Department of Agriculture and Fisheries for Scotland ~engthl weight Relationships for 88 Species of Fish Encountered in the North East Atlantic K A Coull A S Jermyn A W Newton G I Henderson and W B Hall Scottish Fisheries Research Report Number 43 1989 ISSN 0308 8022
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Department of Agriculture and Fisheries for Scotland
~ength l weight Relationships for 88 Species of Fish Encountered in the North East Atlantic
K A Coull A S Jermyn A W Newton G I Henderson and W B Hall
Scottish Fisheries Research Report Number 43 1989 ISSN 0308 8022
Lengthmeight Relationships for 88 Species of Fish Encountered in the North East Atlantic
by
K A Coull, A S Jermyn, A W Newton, G I Henderson and W B Hall
Marine Laboratory, Aberdeen
Introduction As a necessary adjunct to monitoring fish stocks the Marine Laboratory has obtained a large volume of lengthlweight data for al l species of major commercial importance to Scottish fishermen. In addition a limited amount of information has also been obtained on a variety of minor species. This paper summarises the data currently available.
Material Material was collected from the middle and northern North Sea, the west coast of Scotland, Rockall and, to a lesser extent, Faeroese and Icelandic waters.
Information has been obtained from four separate sources:
a. Samples were collected during research vessel surveys. Prior to 1981 fish were deep frozen a t sea, transported back to the Laboratory and measured and weighed after defrosting. Since 1981 fish have been weighed a t sea using a Mettler PC8000 electronic balance linked to a micro-computer (Newton, 1982).
b. Samples were obtained while monitoring discards aboard commercial fishing vessels (Jermyn and Hall, 1978). These samples were kept on ice until they could be processed in the Laboratory, usual1 y three or four days after capture.
c. Rare fish records dating back to 1900 were used to provide information on species not encountered on a regular basis. It is not possible to estimate how long after death these specimens were weighed or, for the earlier part of the century, how they were preserved prior to weighing. Later specimens were preserved on ice.
d. The bulk of the data for the most common commercial species were obtained from samples purchased a t local markets. These fish had been caught 1 - 10 days before weighing, and had been kept on ice until processed.
Methods The lengths of most species were determined by measuring the distance from the tip of the snout to the extreme tip of the caudal fin. However, for skates and rays the term length refers to the distance from wing tip to wing tip. Prior to 1967 measurements were recorded to the nearest centimetre, but from January 1967 measurements have been made to the centimetre below. In order to standardise measurements 0.5 cm was deducted from the length of fish measured prior to 1967.
The total ungutted weight of each fish was recorded in grammes and for many species the gutted weight was also obtained.
Programs provided by the Laboratory's Computing and Statistics Section were used in data preparation and analysis. Where length (L), total weight (MI) and gutted weight (GW) were recorded, relationships and plots have been produced for lengthltotal weight, lengthlgutted weight and total weightlgutted weight. In the case of species for which there were no gutted weight data, only a lengthltotal weight relationship was calculated. For relationship between length and weight (total or gutted) a function of the form:
was fitted to the data, where W = weight (g) and L = length (cm).
For a relationship between total weight and gutted weight a function of the form:
was fitted to the data, where TW = total weight and GW = gutted weight.
Results The weight a t length of many species is known to vary seasonally, and wherever possible lengthlweight relationships have been prepared for each calendar month. A desirable secondary division is into the relevant sampling areas (see Appendix I, Figs 1-4) so as to make allowance for any regional variation in growth rates. Monthlylarea relationships are available only for herring (Clupea harengus (L.) 1, mackerel (Scomber scombrus (L.)), Raitt 's sandeel (Ammodytes maximus Raitt 1 934) and sprat (Sprattus sprattus (L.)) (Tables I, I I and I I I). For the main demersal species, viz cod (Gadus morhua ( L.) I,, haddock (Melanogrammus aeglefinus ( L.) 1, whiting (Merlangius merlangus ( L.) 1, sai t he (Pollachius virens ( L.) ) , lemon sole (Microstomus kik (Walbaum)) and plaice (Pleuronectes platessa (L.)), data from all areas were combined to give a monthly relationship (Table IV). Quarterly relationships are provided for spurdogs (Sgualus acanthias (L.)) (Table V) whilst for porbeagles (Lamna nasus (Bonnaterre)) an annual relationship for each sex is provided (Table VI). For all other species the available data were sufficient to provide only an annual relationship.
