Web of Science search on 'Pollachius' in title as of Oct. 12, 1999.
Bromley, P. J., Watson, T., and Hislop, J. R. G. (1997). Diel feeding patterns and the development of food webs in pelagic 0-group cod (Gadus morhua L.), haddock (Melanogrammus aeglefinus L.), whiting (Merlangius merlangus L.), saithe (Pollachius virens L.), and Norway pout (Trisopterus esmarkii Nilsson) in the northern North Sea. Ices Journal of Marine Science 54, 846-853.
Stomach content analysis was used to investigate feeding interactions between pelagic 0-group gadoids in the northern North Sea. The species studied were cod (Gadus morhua L.), haddock (Melanogrammus aeglefinus L.), whiting (Merlangius merlangus L.), saithe (Pollachius virens L.) and Norway pout (Trisopterus esmarkii Nilsson). The fish were caught at a site south-east of Shetland in late spring during 24 h depth- stratified fishing using a mid-water trawl. There was overlap in the range of prey consumed by the various species. Fish of 1-3 cm in length fed mainly on copepods and other invertebrates. Larger Norway pout continued to feed almost entirely on copepods, but the other species diversified as they grew to include fish in their diet, cod and whiting becoming almost entirely piscivorous. Haddock and saithe ate moderate amounts of fish combined with crustacea in roughly equal proportions. The depth at which the fish were caught did not appear to influence the range of prey consumed, but fish was slightly more prevalent in the diet of 0-groups caught near the surface. The results indicate that a food web of increasing complexity can develop during a relatively short time scale in late spring when the 0-group gadoids are pelagic. Generalised linear modelling revealed diel feeding patterns which were size-dependent and species-specific. In 2-3 cm cod, for example, peak feeding was during the period 1200-2000 h and high numbers of prey (mainly invertebrates) were consumed, The stomachs of the larger cod (3-5 cm) contained smaller numbers of mainly fish prey and peak feeding switched to 0000-0800 h. The piscivorous 0-groups were capable of eating relatively large prey items, providing the opportunity for larger individuals to eat younger or slower-growing individuals from the same year class. Whiting in particular were subject to substantial levels of cannibalism and inter-specific predation, Feeding interactions of this sort might be of sufficient magnitude to influence significantly the survival and recruitment of gadoids. High fecundity in whiting, coupled with multiple spawnings over a protracted period of time means that offspring from late spawnings could act as a food reserve for siblings from earlier spawnings. Such prey provide substantially more energy than the female invested in producing the original egg from which the prey was derived. This mechanism could prove to be an energy-efficient way of providing food reserves for the early offspring. It is also an efficient way of governing population size through density- dependent mortality. (C) 1997 International Council for the Exploration of the Sea.
Chauvet, J., Lee, W. J., Chauvet, M. T., and Acher, R. (1994). Bony Fish Neurophysins - Identification of Msel-Neurophysin and Vldv-Neurophysin of the Pollack (Pollachius-Virens). International Journal of Peptide and Protein Research 44, 130-138.
The two types of neurophysins known in vertebrate species, namely MSEL-neurophysin (vasopressin-like hormone-associated neurophysin) and VLDV-neurophysin (oxytocin-like hormone- associated neurophysin) have been purified from the pollack (Pollachius virens) pituitary through a combination of molecular sieving and high-pressure liquid chromatography (HPLC). Homogeneity has been checked by gel electrophoresis and rerun in HPLC. The apparent molecular masses measured by SDS- electrophoresis are near 12 kDa, significantly higher than those found for their mammalian homologues (10 kDa), The two types of neurophysins have been recognized through their N- terminal amino acid sequences. The primary structure of MSEL- neurophysin has been partially determined using automated Edman degradation applied on native and reduced-alkylated protein, as well as peptides derived by trypsin or staphylococcal proteinase hydrolyses. Comparison of pollack MSEL-neurophysin with ox, goose and frog counterparts reveals that particular positions in the polypeptide chain are subjected to substitutions and that the numbers of substitutions do not seem closely related to the paleontological times of divergence between the different vertebrate classes. (C) Munksgaard 1994.
