SHELLFISH SURVEY OF CASTLEMAINE HARBOUR (CWOMANE

SHELLFISH SURVEY OF CASTLEMAINE HARBOUR (CWOMANE

FISHERY L E A F L E T ~ 0 . 4 6 .
SHELLFISH SURVEY OF C A S T L E M A I N E
HARBOUR (CWOMANE).
Fisheries Division
DUBLIN
1973.
OF C AdTLLTl4INE
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THE ITRTER PART 03' I)LI!TGLE BAY
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Castlemaine H a r b ~ uhas
~ t h e o l d e s t mv.ssel f i s h e s y i n I r e l a n d and
the only m~xsselp x ~ i f i c a t i o ntank t o date ( c a p a c i t y 360 tons per month
b u i l t i n 1941) i s operated i n t h a t arca,
The monthly landings and
t h e i r va3.ues s i n c e 1966 a r e given i n Table 1, Recently Castlemaine
Harbour has shown a sustallled a n n ~ ~ grow
al
L?.I
i n mussel landings,
In
September 1972 a survey was c a r r i e d out i n Castlemains Harbour arid tile
i n n e r p a r t of Dingle Bay t o estimate the 5 o t a l q u a n t i t y of a v a i l a b l e
commercial s h e l l f i s h ( s e e Fig, l ) ,
There a r e bout 6,840 acres i.n Castlemaine garbour i n s i d e a s t r a i g h t
l i n e d r w n from Inch Point t o the old Coastguard S t a t i o n a t Cromane,
About
2,000 of these a r e s u b - l i t t o r a l and t h e r e s t consisc of about 1,800 acres of
sand (which i s l e s s s u i t a b l e f o r s h e l l f i s h farming),
A fvirther 2,240 acres
of mud and sandy mud a t Barn Flyic! a r e s ~ i t a b l ef o r s h e l l f i s h c u l t i v a t i o n ,
There a r e a f u r t h e r 880 acres s u i t a b l e f o r cockle c u l t i v a t i o n outside these
b o u n d a ~ i e si n Glenbeigh S t r a i d known l o c a l l y ns t h e Cockle Strand,
RESULTS :
I n the Castlemaine Harbour i n t ~ r t l d a lzone there a r e about 1,200 tons
of mussels a t an average density of 84 tons t o the acre,
These mdssels a r e
t o be found a t s i x d i f f e r e n t locations indicated i n Fig. 1.
Table 1 gives
d e t a i l s of the approximate quantity a v n i l a l ~ l eand the area c o v e ~ e d ,the
separate and t o t a l tonnage a v a i l a b l e ,and t h e i r d e n s i t i e s ,
The length d i s t r i b u t i o n of these mussels i s shown i n Table 11 which
i n d i c a t e s t h a t a number of year c l a s s e s from 0 group u;owards a r e present i n
--
most areas, Capin na Badgear and Crow Point being t h e exception with no
juvenile mussels.
of mussels and t h a t
It w i l l be seen t h a t B a n ~Fluic has the l a r g e s t quantity
79$
of these m ~ ~ s s e lasr e below t h e acceptable commercial
length (50 mm,)
Table 111 shows t h a t i f these mussels a r e c u l l e d , the meat y i e l d of
these c u l l e d mussels over TO mm, raould Le acceptdlle,
indicatcshowever t h a t they a r e old mussels,
The s h e l l weright
2,
The sub li t t o ~ a . 1area of Cas tleinaine I-Iarbour has been dredged f o r mussels
f o r over 50 years,
I t has a v i a b l e and expanding mussel industxy,
Since
1967 over 7,000 tons of mussels were ImCed i n Cromane from the s u b l i t t o r a l
areas of Castlernaine Harbour
able
.
IV)
During these years a l s o over
7,000 tons of mlassels were transplanted fmm the i n t e r t i d a l zones t o the
deeper waters of the sv.blittora1 zones,
This i s zn indj.catioii of the
l a ~ g eq u z n t i t i e s a v a i l a b l e when proper musse2 farming metnods were ndop-ted i n
the a r e a ,
It must be assumed therefore t h a t very l a r g e q u a n t i t i e s of
s u b l i t t o r a l mussels a r e a v a i l a b l e f o r harvest+-ng, the assumption being
based on t h e f a c t t h a t t h e r e should be a t l e a s t a l o u r t o one gross r e t u ~ n
on tran,;planted mussels,
A l l length group were transplanted from the
i n t e r t i d a l zone t o the s u b l i t t o r a l zone.
