COMPARATIVE STUDY OF BIOMETRIC CHARACTERS OF THE “GOLDEN” COD AND A SAMPLE OF COD OF TYPICAL PIGMENTATION (GADUS MORHUA MORHUA L.) CAPTURED IN THE SVÅLBARD BANK

Beata Więcaszek¹, Jolanta Antoszek², Artur Antoszek^1
1 Department of Fish Systematics, West Pomeranian University of Technology, Szczecin, Poland
² Department of Immunology, Microbiology and Physiological Chemistry, West Pomeranian University of Technology, Szczecin, Poland

ABSTRACT

A single specimen of the northeast Atlantic cod Gadus morhua morhua L., of unusual golden tint, was captured in the eastern part of Svålbard Bank area. At the same time, a sample of 50 individuals of typical colouration was collected from the same area. The main objectives of this study were to present a detailed morphometric characteristics of golden specimen as well to compare data obtained with the morphometrics of the sample of typically pigmented cod collected from this fishing ground. The morphometric characteristics involved metric characters of the body and head, meristic features as well as metric characters of cod neurocranium. In addition examination of the stomach contents, condition of cod and the one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) for separating myofibrillar proteins by molecular weight were performed in the whole sample as well. Morphometric analysis revealed some differences between "gold" morphotype and typically coloured specimens of Atlantic cod from the same location of sampling. Moreover, differences in the diet composition were found as well. No differences were found in the comparative electrophoretic study in the composition of myofibrillar proteins in white muscles. Meristic characters of cod studied can be presented by the following formula: D₁ 13-15, D₂ 17-22, D₃ 16-21, D 47-58, A₁ 17-23, A₂ 16-20, A 35-43, P 18-25, C 54-58, V 6, r.br.7, vt. 49-53, vt_c 30-34, vt_a 18-20, sp.br._1I 22-27, sp.br._1II 17-19, sp.br._2I 16-20, sp.br _2II 14-17. Values of the meristic characters of the golden specimen were fit within the ranges obtained. The mean value of condition factor K amounted to 1.01 in the sample of typically coloured cod, whereas for golden cod 1.07. 

Key words: golden cod, Gadus morhua, metric characters, meristics, neurocranium, electrophoresis, diet, condition factor.

INTRODUCTION

Adult Atlantic cod G. morhua are typically countershaded with a dark back gradating to a light underbelly. Fish dorsal and lateral surfaces are overlaid by numerous, rounded brown spots [15]. A single specimen of the Northeast Atlantic cod Gadus morhua morhua L., of the unique golden colouration, was captured in the eastern part of Svalbård Bank area. There is no records in the literature available on a golden spotless cod. The golden individual from the Svålbard Bank varies markedly in the type of colouration when compared to the "golden cod of Labrador" described in the literature [7,21].

The literature on morphometrics, especially concerned the cod neurocranium, on Atlantic cod is very scarce, whereas on cod from Svalbård Bank area is practically not available. The main objectives of this study were to present a detailed morphometric characteristics of the unique cod having a golden colouration as well as to compare data obtained with the morphometrics of the sample of typically coloured cod collected from this ground. The morphometric characteristics involved metric characters of the body and head, meristic features as well as metric characters of cod neurocranium.

In addition examination of the stomach contents, condition of cod and the one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) for separating the white muscles myofibrillar proteins by weight were performed as well.

MATERIAL AND METHODS

Morphometric analysis
A single specimen of Atlantic cod Gadus morhua morhua L., of unique colouration, was captured in the eastern part of Svålbard Bank, during the commercial cod catch on 12 October, 2004 (Fig. 1). The depth of trawling (bottom trawl-set "Bacalao") ranged within 300-400 m. It was a female 63.0 cm of total length, 57.5 cm of SL and weight of 2030 g, in the age of 6+. The general body tint of the cod examined was bright golden yellow above, fading to white on the belly and lower jaw, with golden head. All fins were lemon yellow. At the base of pectoral fins was a black spot. Eyes were fully pigmented.

At the same time a sample of 50 fishes (33.5-63.4 cm of TL) of typical colouration was collected from the same site. This sample was investigated in order to obtain a comparative material due to the assumption that the golden specimen, except the specific skin tint, differed in other body characters as well.