Plots for species where relationships are available for lengthltotal weight, lengthlgutted weight and total weightlgutted weight are shown in Appendix I I, Figures 5 to 43. Plots for species for which there are only sufficient data for a lengthltotal weight relationship are shown in Appendix I I - Figures 44 to 81. All the plots are accompanied by a table indicating the source area and number of observations. For the majority of species the source area is based on demersal market sampling areas (Fig. 1 and Appendix I) which, in turn, are associated with biological andlor geographical boundaries.
An index of species, cross-referenced by common and scientific names, is provided in Appendix 1 1 1.
Table I Herring (Clupea harengus) - total weightllength relationship
Annual value for 'b', monthly and annual mean values for 'a' are given below
Area North Rona Hebrides NW Ireland North and all North and South M inch
Sea Minch
Area Code 2,3,4,5, 1 7,9 8 6,11,12
'b' Value 3.0904 2.9776 3.0083 3.0256
'a' Values
Jan Feb Mar A P ~ May Jun Jul AwJ S ~ P oct Nov Dec
Mean Annual Values 0.00603 0.00863 0.00791 0.00742
Irish Sea and
Clyde
See Figure 4 for herring sampling areas and Appendix I for area codes.
Table II Total weightllength relationships
Annual values for 'b', monthly values for 'a' and annual mean values for 'a' are given below for mackerel (Scomber scombrus) and Raitt's sandeel (Ammodytes marinus) by sampling area
Species Mackerel Raitt's sandeel
Areas Clyde Others Shetland West Coast
Area Code 11 - -
'b' Value 3.21 3.29 3.32 3.32
'a' Values
Jan Feb Mar A P ~ May Jun Jul Aug S ~ P Oct Nov Dec
Mean Annual Values 0.0038 10 0.003001 0.001243 0.001317
See Figure 2 for mackerel sampling areas and Appendix I for area codes.
Table Ill Sprat (Sprattus spratms) - total weightllength relationship
TW = a ~ ~
Annual values for 'b', monthly and annual mean values for 'a' are given below
Area North Sea areas West Scotland Clyde
Area Code 1,2,3,4 5 6
'b' Value 3.4746 3.4746 3.4788
'a' Values
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean Annual Values "'
1
See Figure 3 for sprat bhlpling areas and Appendix I for area codes.
Table IV I, ;, Gutted weighthernth nlationlript
G W = ~ L ~ ( T W = G W x R F I
Annual values for 'b',mnt###atueD for 'a' and annual mean values for 'a' are given below each species. Raising factors (RF) for converting gutted weight t o total weight are also given
Cod Haddock
'b' Value 2.8571' 28268
'a' Values
Jan Feb Mar A P ~ May Jun Jul Aug S ~ P Oct Nov Dec
Male lW(kg) = O.OOl'922 L ~ . ~ ~ Male GW(kg) = 0.0001 14 ~ 2 . ~ ~ ~
Female TW(kg) = 0.000315 L ~ - ~ ~ ~ Female GW(kg) = 0.000047 L ~ . ~ ~ ~
Acknowledgemcmnts Our thanks are due to many members, both past and present, of the Laboratory's staff for their efforts in collecting the samples on which this paper is based. Our thanks are also due to D.C. Emslie for his advice on analysis and presentation.
References Jsrmyn, AS. and Hall, W.B. 1978. Sampling procedures for estimating haddock and whiting discards in the North Sea by Scottish fishing vessels in 1976 and 1977. ICES CM 1978/0:9.
Shanks, A.M. 1981. Further analysis of total weightllength data for spur dogfish. DAFS Marine Laboratory lnternal Report.
Shanks, A.M. 1988. Whole weightllength and gutted weightllength relationships for porbeagles. DAFS Marine Laboratory Internal Report.