Christiansen, R., and Palmork, K. H. (1996). Distribution and elimination of [C-14] in saithe (Pollachius virens L) after application of a single dose of [C-14] polyhexamethylene hydrochloridebiguanide. Bulletin of Environmental Contamination and Toxicology 56, 121-128.
de la Higuera, M., Akharbach, H., Hidalgo, M. C., Peragon, J., Lupianez, J. A., and Garcia-Gallego, M. (1999). Liver and white muscle protein turnover rates in the European eel (Anguilla anguilla): effects of dietary protein quality. Aquaculture 179, 203-216.
The influence of the quality of dietary protein source on growth and protein synthesis and degradation rates was studied in the liver and white muscle of the European eel. Fish were fed isonitrogenous diets differing in protein source: one (control) contained fish meal, three others incorporating meat meal (MM) or sunflower meal (SFM) as the only protein source, and SFM supplemented with some essential amino acids (EAAs) were also tested. Fish fed diets containing unsupplemented MM or SFM exhibited dietary utilization and growth indices poorer than those fed the control, while EAA supplementation greatly improved the performance of the SFM-diet. Liver showed higher rates of protein synthesis (k(s)) and degradation (k(d)) associated with a higher capacity for protein synthesis per unit of DNA but a lower protein deposition efficiency (PDE), compared to muscle. Low quality dietary protein increased the protein turnover rate, with a higher protein synthesis rate per unit of DNA and RNA but a decrease of PDE. In white muscle, MM and unsupplemented SFM diets decreased k(s) without changing k(d). The MM diet reduced the efficiency of protein synthesis and deposition. EAA supplementation of the SFM diet raised the protein synthesis rate and capacity as well as protein deposition compared to control values. (C) 1999 Elsevier Science B.V. All rights reserved.
Dulavik, B., Sorensen, N. K., Barstad, H., Horvli, O., and Olsen, R. L. (1998). Oxidative stability of frozen light and dark muscles of saithe (Pollachius virens L.). Journal of Food Lipids 5, 233-245.
Saithe, a lean gadoid fish, was processed and stored at -10C, - 20C and -30C normal skinless fillets and as deep-skinned fillets. Properties related to lipid oxidation in the dark and light muscle tissues and in the two types of fillets were investigated after 6 to 9 months of storage. The lipid content and fatty acid profiles indicated the presence of relatively large amounts of triacylglycerols in the dark muscle. Prolonged storage at -10C and -20C resulted in a decrease in the content of n-3 polyunsaturated fatty acids (n-3 PUFA) in the dark muscle tissue. At the highest temperature, a reduction in n-3 PUFA is also indicated in the light muscle. Lipid oxidation as measured by 2-thiobarbituric acid reactive substances (TBARS) and reduction in alpha-tocopherol, was most pronounced in rite dark muscle. Evaluation of fillets by sensory analyses and TBARS values demostrated that industrial deep-skinning improves cold storage stability of saithe fillets.
Feist, S. W. (1995). Ultrastructural Aspects of Myxidium-Gadi (Georgevitch, 1916) (Myxozoa, Myxosporea) - Infections in Pollack (Pollachius- Pollachius L) and Saithe (P-Virens L). European Journal of Protistology 31, 309-317.
Plasmodia of Myxidium gadi attached to the gallbladder ep:thelium of two fish species, Pollachius pollachius and P. virens, were studied by transmission electron microscopy. Plasmodia were attached to the surface of the host epithelium by cytoplasmic extensions which contained fibrillar material and terminated in a basal plate which was separated from the epithelial cells by a thin amorphous layer. The gallbladder epithelium was characterised by the presence of numerous prominent vacuoles in the apical portion of the epithelial cells. Intracellular stages of M. gadi were not observed. The unattached surface of plasmodia was covered with numerous villous projections. Internally, membrane-bound inclusions up to 55 nm in diameter were observed. These were characterised by the presence of a laminated central core and a uniformly granular cortex. Clusters of generative cells were also prominent within the plasmodia. Spore formation proceeded by direct association of sporogonic cells, although pansporoblast formation was also occasionally observed. Sporoplasmosomes were abundant in the binucleate sporoplasm cell of immature spores and appeared to be formed from the endoplasmic reticulum.