When considered the allometric pattern of growth in cod, the sample of 50 individuals was divided into 3 length classes: 33.5-43.4 cm (n = 15), 43.5-53.4 cm (n = 17) and 53.5-63.4 cm (n = 18). The golden individual was allocated to the last length class 53.5-63.4 cm. Thus the detailed examinations of morphometric characters of the body and head were made on a sample of 18 individuals of TL ranged within 53.5-63.4 cm, and separately on the golden individual.

Methods for determining morphometric characters followed Więcaszek [20], with some modifications (Fig. 2). Measurements were taken with an aid of electronic caliper and under the electronic microscope Nikon SMZ 1000, with the Lucia Measurement System, with accuracy of 1 mm. Counts and measurements were made on the left side of specimens. Subunits of the head are presented as proportions of head length HL. Head length and measurements of body parts are given as proportions of standard length SL. Morphometric characters and their symbols, as well as results of the study are presented in Tables 3 and 4. We followed Holčik [8] and Leviton et al. [12] for institutional abbreviations, with some modifications.

A total of 37 morphometric characters were examined. The following metric characters were studied: total and standard lengths (TL, SL), head and interorbital lengths (HL, io), head width (lac), preorbital and postorbital lengths (prO, poO), horizontal and vertical eye diameters (Oh, Ov), length of upper and lower jaws (lmx, lmd), barbel length (lb), predorsal and preanal lengths (pD₁, pA₁); length and height of three dorsal fins (lD_1bs, lD_2bs, lD_{3 bs}, hD₁ , hD₂, hD₃) , as well as distances between them (D₁-D₂, D₂-D₃), length and height of two anal fins (lA_{1 bs}, lA_{2 bs}, hA₁, hA₂), as well as distance between them (A₁-A₂); pelvic and pectoral fin lengths and their base length (lV, lP, lV_bs, lP_bs); distances between pectoral and pelvic fin (P-V) and pelvic and anal fins (V-A₁); length of swim-bladder and caudal peduncle (lsb, lpc); maximum and minimum body height (H, h).

The measurements of neurocranium were made on cod individuals allocated to the 53.5-63.4 cm length class. A total of 19 (with one of golden specimen) skulls were examined.

The following metric characters were studied: the total cranial length l. cr (= v-boc), the distances: from the mesethmoid to the supraoccipital bones meth-soc, from the vomer to the basiooccipital bone v-boc, the width of following bones: the vomer lav, the lateral ethmoid bone laeth.l, the frontal bone (in the notch) laf ₁, the frontal bone (in the broadest region) laf ₂, the sphenotic bone laspho, the pterotic bone lapto, and the depth of following bones: mesethmoid hmeth, lateral ethmoid heth.l, sphenotic hspho, supraoccipital – in the notch hsoc₁ and in the posterior part hsoc₂. The measurements [17, 18, markedly modified] were taken with an aid of electronic caliper, to the nearest 0.1 mm (Fig. 3). All cranial characters were expressed as per cent neurocranium length l.cr.

In addition, the following ratios of neurocranium characters were calculated: the lateral ethmoid bone depth to lateral ethmoid bone width heth.l/laeth.l, the depth of supraoccipital bone tothe pterotic width hsoc₂/lapto and sphenotic bone depth to the sphenotic width hspho/laspho. Characters studied of neurocranium and their symbols are presented in Table 1.

The following meristic characters were studied in the whole sample – 50+1 specimens of cod: number of rays in three dorsal fins D₁,D₂,D₃, total amount of rays in dorsal fins D, number of rays in two anal fins A₁, A₂, total amount of rays in anal fins A, ray count in pelvic, ventral and caudal fins P, V, C, respectively (all fins are supported by soft rays), branchiostegal ray count r.br., as well as vertebral count vt. Abdominal vt_a  and caudal vt_c vertebrae were tabulated separately. Gill rakers were counted on the first and second branchial arches, in two rows (sp.br._{1 I} sp.br._{1 II}, sp.br._{2 I ,} sp.br._{2 II} , respectively). Meristic characters and their symbols, as well as results of the study are presented in Table 4.

All data were subjected to statistical treatment involving standard deviation (SD), mean (M) and coefficient of variation (CV). According to Ruszczyc [16], the coefficient of variation is statistically significant when equals or exceeds 8%.

