bay is also important area for offshore bedrock reefs which support unusually large and
mature populations of a number of slow growing and fragile species, including pink sea fan
Eunicella verrucosa, rare red seaweeds and the southern sunset coral Leptopsammia pruvoti.
A wide variety of sediments are present (Figure 2.1). Sediments are finest to the west of the
Bay with muddy sands between Tor Bay and Exmouth as well as sandy, gravel and cobble
substrata.
Figure 2.1: Sediments of Lyme Bay and surrounding waters (taken from Poulton et al 2002).
A front divides the shallows of Lyme Bay from deeper offshore water, approximately
following the 40-metre contour (Figure 2.2). On the landward side of these fronts there is
mixed water due to shallow seas and stronger tides, whilst on the deeper and slower flowing
‘open sea’ side there is stratified water (water temperature cooler in lower layers than the
surface). Within frontal zones, primary production is higher than surrounding waters,
consequently both the abundance and availability of seabird and cetacean prey is likely to be
enhanced.
Figure 2.2: The location of fronts and mixing properties of Lyme Bay and surrounding waters (Source Maddock et
al. 1981)
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To the east of Portland Bill, there is substantial tidal bank known as the Shambles Bank,
formed due to the anti-clockwise circulation of tidal water (an eddy) deflected off the Isle of
Portland (Figure 2.3). A smaller bank is also present west of the Bill. The Shambles is an
important feeding ground for seabirds.
Figure 2.3: The Shambles Bank off Portland Bill. (Source Pingree 1978)
Lyme Bay supports a wide range of fishing activity, including beam trawling for demersal
fish; (e.g. Sole, Plaice, Turbot, Brill), otter trawling for demersal fish and pelagic fish (e.g.
white fish and non-quota species including Cuttlefish, Squid, Red Mullet and Sea Bream);
winter pelagic and pair trawling for sprats; Scallop dredging; and potting for Brown and
Spider Crabs, Whelks and Lobsters. In coastal and estuary waters a number of small-scale
fisheries use a variety of methods including potting, netting (e.g. for Cod, Pollock, Ling,
Bass), lining (e.g. for Bass) and seining (e.g. for Salmon, Sea Trout, Bass and Sandeels).
Commercial fishing up to the 12 nautical mile limit is managed jointly by the Devon Sea
Fisheries Committee for Devon and the Southern Sea Fisheries Committee for Dorset. The
most important Lyme Bay fishing ports are Brixham, Teignmouth, Exmouth, Lyme Regis,
West Bay and Weymouth, although the Bay is also regularly fished by trawlers from French
Channel ports and further afield (e.g. from the Netherlands and Scotland).
Figure 2.4: Distribution of main fishing activities in Lyme Bay on sightings from the DSFC patrol vessel 2005-6
(Source: University of Plymouth)
There is a growing industry of charter (and casual) angling vessels and Weymouth is home to
the largest charter angling fleet in the country. Catch data are not recorded for anglers and
12
hobby fishermen, but it is likely that they contribute a considerable proportion of some
species landings (e.g. Cod, Conger Eel and Black Bream).
Both commercial fishing and recreational sea angling boats present many opportunities for
scavenging seabirds.
2.2 Baseline offshore effort-related surveys – Kerr-McGee
study and SCANS II
A baseline assessment of offshore seabird and cetacean status of inner Lyme Bay is available
through monthly seabird and cetacean surveys completed from January 1994 to February
1995 by Ambios Consultants for Kerr McGee Oil. Seabirds were surveyed using standardised
JNCC Seabirds At Sea Team methods, whilst cetaceans were surveyed using a strip transect
method. Three tracklines were established each comprising 6-9 sections at distances of 229km from the shore and of 10-20km in length (Figure 5.14). The total transect length was
330km, with a sample area of 1500km2. Over the 13 month period 4537km were travelled
along the tracklines.
In the Small Cetacean Abundance in the European Atlantic and North Sea (SCANS) survey in
1994 Lyme Bay was not sampled. In the 2005 SCANS II survey, a single aerial trackline ran
east from the west coast of Lyme Bay (between Strete and Slapton) through the middle of
Lyme Bay for 90km, ending 18km SSE of Portland Bill.
3.0 Focal species
3.1 Balearic Shearwater
3.1.1 Conservation status
The Balearic Shearwater Puffinus mauretanicus is the only European seabird to be listed as
critically endangered (the highest threat category) on the recently released 2007 International
Union for Conservation of Nature and Natural Resources (IUCN) Red List. It is threatened
with extinction this century due to low adult survival rates thought to be caused by a
combination of predation by introduced mammals, human disturbance and bycatch in longline
fisheries. In the Mediterranean there are extensive conservation measures underway to reduce
bycatch, eradicate predation and disturbance and to designate protected areas.
Understanding the prey items and feeding distribution of Balearic shearwaters is a
requirement of the European Action Plan for the species.
The Balearic Shearwater is the rarest bird species regularly occurring in the UK. In May
2009, it was added to the Red List of UK Birds of Conservation Concern. JNCC are currently
investigating candidate Special Protection Areas (SPA’s) for the species.
3.1.2 Range and population
The Balearic Shearwater breeds in the Balearic Islands of Spain in the western Mediterranean.
In 2005, there was an estimated 2,000-2,400 breeding pairs at 24 different sites. The world
population was thought until recently to number 8,000-10,000 individuals, however recent
13
surveys suggest the total population may number 20,000-30,000 birds. Reasons for the
discrepancy between breeding and non-breeding population estimates are unclear, but it is
most likely that this species has a particularly large floating population of immatures and nonbreeders. The presence of unknown breeding sites is a further possibility.
Figure 3.1: Breeding distribution (pink circles) of Balearic Shearwater in the Mediterranean (Source: European
Bird Census Council)
3.1.3 Life cycle
The Balearic Shearwater breeds on cliffs and small islets between February and June. Most
birds leave the Mediterranean for a post-breeding moult in the Bay of Biscay, although some
remain in the Alboran Sea and increasingly birds are summering off south-west Britain.
RSPB calculations in 2001 determined that the average UK population was 1543 birds per
year between 1995 and 1999. The increase in UK waters is most likely linked to climate
change and increases in sea surface temperature (Wynn et al. 2007) although other factors
including fisheries-related changes in prey distribution and abundance may also be important
(Votier et al., 2008).
Birds gradually return to the Mediterranean between September and November. In winter,
the species chiefly occurs in the Balearic Sea and off the north-east coast of Spain, though
increasingly birds are remaining on their northern moulting grounds.
3.1.4 Diet
Balearic Shearwaters self-forage on small shoaling pelagic fish including Anchovies,
Sandeels, Sprats and Sardines. Scavenging on fishery discards from purse seines and
demersal trawlers is also important during the breeding season (up to ~40% of foraging
efforts), when surface productivity is naturally low in the Mediterranean (Arcos et al. 2002).
Balearic Shearwaters also obtain food by capturing fish under floating drifting objects,
associating with sub-surface predators, and feeding upon plankton especially during the
morning and early evenings. Birds may form concentrations around oceanic fronts where
plankton and shoaling fishing are abundant.
14
Moulting adult Balearic Shearwater, Dorset (Photo: Tom Brereton)
Juvenile Balearic Shearwater, Dorset (Photo: Tom Brereton)
Post-breeding distribution is thought to be associated with the distribution of clupeid fish,
especially Anchovies. Therefore, the change in distribution of Shearwaters is thought to be
associated with changes in prey distribution, either linked to fishing activity or climate change
(Yesou, 2003).
15
3.2 White-beaked Dolphin
3.2.1 Protection measures
There is a wealth of European legislation aimed at conserving the species that includes:
• Appendix II of the BONN Convention, an agreement which requires protection of
migratory wild animals across all or part of their natural range through
international co-operation (applied to this species from 1983).
• Appendix II of the BERN Convention on the Conservation of European Wildlife
and Natural Habitats (applied to this species from 1987), which requires
appropriate and necessary legislative and administrative measures to ensure
protection. Any exploitation must also be regulated to keep the populations out of
danger.
• Annex IV of the EU Habitats Directive (1992) for animal and plant species of
community interest in need of strict protection. Under Annex IV the keeping, sale
or exchange of such species is banned, as well as deliberate capture and killing.
There is a requirement to assess the Favourable Conservation Status at a UK scale
of each species every six years.
• Appendix II of CITES (Convention on International Trade in Endangered
Species) - Imposes strict regulation on the trade of species that may not necessarily
be currently threatened with extinction to prevent overexploitation.
UK legislation includes:
• Schedule 5 of the Wildlife and Countryside Act 1981 (as amended), which gives
full protection within British territorial waters. The Act affords protection from
killing or injury, sale, destruction of a particular habitat (which they use for
protection of shelter) and disturbance.
• White-beaked Dolphin is also a priority species in the UK Biodiversity Action
Plan (UK BAP), being one of six small dolphin species in a grouped plan.