Appendix I. Sampling Areas and Codes (Figs 14)
North Sea
01 Shetland 02 Viking 03 Moray Firth 04 Buchan 05 Forties 06 Central 07 Danish Coast 08 Humber 09 West Orkney 10 German Bight 11 Thames 12 IJmuiden 13 Utsire
Mackerel
01 Northwest North Sea (N) 02 Northeast North Sea (N) 03 Northwest North Sea (S) 04 Northeast North Sea (S) 05 West Central 06 East Central 07 Outer Hebrides 08 Cape Butt 09 Northwest lreland 10 Minch 11 Clyde
DEMERSAL SPECIES
West Coast of Scotland North Coast
Solan 09 West Orkney Rising Ground 40 Solan Butt of Lewis Inner Hebrides Outer Hebrides South Minch Clyde Northern lreland lrish Sea
PELAGIC SPECIES
Herring
01 Hebrides 02 North Rona 03 West Shetland 04 East Shetland 05 Moray Firth 06 Northeast North Sea 07 Northwest lreland 08 North Minch 09 South Minch 10 Clyde 11 South Buchan 12 Central North Sea 13 lrish Sea
Sprat
01 Shetland 02 Moray Firth 03 East Scotland ,04 Northeast England 05 West Scotland 06 Clyde 07 Northern lreland 08 Northern North Sea 09 Central North Sea 10 Northwest Scotland
Figure 1. Demersal Market Sampling Areas
Figure 2. Mackerel Sampling Areas
Figure 3. Sprat Sampling Areas
Figure 4. Herring Sampling Areas
1 O W 8W 6 W 4W 2W 0 2E 4E 6E
Appendix I I . Figures 5-81 showing relationships between length, total weight, and gutted weight for various species
Figure 5 . Cuckoo Ray - Raja naevus Mul,ler & Henle
Length Ccm)
0 500 1000 1500 2000
Gutted Weight Cg)
8 16 24 32 40
Length C c m l
Areas collected : Shetland
Buchan
Butt of Lewis
Data source : Discard trips
Date collected : 1981 - 1984 How measured : cm below Cwingspsn)
Annual Relationship
L/TW L/GW GW/TW
obs used 173 173 173
min L 8 8 - max L 30 30 - min TW 19 - 19
max TW 1974 - 1974
min GW - 17 17
max GW 1832 1832
Figure 6 . Blue Skate - RaJa batis Linnaeus
20 30 40
Length Ccml Length Ccml
Are- collected : Inner Hebrides
Morw Fir th
South Hi nch
Data swrce : Diecard tripe
Date collected : 1982 - 1985 cm below How measured :
obs used
min L
max L
min TW
max TW
min GW
max GW
Relationship
L/GW GW/TW
e e ie - 49 - - 88
- 1686
79 79
1713 1713
Gutted Weight Cg)
Figure 7. Spotted Ray - Raja montagui Fowler
Length Ccml Length (cml
0 500 1000 1500 2000
Gutted Weight (gl
Areas col lected : Shetland
North Coast
West Coast
of Scotland
Data source : Research vessels
Discard t r i p s
Date collected : 1977 - 1985 How measured : cm below
Annua l
L/TW
obs used 87
min L 12
max L 42
rnin TW 27
max TW 1890
rnin GW - rnax GW
Relationship
L/GW GW/TW
87 87
12 - 42 - - 27
- 1890
25 25
1794 1794
Figure 8. Starry Ray - Raja radiata Donovan
8 16 24 32 40
Length Ccrnl
9 15 21 27 33
Length (cml
Areas collected : North Sea
Data source : Discard t r i p s
Data collected : 1977 - 1984 HOW measured : cm below
obs used
min L
max L
rnin TW
max TW
rnin GW
max GW
Annual Relationship
L/TW L/GW GW/TW
376 85 85
9 9 -
33 31 -
27 - 27
1160 - 745
- 24 24
- 766 766
Gutted Weight (91
Figure 9. Thornback Ray - Raja clavata Linnaeus
24.5 27.0 29.5
Length Ccml Length Ccml
How measured :
Areas collected : Shetland
Moray Fir th
Buchan
South Min*,,)i % L -..