Electrophoretic study
In order to check the hypothesis of lack of differences in biochemical structure of cod skeletal muscles between the golden cod and a sample of individuals of typical colouration, the one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) for separating proteins by weight was performed through a 12% SDS [9,11]. The measurements of total protein content in the supernatant was performed according to Bradford method [14].

Gels were stained with Coomassie Briliant Blue R-250 (Sigma). Six protein markers were used (Table 2).

The Wide Range Sigma Marker ^TM was used to determine the molecular weight of protein fractions. The unit of molecular weight was kilodalton (kDa).

Electrophoregrams were analyzed by the program Gel Scan ver. 6.1 and Digimizer 3.04. The study was performed on all cod specimens (50+1 the golden individual).

Study of stomach contents and condition of fish
As the golden individual was allocated into the length class 53.5-63.4 cm, the detailed examinations of stomach contents were performed on a sample of 18 individuals of TL ranged within 53.5-63.4 cm, and separately on the golden individual. The food items were determined and weighed to the nearest 0.01 g for each individual of cod examined. Next the summarized weight of particular food items were calculated as percentage contribution to the total weight of all stomachs contents [19] – separately for the golden cod and a sample of 18 typically coloured cod.

The fish condition was assessed with the widely applied Fulton formula:

K = W/L³ x 100, where K is coefficient of condition, W – total weight of fish (g), L – standard length SL (cm).

RESULTS

Morphometrics of golden cod and the sample of typical colouration
Results of morphometric analysis of fish body are presented in Tables 3 and 4.

Analysis of the coefficient of variation (Table 3) showed the CV  to be high (showing a high variability) with respect to eight characters: hc – head depth, hD₂ – height of D₂, D₁–D₂ distance, IV_bs– length of V base, lpc – length of caudal peduncle, h – minimum height, D₂–D₃ and A₁–A₂ distances (from 11.25 to 16.62 % of CV, respectively). The lowest variability showed: pA – preanal length, TL – total length, lA₁ – length of A₁ base, V–A distance, lsb – length of swim-bladder, P–V distance and IP – length of pectoral fin (from 1.36 to 4.89% of CV, respectively). When compared the values of morphometric characters related to the body length SL of the golden cod and the sample of cod of typical colouration collected in the same sampling site, values of most (67.86%) morphometric characters were fit within the ranges obtained, except: the four distances: pA₁, P–V, V–A, D₁–D₂, next the height of D₃ and of A₁, length of P, length of A_2bs and length of lsb. In case of height of D_3, preanal pA₁, P–V and D₁–D₂ distances, the difference were very small  whereas in case of remaining characters the differences were bigger. D₁–D₂ distance was a very variable character, the height of D₃ was a medium variable one (therefore not very valuable in the taxonomic evaluation), however the length of fin A₂, preanal length pA, length of fin P and V–A₁ distance were considered as stable ones.  The golden individual had a distinctly shorter base of anal fin lA₂, shorter fin P but longer V–A₁ distance when compared to sample of typical colouration.

Analysis of the coefficient of variability of morphometric characters pertinent to head of golden cod and the sample of cod of typical colouration, related to HL (Table 4), showed the CV to be high with respect to four characters, namely the most variable Ov – vertical eye diameter (CV 11.17%), next Oh – horizontal eye diameter relatively highly variable, too (CV 9.07%), io – interocular distance (8.79%) and lb – barbel length (8.29%). The lowest variability showed: lower jaw lmd and upper jaw lmx lengths (CV 1.11 and 3.06%, respectively) as well as preorbital prO  distance (3.58%).

When compared the values of morphometric characters of fish head related to the head length HL of the golden cod and the sample of cod of normal colouration collected in the same sampling site, values of 50.0% of morphometric characters number were fit within the ranges obtained. The golden cod had longer interorbital distance io, smaller vertical eye diameter Ov, shorter barbel (lb) and slightly shorter upper jaw (lmx) and narrower head (lac).