Relevant actions in the UK BAP that highlight the need for research, survey and
monitoring data on White-beaked and other dolphins include:
• Ensure that Special Areas for Conservation (SAC) management schemes
recognise the need for appropriate measures to protect against habitat
modification, disturbance, and contaminant inputs which might affect
dolphins. The safeguarding of these sites will require monitoring of potential
impacts, and regulation of activities.
• Give consideration to the feasibility of marine protected areas for dolphins in
the context of the proposed DETR working group on marine protected areas.
These should include consideration of the importance of the area for calving,
as a nursery ground and for feeding.
• By 2004 establish marine protected areas for small dolphins which take into
account the likelihood of human activities that would be harmful to cetaceans
living there.
• Commission autecological studies of all UK dolphin species to identify
appropriate habitat management needs.
• Support research into predicting the effects of climate change on small
dolphins.
16
White-beaked Dolphin, Lyme Bay (Photo: Gareth Knass)
3.2.2 Distribution
White-beaked Dolphin has a more limited range than most other cetacean species present in
UK waters, being found only in cool temperate and subarctic waters of the north Atlantic
(Reid et al. 2003) (Figure 3.2). The population in the eastern Atlantic is thought to be larger
than that in the west, with a range extending from northern Norway and Iceland to the British
Isles and North Sea.
Figure 3.2: White-beaked Dolphin global distribution (Source: adapted from Cawardine, 1995).
17
The species is found mostly in continental shelf waters of the northern and central North Sea
and west of Britain and Ireland, where water depth is chiefly between 50 m and 100m, and
more rarely out to the 200 m depth contour (Northridge et al. 1995; Weir et al. 2001; Reid et
al.2003) (Figure 3.3).
Figure 3.3: Distribution of White-beaked Dolphin around the British Isles. Status: Regular (dark shading);
Occasional (intermediate shading); Casual/Absent (light shading). (Source: Seawatch Foundation).
Casual and effort-related sightings data suggests White-beaked Dolphin is a rare species in
the Channel in coastal areas. For example, through almost 3000 hours of effort-based
observations off Gwennap Head over the July-October period 2007-2009, and where water
depths exceed 50m relatively close to the shore, no White-beaked Dolphins have been
recorded whilst Common Dolphin, Bottlenose Dolphin and Risso’s Dolphin are al regularly
seen. However, , there are a relatively high number of strandings from the south-west at
levels comparable with the east coast of England where the species occurs regularly offshore
(Figure 3.4). These data possibly indicate White-beaked Dolphin is under-recorded in south
west waters due to its preference for under sampled offshore waters.
Deep water (>200m) may form a geographical barrier to movement and it has been suggested
that the population around Britain and Ireland (south of north of 61oN) is discrete from other
populations in the north Atlantic (Northridge et al. 1995).
A recent study of the Minch, found White-beaked Dolphin in a restricted area in waters107122m deep and in temperatures from 13.2-13.5ºC and 22-32km from the shore (Weir 2007).
White-beaked Dolphin is much less common in the southern North Sea, the English Channel
(e.g. <20 records for the eastern English Channel) and Irish Sea, though recent year-round
ferry surveys between Essex and Holland have detected regular occurrence from March to
June (F. Zanderink pers. comm.). There have also been a few sightings in the Bay of Biscay
and as far south as the Straits of Gibraltar (Pollock et al. 1997, 2000, Marinelife unpublished
data). The few available reports of White-beaked Dolphins stranded on the French side of
the English Channel have all been of animals found during the winter months (Collet et al.
1981; Duguy, 1984; 1987; 1988).
18
Figure 3.4: Location of White-beaked Dolphin stranded around the UK and Ireland by region (black lines).
Figures in brackets represent monthly average sea surface temperatures during winter (January) and summer
(august) for the year 2000. (Source: Canning 2007).
Distribution has been linked to sea surface temperature, local primary productivity, prey
abundance and absences of other dolphin species including Common Dolphin (MacLeod et
al. 2007; Weir et al. 2007). The most important explanatory variable defining their preferred
habitat is water temperature, with their occurrence decreasing substantially in water
temperatures greater than 12-14oC (MacLeod et al. 2007, 2008). As a result, while Whitebeaked Dolphins are the most dominant neritic (shelf water) dolphin species in UK cooler
waters, they become much rarer in water temperatures above ~12-14oC and are replaced by
the Common Dolphin as the dominant neritic dolphin species when this species is present
(MacLeod et al. 2007a; 2008). At temperatures above ~18oC, White-beaked Dolphins seem
to be very rare or absent altogether. Due to a close association between water temperature
and the distribution of White-beaked Dolphins, the greatest threat to this species in UK waters
is considered to be climate change.
3.2.3 Behaviour and social structure
The social structure of White-beaked Dolphin has been little studied, although there appears
to be segregation by age and sex, with separate juvenile groups and adult/calf groups forming
(Reeves et al. 1999). The age of sexual maturity for the White-beaked Dolphin is not known
but females seem to become mature when they grow to 2.4m and males to 2.5m (~80% of
their maximum size). Not much is known about reproduction either, but mating is thought to
take place predominantly in the summer between June and September, with gestation lasting
10-11 months, with calving occurring in early summer (Kinze et al., 1997).
Although group sizes of up to 1,500 have been reported (especially in the core parts of their
range), most reports consist of 10 animals or less (Reid et al., 2003).
White-beaked Dolphins are relatively fast powerful swimmers, with average speeds of 612kmh and a maximum of up to 30kmh (Reid et al. 2003). They frequently bow-ride vessels
19
and are sometimes acrobatic (especially when feeding), breaching on to their sides or
backwards. They mix with other cetacean species to feed in some regions (Reeves et al.
1999).
3.2.4 Abundance
In the SCANS II survey in 2005, abundance was estimated at 10,565 (CV = 0.29) in the North
Sea and adjacent waters and 11,700 (CV >0.6) in the west of Scotland (Hammond and
Macleod 2006). The highest densities were reported to be in the waters off western Scotland.
The British Isles population is considered important and thought to comprise a substantial but
unknown proportion of the species worldwide total population. The previous SCANS survey
estimated abundance in the North Sea and adjacent waters at 7,856 (CV = 0.30), though the
apparent increase since 1994 (by ~3000) is not statistically significant. There is a degree of
uncertainty on the population trend as both estimates have large confidence intervals, and
there are also concerns with current abundance estimates especially for western Scotland
(MacLeod et al. in prep). None were seen in the Channel on either SCANS survey.
Figure 3.5: SCANS II abundance estimates for White-beaked Dolphin. (Source: Hammond and MacLeod 2006).
3.2.5 Diet
White-beaked dolphins eat a variety of prey including fish, squid and some crustaceans. The
diet of those found around Britain includes Whiting, Hake, Herring, Cod, Mackerel, Scad,
Sand Eel, Long Rough Dab, Trisopterus sp, and the squid Eledone cirrhosa (Evans 1992;
Santos et al. 1994 Canning 2007, Canning et al. 2008). In Scotland, the main species found in
the stomachs of stranded animals include Haddock, Whiting, Cod and other white fish
(gadoids) (Canning 2007). Most of the Haddock eaten ranged between 265-285mm total
lengths, while whiting ranged between 155-165mm total length (Canning 2007, Canning et al.
2008). In Holland, Whiting appears to be the most common species of fish eaten (Smeenk &
Gaemers, 1987; Kinze et a., 1997) while in Germany it is Cod (Lick et al. 1995).
The stomach contents of one animal stranded along the Normandy coastline has been
examined (Pierrepont 2005) and comprised of two thirds white fish ( Pout Whiting, Pollock,
Herring) and one third crustaceans.
At sea, anecdotal observations have lead to suggestions that White-beaked Dolphins have
been associated with Herring (Evans 1980) and Mackerel shoals (Evans 1987) on the west
20
coast of Scotland and that on the east coast inshore sightings coincide with Mackerel
appearing in coastal waters.
3.2.6 Recent distribution shifts
The most recent assessment of species conservation status completed as part of Habitats
Directive reporting (JNCC 2007) suggest there is no evidence of decline in range during
recent years, or historically. The assessment was largely based on SCANS and SCANS II
data. However, a substantial body of evidence suggests distribution change is occurring. A
recent study reported an apparent decline in the occurrence and relative abundance of Whitebeaked Dolphins in north-west Scotland and a corresponding increase in Common Dolphins
correlating with increases in local water temperature (Macleod 2004, MacLeod et al. 2005;
MacLeod et al. 2007). A more wide-ranging analysis indicated that there had been a marked
decline in the occurrence of White-Beaked Dolphins in 10 of the 21 coarse-scale
oceanographic regions of the UK between the 1990s and the 2000s (Macleod et al. in prep).
Since the 1990s there has also been a northerly shift in the locations of reported strandings
(Jepson 2006) from along the east coast from Norfolk upwards pre-2000, to the Highland
region of north east Scotland or the Northern Isles since 2000 (Jepson 2006). A decline has
been noted from ferry surveys in the North Sea (Frank Zanderink pers. comm.).