Data source : Discard ripe
Date collected : 1981 - 1 84
Annua l
L/TW
obs used 12
min L 22
max L 31
min TW 197
max TW 572
min GW - max GW
Gutted Weight Cgl
Figure 10. St ing Ray - Dasyatis pastinaca Linnaeus
20 24 28 32 23.5 25.0 26.5 28.0 29.5
Length Ccml Length tcml
Areas collected : Moray Firth
Buchan
Butt of Lewis
Data source : Rare fish records
Date col lected : 1960 - 1965
9.' How measured :
/ Annua l
L/TW
obs used 5
min L 16.5
max L 28.5
min TW 131
mex TW 790
300 I I I I min GW - 300 400 500 600 700 max GW
cm below Cwingspanl
Relationship
L/GW GW/TW
4 4
23.5 - 28.5 - - 350
- 790
319 319
696 696
Gutted Weight Cgl
Figure 11. Eagle Ray - Myl iobatis aqui la Linnaeus
Length Ccml Length Ccml
Areas collected : Buchan
Data source : Rare f i sh records
Date collected : 1957 - 1970
How measured : cm below
Annual Relationship
L/TW L/GW GW/TW .'
obs used 12 3 3
min L 27.5 27.5 - max L 58.5 51.5 - min TW 612 - 612 7
max TW 3690 - 2054
min GW - 554 554
max GW
Gutted Weight Cgl
I' F igure 12. Sea Lamprey - Petromyzon mar i nus L innaeus I
40 60 80
Length Ccm)
0 300 600 900 1200
Gutted Weight Cgl
45 60 75
Length Ccm)
Areas collected : North Sea
Clyde
Faroe
Data source : Rare fish records
Date collected : 1953 - 1973 How measured : cm below
Annua I
L/TW
obs used 25
min L 31.5
max L 93
min TW 41
max TW 1310
min GW - mex GW
Relationship
L/GW GW/TW
13 13
31.5 - 84.5 - - 41
- 1169
34 34
1113 1113
Figure 13. Three-bearded Rockl ing - Gaidropsarus v u l g a r i s Cloquet
Length Ccml
32 36 40
Length Ccml
Areas collected : Shetland
Buchan
West Coast of
Scot l and
Data source : Rare fish records
Research vessels
Date collected : 1952 - 1985 How measured : cm below
Annua l Re l at i onsh i p
L/TW L/GW GW/TW
obs used 17 I1 11
min L 29.5 29.5 - max L 47 43.5 - min TW 230 - 230
max TW 972 - 764
min GW - 210 210
max GW 726 726
Gutted Weight Cgl
Figure 14. Tadpole F i s h - Raniceps raninus (Linnaeusl
Length Ccml
TW = GW * 1.0845
o ! I I I I
15 20 25 30 35
Length Ccml
Areas collected : North Sea
West Coast
of Scotland
Data source : Rare fish records
Date collected : 1954 - 1982 How measured : crn below
Annual Relationship
L/TW L/GW GW/TW
obs used 21 10 10
min L 13.5 15.5 - max L 30.5 30.5 - min TW 24 - 47
Rabbitfish Raitt's sandeel Raja batis Raja clavata Raja montagui Raja naevus Raja radiata Raniceps raninus Ray's bream R e d band-fish Red gurnard Red mullet Red sea bream Rhinonemus cimbrius
Saithe Sarda sarda Scomber scombrus Scomberesox saurus Scophthalmus maximus Scophthalmus rhombus Sea lamprey Sebastes viviparus Skipper Snake blenny Solea solea Solenette Spondyliosoma cantharus Spotted dragonet Spotted ray Sprat 1 1 1 Sprattus sprattus 111 Spurdog V Squalus acanthias V Sguatina sguatina Starry ray Sting ray Sturgeon Sunfish Syngnathus acus
Tadpole fish Thickback sole Thornback ray Three-bearded rockiing Thunnus thynnus Topknot Torpedo nobiliana Trachinus draco Trachipterus arcticus Trachurus trachurus Trigger-f ish Trigla lucerna Trisopterus luscus Trisopterus minutus Tub gurnard Turbot Twaite shad
Viviparous blenny
Whiting Witch Wreckfish
Zeugopterus punctatus Zeus faber Zoarces viviparus
Table Figure
Printed by HMSO Reprographic Unit, Edinburgh 7/89 750 (025212)