Morphometric characters of the neurocranium of cod examined related to the total cranium length (l.cr.) showed a small variability, with the highest CV =7.86 of the sphenotic bone depth hspho (Table 5). The most stable characters found were as follows: the mesethmoid-supraoccipital bone distance meth-soc, the vomer-basiooccipital bone distance v-boc, width of pteroic bone lapto and the supraoccipital bone depth, in the posterior part hsoc₂ (CV value from 0.79 to 2.71%, respectively). The differences between the golden cod and a sample of typically coloured cod were found in 6 of 13 characters of neurocranium studied. The golden cod had narrower neurocranium in five regions: of lateral ethmoid bone laeth.l, frontal bone – both in the notch and the broadest region (laf₁,laf₂), pterotic and sphenotic bones (lapto, laspho). The biggest difference was found in the mesethmoid bone depth hmeth. In this case the neurocranium of golden cod was markedly lower in this area when compared to cod having typical colouration.

The greatest differences were found in the neurocranium shape, especially in two cross sections (Table 5): in the anterior part in the area of ethmoid lateral bone heth.l/laeth.l (the neurocranium of golden cod is higher but narrower when compared to the sample possessing typical colouration) and in the posterior part where the shape of the cross section hsoc₂/lapto is nearly quadrate in golden cod while in the sample compared is markedly higher. The third cross section, in the medium part of neurocranium is similar in both objects of study, being slightly higher in the golden cod. All characters examined are recognized as stable, with the CV value beneath 8%. The lowest variability showed the relation hsoc₂/lapto (CV = 2.91%).

Results of meristic analysis of the whole sample and golden individual are presented in Table 6. Meristic characters showed a low variability when analyzed the CV values. Vertebral counts (vt. – total count and both vt_c. vt_a – caudal and abdominal counts) appeared to be the most stable characters with CV ranged from 1.72 to 2.55%, respectively. Relatively higher variability was found in: D – total ray amount in dorsal fins and A₁-ray count in first anal fin (CV 7.08 and 7.06, respectively).

When compared the meristic characters (all fin ray counts, branchiostegal ray count, vertebral counts and count of gill rakers on two first gill arches) of the golden cod and the sample of cod of normal pigmentation collected in the same sampling site, values of the characters were fit within the ranges obtained.

Electrophoretic study
The comparative electrophoretic study revealed no differences in the composition of myofibrillar proteins in white muscles between the golden specimen and a sample of typically coloured cod from Svålbard Bank area (Fig. 4). When compared fraction molecular weight  of the golden cod and the sample of cod of normal pigmentation collected in the same sampling site, values of the characters were fit within the ranges obtained (Table 7).

Study of stomach contents and condition of fish
Results of examination of stomach contents and condition of fish are summarized in Table 8.

In the stomach of golden cod only two specimens of northern shrimp Pandalus borealis, partially digested were found. The weight of stomach contents was 12.05 g. The colour of contents was dark-red and gray.

In stomachs of cod having typical colouration in the length class of 53.4-63.3 cm, fish (herring and haddock) prevailed, contributing to 99.86% of total stomach weight. The contribution of shrimp Pandalus borealis (Crustacea) in the total weight of fish stomachs was very low.

The condition factor K of golden individual amounted to 1.07. In the sample of cod having the typical pigmentation, the condition factor covered the range from 0.80 to 1.16, with the average of 1.01.

DISCUSSION

There is no records noted in the literature available on a golden spotless cod. According to Bigelow and Schroeder [2], occasionally one sees a spotless cod, but these are unusual. Any spots were detected on the skin of specimen from the Svålbard Bank area, despite of the dark blotch at the base of pectoral fin.

The golden individual from the Svålbard Bank varies also markedly in the type of golden colour when compared to the "golden cod of Labrador", which have golden-brown colouration, with brown spots on the sides likely the result of an invertebrate diet rich in carotenoids [7,21].

In general yellow, orange and golden colours in fish skin are produced by a type of chromatophore known as a xanthophore. These pigmented cells owe their colouration to the presence of carotenoid, which is not synthesized by animals but is obtained from plants and/or phytoplankton through the food chain [3].  A diet rich in carotenoids results in enhanced red, orange and yellow pigments in fish.  The red colour of Norwegian coastal cod was attributed by Fox and Vevers [5] to a supply of carotenoids from its diet of predominantly shore crab (Carcinus maenas). Similarly, "golden cod of Labrador" feed predominantly on a diet of benthic invertebrates such as shrimps, mysids, amphipods, and various crab species [13]. "Golden cod of Labrador" fed with diet of fish over the 12-week experimental period, lost much of their brown or red pigmentation and became countershaded [7].