These distribution changes are a cause of conservation concern, as it is thought there is very
limited potential for this and other cold-water shelf species to track north as sea temperatures
rise through climate change, because beyond 60-62ºN the water is too deep (>200m)
(MacLeod et al. 2007). This change would elevate the conservation importance of any
regular occurrence of White-beaked Dolphins in Lyme Bay.
4.0 Methods
4.1 Opportunistic surveys from 2007-2009
Surveys were undertaken by volunteers on commercial dive, angling and fishing trips, with
free places provided by local skippers. Volunteer recorders from Devon and Dorset were
recruited from Marinelife, the Dorset Bird Club and the RSPB, with additional surveyors
coming forward following sightings reports published on various websites, allowing survey
coverage to extend into Hampshire and Cornwall. All of the survey effort was co-ordinated
by Marinelife. RSPB involvement ceased after 2008.
The surveys worked by teaming up volunteer recorders with individual boat skippers, so that
arrangements could be made between both parties when places became available and weather
conditions were suitable for surveys.
Trips lasted 6-12 hours, with fishing/diving being carried out at 1-3 localities over the day
anchoring for between 30 minutes and 3 hours at a time. The boats travelled at speeds of 8-15
knots. Return routes were occasionally the same as outward routes, especially when trips had
been made to wrecks well offshore.
To fill coverage gaps and seek sought after species, a smaller number of charter trips were
made, utilising the same recording methods but with up to 12 observers present.
On each trip, effort-related seabird and cetacean recording was carried out. Sightings data
collected for each Balearic Shearwater and cetacean encounter included: age and number of
21
individuals, distance (estimated using a Heinemann stick or with laser range finder
binoculars) and angle (using graticule binoculars or by angle board) to the sighting, position
(using a GPS), and behaviour and weather/sea conditions (including sea state).
For Balearic Shearwaters, behaviour at point of first observation was noted and categorised as
either: (1) Flying – passing through (2) Flying – responsive movement towards the boat (3)
Natural feeding - including seen in flight circling an area (4) Scavenge feeding around fishing
boats (including flying around the boat) and/or (5) Resting on the water. Subsequent
behaviour (if different) for the duration of the sighting was also recorded, into one or more of
the following categories: (6) Flying – passing through (7) Flying – responsive movement
towards the boat (8) Natural feeding - including seen in flight circling an area (9) Scavenge
feeding around fishing boats (including flying around the boat) and/or (10) Resting on the
water.
For cetaceans, behaviour categories (following Evans, 1995) were (1) Whale blow (2)
Slow/normal swim: leisurely surfacing with no splash (3) Feeding: prey seen in vicinity or
animal changing direction as if in pursuit (4) Fast swim: rapid surfacing, possibly with white
water (5) Leap/splashing: leaping out of the water, tail or fin slapping; (6) Bow-ride: coming
to boat and riding bow wave (7) Rest/milling: lying motionless at surface (logging) or slow,
synchronous surfacing.
Recording of other seabirds was carried out on the majority of trips. Each seabird observed
within an assumed strip width 500m either side of ahead was counted once only, with
sightings grouped into minute periods. For each seabird sighting the following recordings
were made: species name, number seen and age. Notes on behaviour were also made
including associations with fishing vessels, cetaceans, and environment effects such as oiling
and fishing net entanglement.
Effort data was collected simultaneously with sightings data to enable the number of seabird
and cetacean sightings to be scaled to recording effort. At 15 to 30 minute intervals, or
whenever the ships course changed, a range of variables were measured, including the ship's
speed and course, and sea/weather variables such as sea state and visibility (Evans, 1995).
Between June 2007 and January 2009 ~40 surveys were completed, with effort data collected
on 30 surveys (Figure 4.1, Table 4.1).
Table 4.1: Effort-related surveys in Lyme Bay and surrounding waters 2007-2009
Month
January
February
March
April
May
June
July
August
September
October
November
Total
2007
35
199
426
373
1033
2008
2009
219
616
546
343
473
513
245
445
225
211
2112
Type
Opportunistic
NE surveys
NE surveys
NE surveys
Opportunistic
Opportunistic
Opportunistic
Opportunistic
Opportunistic
Opportunistic
Opportunistic
1724
22
Total
219
616
546
343
473
548
444
871
373
225
211
4869
These data were entered into a geographic information system (GIS) created in ESRI
ARCview 3.3. The latitude and longitude of all bird sightings (from timings) were calculated
using a formula in MS Excel.
4.2 Natural England funded surveys
A systematic survey of central Lyme Bay where White-beaked Dolphins had recently been
recorded was completed between February and April 2009. A sampling grid was
superimposed over the area of past sightings and a series of 42-km long north-south tracklines
each 8-km apart was established. Because White-beaked Dolphins were not seen, the search
area was extended to other possible suitable habitats including a spawning ground for two
known important prey sources, Cod and Whiting, south of Prawle Point. In total more than
1000km of trackline was sampled on seven dates in areas with post-2006 records of Whitebeaked Dolphin.
On each survey, effort related line transect (distance sampling) was carried out, as described
in the previous section. Additionally, when a dolphin group was encountered sampling was
suspended and the group followed (‘off transect’) in an attempt to photograph each animal
present for photo-identification purposes. Once this had been done, the boat returned to the
track line to complete the days sampling. Photo-identification was carried out using a range
of Nikon and Canon digital SLR camera equipment. A further modification was that seabird
behaviour (other than for Balearics) was categorised as either Flying or Sat on the Sea.
Two additional effort-related surveys were conducted to search for winter presence of
Balearic Shearwaters in Lyme Bay, the first trip targeted around Portland Bill and the second
inshore waters between Berry Head and Exmouth. The latter survey also covered part of the
core area for White-beaked Dolphin. Total survey effort on Natural England surveys is
shown in Figure 4.1 and Table 4.1.
Figure 4.1: Effort-related surveys in Lyme Bay 2007-2009 (red = NE funded surveys in 2009, green = other)
23
4.3 Land-based counts of Balearic Shearwater
All land-based counts of Balearic Shearwater for Lyme Bay and the rest of the UK were
collated through the SeaWatch SW project, managed by Russell Wynn of the National
Oceanography Centre, Southampton. Coverage from land is considered good as there are a
number of sites where seawatching effort is high including Berry Head, Chesil Beach,
Dawlish Warren, Hope’s Nose, Portland Bill, Prawle Point, Seaton, West Bay and West
Bexington.
4.4 Overlaying sightings with environmental data
Data on water depth were extracted from the Seazone Hydrospatial British Geological Society
Digibath 250m resolution data set supplied by NE. A digital map of sediment classes in the
survey area was obtained from the British Geological Survey. All data were imported into a
GIS, ArcView 3.2 (ESRI 1999) to form the basic environmental coverage on which analyses
with at-sea sightings data were based.
Sightings-specific weekly and where available daily sea surface temperature (SST)
composites for Lyme Bay at 1-km square resolution were obtained from NERC Earth
Observation Data Acquisition and Analysis Service (NEODDA) managed by NERC &
Plymouth Marine Laboratory
http://www.neodaas.ac.uk/data/comp_browse/index.php?palette=rsg_col&dir=avhrr/time_seri
es/pa/weekly_all/sst/
Mean distance from shore of sightings were calculated using Memory Map Ordnance Survey
2004 software.
4.5 Stakeholder engagement
Casual records of Balearic Shearwater, White-beaked Dolphin and other cetaceans were
collected from skippers, wildlife recorders and recording organisations including the Devon
Wildlife Trust. In an effort to increase the number of records submitted by the public, a
postcard survey was launched for Lyme Bay dolphins and shearwaters and a website
established to enable online submission of data (see below). In particular the postcard survey
was specifically targeted at fishermen, recreational dive and angling boats and yachtsmen.
Figure 4.2 Dolphin and shearwater postcard surveys
24
Figure 4.3 Data entry and reporting functionality of new web pages to capture sightings from local skippers and
members of the public
Meetings were held with representatives from the recreational angling boat and commercial
fishing communities to explore ways of promoting the project and encouraging improved
relations with conservation bodies. One important objective was to explore ways in which
relations with fishermen and other stakeholders impacted by the scalloping ban could be
improved, including whether there was any potential for fishermen to become involved in
ecotourism.
In addition a VIP boat trip to look for White-beaked Dolphin provided an opportunity for
senior Natural England staff to meet with representatives from the fishing community and
other stakeholders involved in marine economic activity and research in Lyme Bay.
5.0 Results
5.1 Balearic Shearwater
5.1.1 Effort-related observations from sea
63 at-sea sightings of 105 birds were collected from June 2007 to April 2009, including 33
sightings of 63 birds on effort related surveys (Figure 5.1, Table 5.1). 74% of sightings were
of singletons, including a bird in flight on Natural England surveys in February 2009. Birds
seen at sea in the wider Channel are illustrated in Appendix 1.
25
1
2-9
10-19
20-50
51-99
100 or more
Figure 5.1: Balearic shearwaters recorded in Lyme Bay from effort-related and casual surveys. Closed circles
are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the
number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as
red dotted lines.