The Coclcle S t r m d
ill
Glenbeigh and Banc Pluic- i n Ca~tlernaineHarbour
were a l s o surveyed f o r cockles,
L
Banc F1uic had 26 coclcles per m
The percentage meat yLeld Faas
.
The average nunher Der kilogram was 45,
14% and the length group d i s t r i b u t i o n shows t h 2 t
707: of cockles were over 4 years and t h a t year cla.sses fro111 0 upwards were
present ( s e e Tzbles V I and VII) ,
The Cockle S t r a d i n Glenbeigh had 59 cockles per m
L:
.
The average
number per kilogram wzs 59 and the average meat y i e l d was 15% The age group
d i s t r i b u t i o n i n d i c a t e s t h a t a l l t h e year c l a s s e s up t o 4 years werz present,
The length d i s t r i b u t i o n s of these cockles show t h z t 45% were over 30 mm
(see t a b l e s V, V I and VII),
C OBC LUSI ONS :
This survey has revealed t h a t the i n t e r t i d a l areas have some 1,200 tons of
mussels a t a density of 84 tons per acre f i t f o r tra:lsplanting,
a r e a has very large q u L m t i t i e s of transplanted musseZs,
The s u b l i t t o r a l
It i s d i f f i c u l t to
es tirnste t h e quanti% but they : u s t bo i n excess of 8,OCO tons,
Tlio cockles a r e sccrce but tiie j u l i - k ; '
Banc P l u i c hnd approzcbately
f o r f i s h i n g cocldes,
i s good and each aciw a t Glcnb'3igh and
4 -1;ons or coccl-lcs,
Tliere i s no l e g z l s i z e l i m i t
I n sone l o c a t i o n s in England the l e g a l s i z e is
.
*
2'(18 m).
There miglit wcl.1 be a p o t e n t . ~ a lf o r mechmical dredging of cockles i n t h i s
area(average landed p r i c e i n England and l i ~ l e si s c n C33 per ton) (Franklin 1972)
SRUrnF;
The I n t e r t i d a l a r e a i n Castiemaine H3r1~ourand tho i n n e r p a r t of bngle
1
-a
B2y have l a r g e q u a n t i t i e s of inussafs arid cockles,
2o
The subli-btoral areas of Cnstlemaine Harbour have been transplanted with
m u s s ~ l seach year from 1967 t o 1972 inclusive.
3.
The annual landings of' ~nussalszre increzsing,
4
To s u s t a i n the growth of t h e mussel f i s h e r y b i o l o g i c a l records m ~ ~ be
s t
u
kept of a l l f u t u r e s p a t f a l l s ,
5
o
11Iussels m u s t be trsmsplanted i z i f u t u r e years based on stocks of one and
two years of age,
Reference.
Frnnltlin A (1gr[2), The CockJe and i t s Fisherges,
!
Table
I n t e r t t d a l "Ydinsscls in Croinme
Table
- herage
percentage Neat, S h l l and L o s s o f
I'Iarketable Iri'i~sselstogether with average No. per Kg,
Lo cation
:
?Neat
79
I
Shell
Bane Fluic
(Wet ~ a n k )
I
I
Droicesd 1arai:m 1
( I r o n Bridge)
Capfn Bsdger
( l h d g e r j s cay)
16.0
[
4504
,
I
15.6
45.4
j
52
Loss
1
I
I
Lverage n~xiber
Per Kg.
-
Table IV
Landings 3f M u s s e l s a t Cromane e x p r e s s e d i n
T ~ n sand t h e i r v a l u e , f o r e a c h month and the t o t a l w e i g h t
and t h e i r v a l u e for each y e a r s i n c e J a n u a r y 1966.
Table V
- Asrerage nunbar
of Cockles ( a ) per square n e t r e ,
-
( b ) p e r kg. together with avercge perceztbge x e a t y i e l d .
5: 5~$,.i ,
Location
Average No, p e r
t
Banc F l u i c
1
26.0
Gle~ibeig11Strand
1I
46,O
Table V I
- Age
Average percentage
meat y i e l d
Average Bo.
p e r Kg.
d i s t r i b u t i o n of Cockles expressed i n p e r c e n t a g e ~ ~
Location
Banc F l u i c
Glenbeigh Strand
Table V I I
- Length
D i s t r i b u t i o n o f cockles i n 5nn i n t e r v a l s
expressed i n percentages.
Location
Banc F l u i c
Glenbeigh Strand
I
5 Crow Point.
6 CockEe Strand.