Our observation that the stomach of golden specimen contained digested crustaceans (Pandalus borealis) is consistent with such a carotenoid intake from phytoplankton or plant material low in the food chain. In stomachs of cod having typical colouration, fish (herring and haddock) prevailed, contributing to 99.86% of total stomach weight, while the contribution of shrimp Pandalus borealis in the total weight of fish stomachs was very low. Northwestern Atlantic cod, inhabiting deep (>100 m) continental shelf waters off Newfoundland and Labrador preferentially feed on fish (capelin Mallotus villosus) when available in abundance [7]. The sample studied including the golden cod  was captured at the depth of 300-400 m; therefore the fish found in stomachs of cod having typical pigmentation were a typical diet component, whereas contents of golden cod stomach – exclusively crustaceans in the fish of 63 cm of total length TL was thus uncommon. However in the Barents Sea cod predation is considered to be one of the most important factors influencing shrimp Pandalus borealis population dynamics; fish at age 3–6 (30–60 cm) had the maximum influence on shrimp stocks, especially during spring-summer [1]. The period of capture of the cod sample studied was different (October) influencing evidently the diet of cod having typical pigmentation.

Analysis of metric characters of the sample of cod examined revealed some differences between differently coloured fish. The most differences were found in the head and neurocranium structure. The golden individual had narrower neurocranium in five regions and the neurocranium was markedly lower in the area of the mesethmoid bone, when compared to cod having typical colouration. In addition, the greatest differences were found in the shape of neurocranium cross sections: in the area of anterior part of ethmoid lateral bone and in the area of posterior part. According to Jørgensen at al. [10], the skull bones are expected to reflect differences in feeding which was recorded and documented in the case of herring Clupea harengus from the Baltic Sea.

However not only a supply of carotenoids but the high plasmatic levels of MSH, and perhaps other hormones, can also enhance xanthic colouration by dispersing carotenoid intracellularly within the xanthophores. Melanocyte-stimulating hormone belongs to a group called the melanocortins. This group includes ACTH, alpha-MSH, beta-MSH and gamma-MSH. These peptides are all cleavage products of a large precursor peptide called pro-opiomelanocortin (POMC). Alpha-MSH is the most important melanocortin for pigmentation [3,4].

Reports of unique golden colouration were found only in the case of the closest related species, namely haddock Melanogrammus aeglefinus. According to Bigelow and Schroeder [2] occasionally a haddock may be decidedly golden on the back and sides, with the lateral line golden, and such fish may lack the dark blotches. A golden specimen of haddock was caught in a trawl off the Scilly Isles, in August 1997. The research worker of National Aquarium (Plymouth) explained that this was an albino freak specimen of the Melanogrammus aeglefinus and it was enrolled into Rare Fish Records (22).

CONCLUSIONS

The golden individual had an evidently shorter base of anal fin, shorter pectoral fin and longer distance between pectoral and first anal fins as well as a narrower head when compared to cod having typical pigmentation. Additionally, the neurocranium was narrower in five regions and lower in the area of the mesethmoid bone. The cross sections showed different proportion of the bones examined.

Meristic characters of cod studied can be presented by the following formula: D₁13-15, D₂17-22, D₃16-21, D 47-58, A₁17-23, A₂16-20, A 35-43, P 18-25, C 54-58, V6, r.br.7, vt. 49-53, vt_c 30-34, vt_a 18-20, sp.br._1I 22-27, sp.br._1II 17-19, sp.br._2I 16-20, sp.br _2II 14-17. Values of the meristic characters of the golden specimen were fit within the ranges obtained.

The comparative electrophoretic study revealed no differences in the composition of myofibrillar proteins in white muscles between the golden specimen and a sample of typically coloured cod.

The stomach contents varied between the golden individual of cod (exclusively crustaceans) and the remaining sample, where fish prevailed markedly.

The mean value of condition factor K amounted to 1.01 in the sample of cod possessing typical pigmentation and 1.07 for the golden individual.

ACKNOWLEDGMENTS

Authors would like to thank Mr W. Szaszkiewicz who provided the unique golden specimen of cod to our laboratory and to dr B.Wydrowska for help in determining the food of golden cod.