67% of sightings were categorised as flying birds (n=22), 21% (n=7) were observed
scavenging around boats, whilst the remaining 12% were seen sat on the sea. Of the seven
scavenging sightings, four were around angling boats, two around beam trawlers whilst one
bird was noted around a pelagic trawler. Balearic Shearwaters scavenged amongst a range of
other seabirds including Razorbills, large gull species, Great Skuas and Fulmars. As in
previous years, birds seen in association with fishing boats were tame at times and swam
within a few metres of boats. Whilst scavenging, there was no evidence to indicate that
Balearic Shearwaters were being unduly harassed by large gull species or other seabirds. In
addition to scavenging behaviour, birds were also seen diving for fish around these boats,
though encounters did not identify which prey species the birds were feeding on.
Balearic Shearwaters did not linger as long as other seabirds (e.g. Herring Gull, Kittiwake and
Fulmar) around fishing boats if discard was not readily available.
In both 2007 and 2008 the main concentrations of birds found were around Portland Bill. The
birds were chiefly seen either (1) scavenging around angling and fishing boats, (2) flying past
Portland Bill (up to 10 in a single flock) or (3) sat on the sea in small flocks (up to eight) up to
11.5km to the south-west (Figure 5.1).
26
Table 5.1: Monthly summary of Balearic Shearwater sightings
Month
January
February
March
April
May
June
July
August
September
October
November
December
Total
No. per 100 Km on
effort surveys
0
0.2
0
0
0
0
12.4
0.5
0.8
0
0
n/a
2.2
No.
sightings
0
1
0
2
0
1
40
12
5
3
0
n/a
63
No.
counted
0
1
0
2
0
1
79
15
5
3
0
n/a
106
Flock
size range
0
1
0
1
0
0
1-10
1-3
1
1
0
n/a
1-10
Survey effort has not been even across Lyme Bay, so the results need to be treated with
caution. For example, in 2008 land-based records were more numerous in the western Bay
and it is possible that coastal aggregations (e.g. in Tor Bay, Berry Head and off Exmouth)
may have been missed in this area due to under-sampling.
Away from Portland Bill birds were only seen in one’s and two’s, either in flight or
scavenging around angling/fishing boats.
Only a single Balearic Shearwater was seen on Kerr-McGee surveys in 1994/1995 providing
further evidence to indicate that this species has increased in the region over the last 15 years.
5.1.3 Land-based counts
5.1.3.1 Balearic Shearwaters in Lyme Bay prior to 2007
A study by Wynn et al. (2007) collated all archive data for Balearic Shearwater from UK and
Irish waters. Prior to 1980, the main area in Lyme Bay where the species was recorded was
Portland Bill. Records stretching back to the 1950s indicated that average annual totals of
birds seen at this site were less than 150. However, short-term influxes occurred between
1958 and 1961 and between 1977 and 1980. Several hundred birds per year were recorded
during these two periods, with day totals of up to 620 birds peaking in late summer and early
autumn. Many of these records referred to birds foraging offshore or undertaking small-scale
foraging movements, both off Portland Bill and in Chesil Cove. These two influxes were
likely driven by 1) short-term disruptions in prey availability in areas further south, e.g. the
French Biscay coast, where a large proportion of the World population traditionally gather to
moult between July and October, and/or 2) increased prey concentrations in eastern Lyme
Bay.
Since 1980, numbers of Balearic Shearwaters recorded annually in Lyme Bay have been
about 30-40% of the UK and Irish total (this proportion has remained reasonably constant up
to the present day). Annual totals remained at a relatively low level through the 1980s, but
started to dramatically increase from the mid-1990s onwards. Numbers have remained
elevated since then, albeit with marked inter-annual variability (Wynn et al., 2007; Wynn et
al., 2009). The total number of birds reported off Portland Bill exceeded 300 in three years
between 1998 and 2006, and approached 750 in 1998. The majority are seen between July and
27
October, e.g. 85 on 29 July 1998, up to 90 lingering offshore in July 2001, and 77 on 12 Sept
2006.
5.1.3.2 Balearic Shearwaters in Lyme Bay in 2007-08
During 2007 a total of 193 records were received for the Lyme Bay area (Figure 5.3). The
majority of records came from Portland Bill (91), Prawle Point (21) and Berry Head (20).
These three sites alone contributed 132 records (or 68% of the total). The only other site with
more than ten records was Seaton. The largest day totals (50+ birds) are listed below:
117 off Portland Bill on 8 July.
90+ off Portland Bill on 5 July.
88 off Portland Bill on 9 July.
74 off Portland Bill on 20 July.
52 off Portland Bill on 22 June.
50 off Portland Bill on 25 June.
A further 40 records of 10-49 birds were received.
During 2008 a total of 313 records were received for the Lyme Bay area (Figure 5.4). The
majority of records came from Portland Bill (130), Berry Head (53) and Dawlish Warren (49).
These three sites alone contributed 232 records (or 74% of the total). Other sites with more
than ten records included Prawle Point and Seaton. The largest day totals (50+ birds) are
listed below:
109 off Berry Head on 16 Aug.
83 off Berry Head on 18 Aug.
66 off Portland Bill on 1 Sept.
60 off Portland Bill on 4 July.
50 off Portland Bill on 13 Jan.
A further 63 records of 10-49 birds were received.
The temporal distribution of records is illustrated in Figure 5.2
Balearic Shearwater records in Lyme Bay (2007-08)
2007
2008
80
70
60
50
40
30
20
10
0
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Month
Figure 5.2: Temporal distribution of Balearic Shearwater records in Lyme Bay during 2007-08
28
January 2007
April 2007
February 2007
May 2007
March 2007
June 2007
July 2007
August 2007
September 2007
October 2007
November 2007
December 2007
Figure 5.3: Monthly sightings of Balearic Shearwaters in 2007
29
January 2008
April 2008
July 2008
October 2008
February 2008
May 2008
August 2008
November 2008
Figure 5.4: Monthly sightings of Balearic Shearwaters in 2008
30
March 2008
June 2008
September 2008
December 2008
The above graph shows that the majority of records were received in the period from June to
October, although in 2008 over 40 records were also received for January.
Not all records specify behaviour, e.g. foraging, roosting or migrating, but analysis of those
that do reveals some overall patterns. Off Portland Bill, many of the birds seen during June
and July were lingering offshore or undertaking local (post-roost) foraging movements. This
was particularly evident in 2007, when up to 117 birds were seen for several weeks, with most
showing obvious signs of active wing moult. Up to 2500 Manx Shearwaters were also
regularly recorded at this time. The largest counts involved birds moving west early in the
morning, indicating that they were roosting somewhere east of Portland Bill. Later in the
summer and autumn most birds were seen moving west as part of larger-scale foraging
movements. The influx in January 2008 also involved birds foraging offshore or moving west,
in association with thousands of Razorbills and other seabirds.
Off Seaton most birds are seen moving west, while off Berry Head most birds are moving
south (as with other seabirds), although small numbers of birds (up to ten) are occasionally
seen feeding offshore or following trawlers as they return to Brixham. Off Dawlish Warren
small numbers (typically up to ten birds) are usually seen self-foraging in association with
gulls, terns and other seabirds.
5.2 White-beaked Dolphins in Lyme Bay
5.2.1 Sightings between 2006 and 2009
Over the period July 2006 to April 2009 twenty sightings of ~300 individual White-beaked
Dolphins were recorded in Lyme Bay. Eleven of the sightings were classed as casual records
and came from a variety of sources, including two sightings through ‘unidentified dolphins in
Lyme Bay’ videos posted on youtube by yachtsmen. Of the casual records, two of the
sightings did not have an exact date and one of these was lacking a precise position.
Nine sightings were recorded on effort-related surveys (Figure 5.5). On effort-related surveys
White-beaked Dolphins were the second most frequently seen species (after Harbour
Porpoise) accounting for approximately a fifth of all cetacean sightings. There were no
sightings during effort-related Natural England surveys in the late winter/early spring period
of 2009 and it was thought that the animals were not regularly in Lyme Bay over that period.
Table 5.2: Monthly summary of White-beaked Dolphin sightings
Month
January
February
March
April
May
June
July
August
September
October
November
December
Total
No. per 100 Km
on ‘effort’ surveys
5.5
0
0
0
0.6
0
0
2.1
1.1
0.9
2.4
n/a
0.9
No.
Sightings
2
0
1
1
1
2
5
4
2
1
1
n/a
20
No.
Counted
12
0
3
4
3
7
33
220
4
2
5
n/a
293
31
Group size
range
5-7
0
3
4
3
3-4
1-20
2-200
2
2
5
n/a
1-200
White-beaked Dolphin sightings were recorded in all months except December (no survey
effort in this month) and February (presumed absent February 2009) (Table 5.2). The
majority of casual records were seen from June to August, reflecting the peak season for
yachting, whilst effort-related records were more evenly spread through the year.
Figure 5.5: White-beaked dolphins recorded in Lyme Bay 2006- 2009 from effort-related surveys and casual
records. Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the
circle indicates the number of dolphins recorded. Depth contours shown in blue and are 10m, 20m and 50m.
Survey effort is shown as red dotted lines. Background shading indicates main sediment type.