REFERENCES

1. Berenboim B.I., Dolgov A.V., Korzhev V.A., Yaragin N.A., 2000. Cod impact on the stock dynamics  of shrimp Pandalus borealis in the Barents Sea and its implication in multispecies models. J. Shell. Res. 19(1), 552.

2. Bigelow H. B., Schroeder. W. C., 1953. Fishes of the Gulf of Maine. Fish. Bull. 74. 53, 199.

3. Burton D., 1981. Physiological responses of melanophores and xanthophores of hypophysectomized and spinal winter flounder. Pseudopleuronectes americanus Walbaum. Proc. R. Soc. Lond. B 213, 217-231.

4. Burton D., 1993. The effects of background coloration and α-MSH treatment on melanophore frequency in winter flounder. Pleuronectes americanus. J. of Comp. Physiol. A. Neuroethology. Sensory. Neural and Behavioral Physiology. 173(3), 329-333.

5. Fox H.M., Vevers G., 1960. The Nature of Animal Colours. Sidgwick & Jackson, London, 246.

6. Froese R., 2007. Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations. J. Appl. Ichthyol. 22, 241-253.

7. Gosse K., Wroblewski J., 2004. Variant colorations of Atlantic cod (Gadus morhua) in Newfoundland and Labrador nearshore waters. ICES J. of Mar. Sci.: Journal du Conseil 61(5), 752-759.

8. Holčik J., 1989. The freshwaters fishes of Europe. Aula-Verlag. Wiesbaden.

9. Isani G., Andreani G., Monari M., Libera L.D., Carpene E., 2000. Biochemical changes in gilthead sea-bream white muscles during post-larval growth. Basic Appl. Myol. 10(6), 285-290.

10. Jørgensen H.B.H., Pertoldi C., Hansen M.M., Ruzzante D.E., Loeschcke V., 2008. Genetic and environmental correlates of morphological variation in a marine fish: the case of Baltic Sea herring (Clupea harengus). Can. J. Fish. Aquat. Sci. 65, 3389-400.

11. Laemmli U.K., 1970. Cleavage of structural proteins during the assembly of the head of bacteriophage. Nature 227, 680-685.

12. Leviton A.E., Gibbs Jr. R.H., Heal E., Dawson C.E., 1985. Standards in herpetology and ichthyology. Part I. Standard symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia, 802-832.

13. Morris C.J., Green J.M., 2002. Biological characteristics of a resident population of Atlantic cod (Gadus morhua) in southern Labrador. ICES J. of Mar. Sci. 59, 666-678.

14. Pollard H. B., Menard R., Brandt H.A., Pazoles C. J., Creutz, C.E., Ramu A., 1978. Application of Bradford's protein assay to adrenal gland subcellular fractions. Anal. Biochem. 86(2), 761-763.

15. Robins, C.R., Ray G.C., 1986. A field guide to Atlantic coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A, 354.

16. Ruszczyc Z., 1981. Metodyka doświadczeń zootechnicznych [Methodology of experimentations in animal husbandry]. PWRiL. Warszawa [in Polish].

17. Sobociński A., 1993. Cerebrocranial differentiation of the Arctic charr (Salvelinus alpinus) in water bodies of the Hornsund region (Spitsbergen). Acta Ichthyol. Piscat. 13 (Suppl.), 31-35.

18. Svetovidov A. N., 1948. Ryby. Treskoobraznye [Fish. Gadoids]. Izd. Akademii Nauk SSSR. Moskva – Leningrad. 9(4), 160-182 [in Russian].

19. Szypuła J., 2001. Przewodnik do ćwiczeń z biologii ryb [Manual to practice in fish biology]. Wyd. AR. Szczecin [in Polish].

20. Więcaszek B., 1988. Morphometry of southern blue whiting Micromesistius australis Norman, 1937 – from the region of Burdwood Bank. Acta Ichthyol. Piscat. 18(2), 3-18.

21. Wroblewski J., Neis. B., Gosse K., 2005. Inshore stocks of Atlantic cod are important for rebuilding the east coast fishery. Coastal Management. 33, 411-432.

22. Marine Wildlife News. http://www.glaucus.org.uk/news2.htm

Accepted for print: 24.04.2009

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.