77% of sightings were of 2-5 animals, with the only groups comprising more than 10
individuals being of 15, 20 and ~200. The latter group was seen by Colin Speedie in August
2008. All of the animals sighted on effort related surveys were similar in size, though on
casual surveys there were two smaller animals thought to be juveniles in a group of three off
Lyme Regis in March 2008.
White-beaked Dolphins preferred the central deeper waters of Lyme Bay, with nearly 90% of
records being in waters 45-51m deep. Water temperatures ranged from 8.8 to 17.3ºC, with
the model class being 15 ºC and no records in the 11-12 ºC category (Figure 5.6).
95% of sightings were offshore (>2km), the sole land-based observation being from wellwatched Berry Head in April 2009. This sighting represented the first observation for the
sites’ principal seawatcher Mark Darlaston, highlighting the relative rarity of the record. Two
of the three near shore sightings were in the spring. For effort-elated sightings, the preference
for offshore waters was even more apparent with sightings being in the range 16-36km (mean
29km) from land.
32
% of all sightings
30
25
20
15
10
5
0
8
9
10 11 12 13 14 15 16 17 18
Sea Surface Temperature Category (ºC)
Figure 5.6: Water temperatures in 1-km squares where White-beaked Dolphins were recorded
Most of the White-beaked dolphin sightings were over predominantly sandy sediments rather
than other sediment types (Figure 5.5). In deeper central waters of Lyme Bay, a front (that
runs from Portland Bill to Start Point) forms during the summer months (Figure 2.2.
Anecdotal records from local angling skippers indicate this area of Lyme Bay supports shoals
of Whiting during July and August and has been good for Cod around wrecks over the last
four years (Ian Cornwell and Chris Caines pers. comm.) aided by strict quotas.
5.2.2 Co-occurrence with other cetacean species
Harbour Porpoises were regularly recorded in the central areas of Lyme Bay in the same
months as White-beaked Dolphin.
Few other species were seen when White-beaked
Dolphins were around, although there were two records of Common Dolphin, both during the
winter months when sea surface temperatures were cold (Figure 5.7).
Figure 5.7: Cetacean sightings in months when white-beaked dolphins were recorded in Lyme Bay 2007-2009.
Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. Sightings
on survey effort are shown as squares. Casual sightings are shown as circles. White: Bottlenose dolphin;
Yellow: Common dolphin; Red: Harbour porpoise; Green: Pilot whale; Blue: White-beaked dolphin.
33
In months when White-beaked Dolphins were absent, Harbour Porpoise, Common Dolphin
and Bottlenose Dolphin were recorded on a number of occasions in the central areas of Lyme
Bay (Figure 5.8). These results suggest that there may be competitive interaction and habitat
partitioning between Bottlenose Dolphin, Common Dolphin and White-beaked Dolphin (see
discussion). In particular the sudden disappearance of White-beaked Dolphin in February
2009 (following regular presence for at least nine months) coincided with the arrival of a
large pod of Bottlenose Dolphins.
Figure 5.8: Cetacean sightings in months when white-beaked dolphins were not recorded in Lyme Bay 20072009. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines.
Sightings on survey effort are shown as squares. Casual sightings are shown as circles. White: Bottlenose
dolphin; Yellow: Common dolphin; Red: Harbour porpoise; Brown: Minke whale.
5.2.3 Association with seabirds
There were no instances of foraging seabirds (e.g. Gannets, gulls) associating with schools of
White-beaked Dolphin, indicating that the species does not principally feed on shoals of fish
swimming near the surface. The presumed main prey items, white fish and shellfish, are
thought mainly to occur in the lower half of the water column (i.e. >25m deep), which are not
targeted by plunge diving/surface feeding seabirds.
5.2.4 Other recent records of White-beaked Dolphin in the Channel
Seven animals were seen off Dungeness Kent in December 2004 (the first record for reserve
warden David Walker who has been seawatching daily at the site since 1989). Seven sightings
were made in coastal areas off the Cornish coast between 1990 and 2004. The records
spanned from Gwennap Head in the west to Looe in the east and were all made in July and
August (Goodwin et al. 2007).
Recent records supplied to Seaquest included 8-10
individuals in the middle of Lyme Bay (DWT) in August 2004, and 20 in Fal Bay, Cornwall
and 2 off Nare Head, Cornwall both on the 29th September 2005.
On the French side, there were just five sightings up to 2002, although there were reports of
regular sightings by fishermen in northern France, especially during the winter months
(Kiszka et al. 2004). Three were seen off Cap Gris-Nez, Nord pas de Calais in October 2008
(Source: (http://www.trektellen.nl/). The sole report off the Normandy coastline (where there
34
are hundreds of sightings of other species) relates to a group of ~100 off Jersey in January
1985 (François Gally, Groupe d’Etude des Cétacés du Cotentin pers. comm.)
No White-beaked Dolphins were seen on the four effort related systematic surveys that have
been carried out in the Channel in recent years - Scans (1994), Scans II (2005), Kerr-McGee
Oil (1994) or JNCC SAS surveys (1994, see White et al. 1995).
Figure 5.9: Casual sightings of White-beaked Dolphin post 1985 (excluding Lyme Bay records post-2005)
5.2.5 Photo-Identification catalogue
A catalogue of uniquely marked White-beaked Dolphins (n=6) and Bottlenose Dolphins
(n=24) photographed in Lyme Bay and surrounding waters was established under the project.
The catalogue can be downloaded from http://www.marine-life.org.uk/coastallatest.html
A project is currently being established with co-workers in the Netherlands and
Northumberland to expand the White-beaked Dolphin catalogue into the North Sea – the
nearest known region where the species regularly occurs off eastern Britain.
A uniquely marked White-beaked Dolphin - note the horizontal scratches on the leading edge of the dorsal fin
(Photo: James Phillips).
35
A photo-identification catalogue of Bottlenose Dolphins from Normandy has recently been
compiled, comprising in excess of 200 individual animals. Rather surprisingly, preliminary
inspection of the catalogue of Bottlenose Dolphins supplied by Marinelife has not yielded any
recaptures, although further analysis work is required (Francoise Gally, GECC pres. comm.).
5.3 Other seabirds recorded in Lyme Bay 2007-2009
Over the ~50 effort-related surveys between 2007 and 2009 there were 4250 seabird sightings
totalling 43,200 birds of 33 species. 15,530 birds of 30 species were recorded on the nine
Natural England surveys from February to April 2009 (Table 5.3).
Table 5.3: Seabird sightings in Lyme Bay seen on Natural England surveys from February to April 2009
Cetaceans
Red-throated Diver
Great Northern Diver
Black-throated Diver
Great Crested Grebe
Fulmar
Balearic Shearwater
Great Shearwater
Manx Shearwater
Gannet
Cormorant
Shag
Brent Goose
Shelduck
Common Scoter
Great Skua
Pomarine Skua
Herring Gull
Lesser
Black-backed
Gull
Great
Black-backed
Gull
Kittiwake
Large Gull spp.
Black Headed Gull
Common Gull
Mediterranean Gull
Sandwich Tern
Common Tern
‘Commic’ Tern
Guillemot - sea
Guillemot - land
Razorbill
Puffin
Auk sp.
14/2
3
6
1
32
76
1
18
19/2
24/2
6
28/2
2
2
15/3
1
4
21/3
2
2
1
33
1
1
15
54
19
32
539
1
1
206
309
1
2
2
143
3
260
1
1
1
2
2
171
4
1046
23
30
10
75
55
85
117
7
11
26
29/3
1
2
1
21
11
21/4
21/4
40
40
14
106
4
88
45
117
2
4
34
1
1
Total
9
26
1
22
276
1
1
63
1790
13
136
8
1
54
14
1
3533
253
3
6
7
2
5
5
30
2
658
29
378
445
136
471
256
19
7
4
1
78
32
6
88
54
70
25
27
74
474
14
96
30
64
25
2
81
22
1
1
2
3
12
3
455
81
19
20
11
13
7
6
5223
1500
973
9
537
6
4
12
429
738
866
1352
591
567
450
210
74
137
30
14
555
1000
30
143
113
126
130
7
2
7
1
7
6
107
7
1
9
18
500
21
8
* = off transect, but seen nearby by local skippers/other observers
Seabird highlights from the surveys included:
•
The regular occurrence of moderate numbers (maximum day count 76) of foraging
European Storm-petrels in offshore waters (>3km out) during the summer/early autumn
months, especially in central and eastern areas of the Bay (Figure 5.10). This represents a new
finding, as Lyme Bay has not been sampled for European Storm-petrels before by the JNCC
Seabirds at Sea Team and few were seen during the Kerr-McGee surveys in 1994/5.
36
Figure 5.10: European Storm-petrels recorded in Lyme Bay from effort-related and casual surveys. Closed
circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates
the number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown
as red dotted lines.
•
The regular occurrence of moderate numbers (maximum day count 36) of scavenging
Great Skuas in offshore waters (mostly >10kmfrom land) during the summer/early
autumn months (Figure 5.11).
Far fewer were seen on Kerr-McGee surveys
suggesting that this species has increased in Lyme Bay since the mid-1990s. This is
supported by coastal sightings data from Hampshire (Wynn 2008).
Figure 5.11: Great Skuas recorded in Lyme Bay from effort-related and casual surveys during the summer
months 2007-2008. Closed circles are sightings from effort surveys while open circles are casual sightings. The
size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m and
50m. Survey effort is shown as red dotted lines.
37
•
The winter presence of small numbers (maximum day count 5) of Great Skua in
offshore areas (>10km from land) (Figure 5.12). This represents a westerly range
extension to that previously documented (Stone et al. 1995).
Figure 5.12: Great Skuas recorded in Lyme Bay from Natural England effort-related and casual surveys in the
early winter period 2009. Closed circles are sightings from effort surveys while open circles are casual sightings.
The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m
and 50m. Survey effort is shown as red dotted lines.
•
Large numbers of wintering Guillemots widely distributed across Lyme Bay (Figure
5.13). A crude analysis of the data (mean no./km2 * area Lyme Bay) suggests an
approximate abundance estimate of 16,000 Guillemots in February 2009 in Lyme Bay.
Birds were equally abundant in surrounding waters, and the wider population is likely
to be considerably larger. The abundance estimate for Lyme Bay indicates that the
area may be may be nationally important for Guillemot, as the total would represent
~1% of the UK wintering population, assuming the winter population is of a similar
order to the breeding population which has been estimated at 1.3 million birds
(Seabird 2000 data). The results concur with the findings of the Kerr-McGee study
which estimated a wintering population in February 1994 of ~16,000 Guillemots
within the sampled areas of Lyme Bay, suggesting there has been little change in
wintering status since 1994.
•
Though less abundant than Guillemot (25% fewer), substantial numbers of Razorbills
were also recorded during the winter months, especially off Portland Bill. A crude
abundance estimate of 4,000 Razorbills was made for Lyme Bay in February 2009,
which was also the same as the abundance estimate from the Kerr-McGee study in
1995 and would qualify Lyme Bay as being nationally important (see criteria for
Guillemot).
38
Figure 5.13: Distribution and relative abundance of Guillemots in Lyme Bay on Natural England surveys during
the early winter period in 2009. Closed circles are sightings from effort surveys while open circles are casual
sightings. The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are
10m, 20m and 50m. Survey effort is shown as red dotted lines.
•
Several rare species were seen, most noteworthy amongst them being a Great
Shearwater on Natural England surveys in February 2009. This is only the seventh Dorset
record and the first during the winter. Furthermore, it may also represent the first occurrence
of the species in British waters in February.
•
Further comparisons with data collected for the Kerr-McGee indicates that Kittiwakes
have decreased, whilst Sooty Shearwaters have increased.
5.4 Other cetaceans seen recorded in Lyme Bay 2007-2009
5.4.1 Effort related sightings
38 sightings of three other cetacean species were recorded on effort-related surveys. The
species were Bottlenose Dolphin, Common Dolphin and Harbour Porpoise. On Natural
England surveys there were 19 sightings of Harbour Porpoise, plus single sightings of
Bottlenose Dolphin and Common Dolphin, whilst on other effort-related surveys there were a
further 15 sightings of Harbour Porpoise, plus singles of Bottlenose Dolphin and Common
Dolphin (Table 5.4).
Amongst the sightings, of particular significance was (1) the regular presence of Harbour
Porpoise in all seasons in offshore waters (Figure 5.130) and (2) a large pod Bottlenose
Dolphins in the middle of Lyme Bay during February 2009 comprising a high proportion of
mother/calf pairs, suggesting the areas is used as a nursery ground.
39
Table 5.4: Effort related cetacean sightings in Lyme Bay 2007-2009
Month
January
February
March
April
May
June
July
August
September
October
November
Total
Bottlenose
Dolphin
No.
Sightings
Bottlenose
Dolphin
No.
Counted
1
44
1
2
Common
Dolphin
No.
Sightings
1
Common
Dolphin
No.
Counted
5
1
2
Harbour
Porpoise
No.
Sightings
2
10
7
2
6
Harbour
Porpoise
No.
Counted
5
17
12
2
7
3
3
1
19
3
2
1
67
6
50
2
34
The presence of inshore sightings of Bottlenose Dolphin and offshore sightings of Harbour
Porpoise concur with the results found during the Kerr-McGee study (Leaper et al. 1995) in
1994/5 (Figure 5.15).
Figure 5.14: Harbour Porpoise effort-related sightings from Marinelife surveys in Lyme Bay during the summer
(Apr-Sep) and winter (Oct-Mar) months 2007-2009. Red circles are summer sightings, blue circles are winter
sightings. Circle sizes are scaled to the number recorded. Depth contours are shown in solid blue lines and are
10m, 20m and 50m. Summer survey effort is shown as red dotted lines, winter survey effort is shown as blue
dotted lines. Background shading indicates main sediment type
40
Figure 5.15: Cetacean sightings on monthly Kerr-McGee transects in 1994. Left side - Bottlenose Dolphin, Right
side – Harbour Porpoise (Source: Leaper et al. 1995).
5.4.2 Casual sightings 2007-2009
50 casual sightings of six cetacean species were collated, chiefly from skippers of local dive,
angling and fishing boats following direct contact. These comprised 24 sightings of
Bottlenose Dolphin, 17 of Common Dolphin, 5 of Harbour Porpoise and singles of Risso’s
Dolphin, Minke Whale and Long-finned Pilot Whale.
The most obvious difference between casual and effort data was the low proportion of casual
Harbour Porpoise sightings received, indicating this species is overlooked by non-experts
with busy jobs at sea.
37 of the casual sightings (Figure 5.16) were obtained during a three month period through
the Natural England project (postcards, website etc), highlighting the potential to encourage
data flow and interest amongst local skippers with modest resource investments. Very few of
these sightings were being captured elsewhere demonstrating that the work complements
rather than duplicates existing sightings schemes.
1
2-9
10-19
20-50
51-99
100 or more
Figure 5.16: Casual sightings of cetaceans in Lyme Bay in 2009 obtained through the Natural England project.
The size of the circle indicates the number of cetaceans recorded. Depth contours shown in blue and are 10m,
20m and 50m. White: Bottlenose dolphin; Yellow: Common dolphin; Red: Harbour porpoise; Blue: White-beaked
dolphin.
41
5.5 Stakeholder engagement
5.5.1 Postcard distribution
The postcards were distributed to 185 skippers of angling, diving and leisure boat trips across
southwest England (42 in Hampshire, 70 in Dorset, 51 in Devon, and 22 in Cornwall).
Figure 5.17: Location of ports (yellow crosses) where postcards have been distributed to local skippers
The postcards were also distributed to 44 Sailing Clubs across Cornwall and Devon (21
Cornwall and 23 Devon), with more planned for Hampshire and Dorset.
Figure 5.18: Location of sailing clubs (yellow crosses) where postcards have been distributed to local skippers.
Note: Planned distribution = red crosses.
5.5.2 Fishermen impacted by the ban on scallop dredging
Due to the current sensitivities between scallop dredging fishermen and Natural England/the
Devon Wildlife Trust only limited progress was made in liaison work. The advice from a
number of stakeholders was to ‘let thing settle down’ and avoid making contact with scallop
dredging fishermen, although some indirect contact was made.
42
In spite of this limitation, a number of conclusions can be drawn from the round of
discussions with fishermen, representatives from fisheries organisations and recreational dive
boat owners, including:
•
It is considered that there is currently very limited potential for scallop fishermen to
diversify and take the public out on marine wildlife trips. The combined costs of fuel,
crew and insurance would likely to make this prohibitively expensive for paying
passengers. Furthermore, these boats were not particularly well designed for carrying
passengers e.g. often no toilet facilities on board. The market is likely to be too small
to enable a complete business change from fishing to ecotourism.
•
Anecdotal feedback from several fishermen contacted (admittedly not scallopers)
thought there was no need to find alternative sources of income, as local scallopers
had found new and productive fishing grounds away from the exclusion zones. There
was a concern in this respect, that the ban may be counter-productive forcing
scallopers to move into even more sensitive marine areas, including pristine areas
never dredged before.
•
There is a need for less technical language when engaging the fishing community with
conservation plans and issues. This is likely to lead to improved understanding and
better relations in the long-term.
•
Interest in marine wildlife amongst local skippers is high, and there is considerable
potential to develop this interest further through engagement activities. There are
likely to be benefits in doing this work, as (1) it is likely to develop a greater interest
and understanding for marine wildlife in conservation amongst skippers in the longterm and (2) to provide feedback to conservation bodies on current issues concerning
local skippers.
6.0 Discussion
6.1 Importance of Lyme Bay for Balearic Shearwater
The analysis of land-based sightings collected through SeaWatch SW indicates that
internationally important numbers of Balearic Shearwaters are currently visiting Lyme Bay,
and the area in recent years has held about a third of the annual UK and Irish total. The total
known breeding population is about 2000-2500 pairs (restricted to the Balearic Islands in the
Mediterranean Sea), but counts outside the breeding season suggest a total population in
excess of 20,000 individuals. Three-figure counts of Balearic Shearwaters have regularly been
made in Lyme Bay in recent years, indicating that up to 0.5% of the World population may be
present in this small area at any one time. There are also indications that numbers utilising
Lyme Bay, and southwest UK in general, are increasing (Wynn and Yesou, 2007; Wynn et
al., 2007; Wynn et al., 2009), probably in response to climate and fisheries-driven changes in
prey availability (typically small shoaling fish, e.g. Anchovy, Sprat, Sardine).
Portland Bill is (historically and presently) an important foraging area for this species, both
during the mid-summer moulting period (as in June-July 2007) and in mid-winter (as in
January 2008). Offshore surveys have confirmed the relatively high importance of Portland
Bill relative to other sampled areas, although parts of Lyme Bay are under-recorded.
43
The number of birds utilising Lyme Bay show marked inter-annual variability, probably in
response to local changes in prey distribution from local through to regional scales. For
example, very few birds were seen in January 2007, and the mid-summer moulting
aggregation was 50% smaller in 2008 than 2007. Dawlish Warren also appeared to be a
favoured foraging area in both late summer and autumn 2007 and 2008, although numbers of
birds seen here are typically only in single figures. It should be noted that this analysis is
based upon casual sightings data, not effort-based data. There may be other sites within Lyme
Bay that receive limited observer coverage but are still important foraging areas for Balearic
Shearwaters. Small boat surveys in recent years have indicated that few birds are present
away from the coastal zone, but more comprehensive coverage of near shore sites may reveal
previously unknown foraging areas.
Large-scale foraging movements probably encompass the entire western English Channel,
and are most commonly observed between July and October. During such movements, most
birds are seen moving west off Portland Bill and through Lyme Bay, before turning south as
they reach the western bay off Berry Head and exiting to the west off Prawle Point.
It should also be noted that high counts from land-based seawatching sites at times are
associated with fresh to strong south/south-west winds and are often followed by far lower
counts in subsequent more settled conditions. Given that relative few have been seen at sea in
Lyme Bay despite a fair amount of survey effort, these data may indicate that many of the
birds seen are wind-driven/assisted from more substantial numbers regularly present in
coastal waters of northern France. At Gatteville Normandy, located at the north-east corner
of the Cherbourg Peninsula and Cap de la Hague, in the north-west corner, large Balearic
Shearwater counts coincide with moderate to strong south west winds (e.g. 482 at Gatteville
7/9/2008, wind SW 5 and 109 at Cap de la Hague 3/9/2006 wind SW4), which support the
theory that birds are being displaced (or undertaking wind-assisted foraging flights)
north/north-east from the Normandy and Brittany coastlines. Thus high day counts from land
can give a false impression of how many birds are regularly utilising Lyme Bay to moult and
feed over the summer months
Potential threats to the species in UK waters include oil spills, recreational disturbance,
offshore windfarms and fisheries bycatch. Although none of these threats has significantly
impacted birds using Lyme Bay to date, the oil spill associated with the MSC Napoli
grounding in Jan 2007 would almost certainly have affected Balearic Shearwaters if it had
occurred a few months later.
6.2 Possible reasons why the Portland Bill area is
important for Balearic Shearwaters
The sea area to the south-west of Portland Bill is characterised by a tidal front, where food
sources including shoaling fish and plankton are likely to be aggregated. The main offshore
features in close proximity to Portland Bill are Portland Race and the Shambles Bank.
Portland Race is an area of rough water formed by the combined effects of a westerly tidal
flow forcing deep water to spill over a shallow reef and a southerly tidal flow diverted by the
Isle of Portland. Where the two meet a confused sea state is created. The area is good for
Bass fishing and attracts a number of angling boats which use Sandeels and Mackerel as bait,
providing opportunities for scavenging by Balearic Shearwaters. The Shambles Bank east of
Portland Bill supports large shoals of Sandeels in the summer months and is heavily fished by
commercial and private angling boats, providing good opportunities for self-foraging and
scavenging by Balearic Shearwaters. Additionally, in recent years, anecdotal evidence from
44
anglers is that large shoals of Anchovies, a known vitally important food source for Balearic
Shearwaters, have been present in the vicinity of Portland Bill. The presence of shoals of
Anchovies may possibly be key in explaining presence and inter-annual variability though
precise information on the local occurrence of this prey species is difficult to obtain, as they
currently have a higher economic value than similar-sized fish which also occur, hence
information is commercially sensitive.
The highest numbers of Balearics recorded in the Portland Bill area over the study period
were in early July 2007. A feature of this period was that the seas were heavily stirred up,
evidenced by high Total Suspended Matter concentrations (a turbidity measure) (Figure 6.12)
that in themselves have been linked to enhanced biological productivity (Sverdrup et al.,
1942; Emery et al., 1973). This combined with warm water temperatures (16-18.3C) is likely
to have provided suitable conditions for pelagic shoaling fish. The turbid waters may have
also made prey items easier to catch. Plunge divers need to be able to see their prey below the
surface, whereas pursuit divers such as the Balearic Shearwater may benefit from increased
turbidity, which prevents the prey from seeing them coming (Baduini et al. 2003).
Figure 6.1: Elevated Total Suspended Matter concentrations (a turbidity measure) concentrations off Portland Bill
in early July 2007. (Source: Plymouth Marine Lab)
6.3 Importance of Lyme Bay for White-beaked Dolphin
The results from Marinelife surveys and collation of casual records over a longer period and a
wider area confirm that since at least 2005 and stop press again in summer 2009 Whitebeaked Dolphins have regularly visited Lyme Bay at all times of the year, but especially
during the summer months. Canning (2007) found White-beaked Dolphin to be primarily a
summer visitor to the deeper waters off Aberdeen, north-east Scotland with occurrence
coinciding with calving and groups containing calves.
Lyme Bay is the most southerly known site in Europe where White-beaked Dolphins
regularly occur. In Lyme Bay up to 200 animals have been seen on a single occasion, which
represents ~1% of the total population estimated for north-west European shelf waters,
confirming regional and possibly national importance. The available data suggest that Lyme
Bay may be the most important locality in the English Channel for White-beaked Dolphin,
though this cannot be confirmed due to under-sampling of other areas of the Channel.
45
The majority of White-beaked Dolphin encounters have been of small groups (typically 2-5),
where the animals seen have been characteristically of similar size (body length), with a
noticeable lack of calves. The timing of first occurrence (early summer when calving is
thought to mainly occur) and the lack of calves, may possibly indicate the majority of
animals present are juveniles dispersing away from calving grounds (and adult/calf groups)
to exploit seasonally abundant food sources, though sample sizes are too small to confirm
this.
The long-term conservation of White-beaked Dolphin in Lyme Bay is a cause of conservation
concern due to predicted rises in sea surface temperature (SST). White-beaked Dolphin rarely
occurs in waters >18ºC and currently waters temperatures regularly reach 17-18 ºC in Lyme
Bay in the summer months. A modest 1-2 ºC rise in SST could lead to the disappearance of
White-beaked Dolphins during the summer months. Given the current predicted increases of
water temperature around north-western Europe of up to 0.5oC per decade (Fisheries Research
Service, 2003) sea temperatures could become generally too warm in the summer months
within 20-40 years. Note though that because White-beaked Dolphin occurs in stratified
waters, sea temperatures in the lower layers where they are thought to mainly feed may be
cooler than temperatures at the surface.
Relaxation in current quota levels and renewed overfishing of white fish is a further threat.
6.4 Possible reasons why Lyme Bay is utilised by Whitebeaked Dolphin
The core area of occurrence is central Lyme Bay which is characterised by water depths of
>50m, and a gently sloping predominantly sandy seabed. A study by Canning (2007) off the
coast of north-east Scotland similarly found White-beaked Dolphins to be associated with
sandy sediments, deeper waters and gentler slopes. No other year-round specific studies
relating distribution to habitat variables have been undertaken in the UK.
The central waters of Lyme Bay mark the eastern limit of stratification in the water column
during the summer months. Further east in the Channel where White-beaked Dolphin is rare)
the waters are generally well mixed. In stratified waters, seabed temperatures where Whitebeaked Dolphins are thought to mainly feed are likely to be significantly cooler than sea
surface temperatures.
The central area of Lyme Bay is less intensively fished than many other parts of the Bay, but
is known amongst local fishermen and anglers as a good fishing area (especially around
wrecks) for Whiting and in recent years Cod in the summer months. Whiting is known to be
a key prey item for White-beaked Dolphin and although a widespread species, has a
preference for deep water sandbanks - which is a characteristic of the central areas of Lyme
Bay (the ‘French Banks’). With current quotas in place, Cod abundance in this area is
thought to be currently relatively high at present, contrasting with the collapse of Cod,
Whiting and other white fish stocks over large parts of the North Sea due to overfishing (e.g.
see ICES, 2005 for Whiting). The availability of white fish may be a key driver for the
increased number of sightings of White-beaked Dolphins in Lyme Bay, though underrecording can not be ruled out.
The occurrence of White-beaked Dolphins in Lyme Bay during the summer months in warm
sea temperatures coincides with a general absence of Common Dolphins, though both species
have been recorded together during the winter months when sea temperatures are relatively
46
cold. The Lyme Bay results are consistent with a more wide ranging analysis by MacLeod et
al (2007) of Seabirds at Sea sightings data from UK waters which demonstrated that (1)
White-beaked Dolphin is the dominant species in cold waters (<13°C) (2) White-beaked
Dolphin occurs with Common Dolphin when water temperatures are cold (<13°C) (3)
Common Dolphin is the dominant species in warmer waters (>14°C) (4) White-beaked
Dolphin has a broader temperature range in waters where Common Dolphin is largely absent
(e.g. North Sea) (Figure 6.2).
% of all dolphin sightings
100%
80%
60%
40%
20%
0%
10
10
11
12 12 13 13 14 14 15 15 16 16 17
Sea surface temperature category (oC)
11
17
18
Figure 6.2: The proportion of sightings of each species in 1oC temperature classes for summer months from
1983-1998. Black: White-beaked dolphins; White: Common dolphins. A. All sightings; B. Excluding records from
the central and southern North Sea. Source: MacLeod 2007.
An absence of Bottlenose Dolphins from central Lyme Bay may also be an important factor in
determining White-beaked Dolphins presence. The available data suggest habitat partitioning
between White-beaked Dolphin and Bottlenose Dolphin in Lyme Bay based on proximity to
land and water-depth, with Bottlenose Dolphins being a shallow water, coastal species.
Similar habitat partitioning has been demonstrated in other regions of the UK e.g.
Northumberland (Martin Kitchling pers. comm.) and north-east Scotland (Ian Sim pers.
comm.).
The occurrence of White-beaked Dolphin in Lyme Bay and other south-west waters in recent
years has coincided with a corresponding decrease in sightings of Bottlenose Dolphins (Doyle
et al. 2007). This finding may be significant although as previously mentioned underrecording of White-beaked Dolphin due to it’s preference for offshore waters cannot be ruled
out. Coastal Bottlenose Dolphins will inevitably use offshore waters from time to time.
During the Natural England surveys, a large pod of Bottlenose Dolphins (with a high
proportion of young calves) were present in the offshore central waters of Lyme Bay from
February 2009, coinciding with the sudden disappearance of White-beaked Dolphins (which
had been present for at least nine months previously).
47
6.5 Recommendations for future work
The data analysis provided in this report consists primarily of visualisation and description of
the data collected to date. Although sound progress has been made in developing an evidence
base on the offshore status of Balearic Shearwater and White-beaked Dolphin in Lyme Bay, a
number of the conclusions are tentative because sightings rates and photographic captures are
low and survey coverage has been uneven, with for example, some key areas under-sampled.
A number of recommendations are made on how the work could be developed.
6.5.1 Repeat Natural England funded transect surveys/further
analytical work
A high priority is to repeat the Natural England transects in other seasons to increase the
number of sightings and photographic captures of White-beaked and other dolphin species.
An increased number of sightings may enable abundance to be estimated by distance
sampling (subject to a sufficient number of sightings). More importantly it will enable
occurrence and abundance to be modelled with spatial (sediment type, depth, slope, aspect)
and temporal (e.g. sea surface temperature, local productivity, time of day or across the course
of the tidal cycle) variables (using generalised additive modelling (GAM) or ecological niche
factor analysis (ENFA)) both within Lyme Bay and over a wider area.
Habitat modelling may help us to: (1) Identify key areas for White-beaked Dolphin in Lyme
Bay which support the highest densities of animals (2) More precisely determine the key
habitat variables which explain White-beaked Dolphin occurrence and density in Lyme Bay
(3) Identify the species potential range in the Channel (4) Identify other potentially important
areas for White-beaked Dolphin in the Channel and to (5) Predict where White-beaked
Dolphins go when they are absent from Lyme Bay.
An increased number of photographic captures, will enable absolute abundance to estimated
by ‘mark and recapture techniques and provide improved information on a range of other
population parameters including group size, age structure, mobility, residence rates and
lifespan.
6.5.2 Targeted surveys for White-beaked Dolphin and Balearic
Shearwater
Targeted surveys are recommended: (1) To improve sample sizes of sightings and
photographic captures of White-beaked Dolphin for the analyses described in Section 6.1 (2)
To search for inshore moulting areas for Balearic Shearwaters off Portland Bill and in the
western part of Lyme Bay between Beer Head and Start Point. In coastal areas (especially in
the vicinity of Portland Bill) there is need for research work to more precisely identify how
Balearic Shearwaters utilise these areas, to identify overnight roosting areas, key prey items
and quantify the relative importance of scavenging versus self-foraging (3) To identify the
importance of different types of fishing vessel, from potters and recreational fishing boats up
to large trawlers, for scavenging Balearic Shearwaters.
Marinelife surveys have
demonstrated how few Balearic Shearwaters are generally seen on opportunistic and
systematic surveys. This was confirmed by JNCC Balearic Shearwaters surveys in
July/August 2009. Actively searching for birds is likely to be far more productive, with
fishing vessels the most likely suitable habitats. This work may also help generate an
improved population estimate of the number of birds using the Bay.
48
6.5.3 Investigating behaviour and ecology of Balearic Shearwaters
through satellite telemetry
A major step forward in helping to understand the movements and foraging behaviour of
Balearic Shearwaters in Lyme Bay and surrounding waters would be to attempt to capture a
number of individuals at sea in order to fit satellite tags. The value of this approach in
understanding seabird behaviour and ecology has been widely demonstrated (e.g. see Baduini
2008). This seems a possibility given that Balearic Shearwaters scavenge around recreational
angling boats at extremely close range and because recent research has proved it is possible to
capture bold scavenging seabirds at sea (Bugoni et al 2008))
6.5.4 Acoustic monitoring of White-beaked Dolphins and other
cetaceans in Lyme Bay
The last three years have been characterised by predominantly wet and windy weather during
the summer months, making it difficult get out to sea to undertake cetacean surveys.
Consequently gathering sightings data has proved a slow process. An alternative to recording
live sightings is to detect and log animal sound. It would be worthwhile deploying one or
more static hydrophones in the middle of Lyme Bay. Recent research undertaken by Ed
Harland (Chickerel Bioacoustics) indicates that an improved hydrophone system could be
developed and deployed for up to a month at a time to capture raw audio data (at 20 minute
intervals), which could then be processed to identify presence of the four target species
(White-beaked, Common and Bottlenose Dolphins and Harbour Porpoise). This would
provide objective new data on the relative frequency of occurrence (both through and over
days) of each of the species and enable investigation of tidal cycles, time of day and presence
of potential competitors on occurrence.
6.5.5 Developing a Lyme Bay Wildlife Officer post
There is a need to capitalise on the interest in marine animals generated amongst local
skippers through this project and the earlier work of Marinelife. One option would be to
develop a full-time roving Wildlife Officer (WLO) post. Marinelife has considerable
experience in this respect having developed the world’s first full-time wildlife office on a
commercial ferry in 2001. This role continues and the model has been adopted by other
organisations. The tasks of the WLO would include to: (1) Develop recording skills of
skippers (2) Encourage submission of sightings (3) Produce relevant interpretation material
and (4) Promote conservation/sustainability and (5) Provide feedback to stakeholders.
6.5.6 Extending White-beaked Dolphin work beyond south-west
England
It would be valuable to carry out similar photo-identification studies in other areas where
researchers regularly see White-beaked Dolphins (eg Northumberland coast and Essex coast)
to help determine the extent to which there is movement between the Channel and the North
Sea.
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8.0 Acknowledgements
We would like to thank the many skippers of dive angling and fishing boats who have made
an important contribution to this project by either providing sightings data, sponsoring
53
passage or imparting valuable insights into fishing and marine wildlife. Particular thanks must
go to Ian Cornwell (Huntress II, West Bay), Chris Caines (Tiger Lily, Weymouth), Douglas
Lanfear (Blue Turtle, Lyme Regis), Ian Noble (Samuel Irvine, Dartmouth), Jack Warmington
(NN84, West Bay), and Dave Sales (PZ77, West Bay). Thanks also to the volunteers who
have carried out surveys for Marinelife and SeaWatch SW. Special thanks here must go to
Martin Gillingham, Tony Blunden, Adrian Shephard and Mark Darlaston. Thanks to Ian
Carrier of the Southern Sea Fisheries Committee and Keith Bower of the Devon Sea Fisheries
Committee for supporting the postcard survey. Thanks to Marinelife staff Clive Martin and
Tricia Dendle for providing valuable administrative support. Finally, a special thanks for
Dave Sales and Ian Cornwell for providing invaluable advice throughout.
54
9.0 Appendices
Appendix 9.11: Balearic shearwaters recorded in the English Channel from survey and casual effort.
Closed circles are sightings from surveys while open circles are casual sightings. The size of the
circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m, 50m
and 100m. Survey effort is shown as red dotted lines.
55