Fortier, L., and Quinonez-Velazquez, C. (1998). Dependence of survival on growth in larval pollock Pollachius virens and haddock Melanogrammus aeglefinus: a field study based on individual hatchdates. Marine Ecology-Progress Series 174, 1-12.
The hatchdate frequency distributions (HFD) of pollock and haddock larvae sampled at monthly intervals west of Sable Island (Scotian Shelf, northwest Atlantic) in 1992 and 1993 were reconstructed for different age intervals (0-20, 21-40, 41-80 d) and corrected for aliasing due to sampling discontinuity and mortality-dispersion. The ratio of the HFD at a given age to the HFD at an earlier age was used as an index of the relative survival of larvae grouped into 5 d hatchdate cohorts. Pollock hatched from November to March and haddock from February to June. In pollock, seasonal variations in relative survival of the cohorts over the 21-40 and 41-80 d age intervals were correlated to strong variations in growth. In haddock, growth varied little over the hatching season and there was no significant Link with survival. For pollock, slow growth invariably resulted in low survival but fast growth resulted in either low or high survival, indicating that fast growth is a necessary but not sufficient condition for survival. Increased predation pressure late in the hatching season of both species could explain the decoupling of growth and survival in cohorts hatched in spring and early summer.
Gatermann, R., Hellou, J., Huhnerfuss, H., Rimkus, G., and Zitko, V. (1999). Polycyclic and nitro musks in the environment: A comparison between Canadian and European aquatic biota. Chemosphere 38, 3431-3441.
Nitro and polycyclic musks were determined for the first time in Canadian aquatic fauna such as lobster, winter flounder, American eel, lake trout, clams and mussels. Samples from densely populated areas, Halifax and the industrialized Miramachi estuary, showed relatively high concentrations of musk ketone (4-acetyl-1-tert-butyl-3,5-dimetyl-2,6- dinitrobenzene MK; maximum levels. mussels 2,200 ng/g lipid; winter Bounder muscle 2,700 ng/g lipid, clams 17,700 ng/g lipid) and HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8- hexamethylcyclopenta[g]-2-benzopyrane, 'galaxolide'; mussels 1,700 ng/g lipid; winter flounder 40 ng/g lipid; clams 3,000 ng/g lipid), while the samples from sparsely populated areas like Cap-Pele exhibited lower levels (MK maximum levels 130 ng/g lipid; HHCB maximum levels 16 ng/g lipid). Most samples contained relatively low concentrations of musk xylene (1-tert- butyl-3,5-dimetyl-2,4,6-trinitrobenzene, MX) and AHTN (7- acetyl-1,1,3,4,4,6-hexamethyl-tetrahydro-naphthalene, 'tonalide'). In contrast, in Western Europe, concentrations of the polycyclic musks HHCB and AHTN in fish presently exceed those of the nitro musks by about one to three orders of magnitude. These data seem to reflect the different application modes in Western Europe and North America with regard to the prevailing musk components in fragrances. Synthetic musks were not detectable in most commercial fish oils used in the preparation of aquaculture feed and fish lipids extracted in the 1980's in the laboratory, with the exception of a pollock (Pollachius virens) lipid from the Halifax area, which contained MX and MK at 350 and 64 ng/g lipid, respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.
Halliday, R. G., Cooper, C. G., Fanning, P., Hickey, W. M., and Gagnon, P. (1999). Size selection of Atlantic cod, haddock and pollock (saithe) by otter trawls with square and diamond mesh codends of 130-155 mm mesh size. Fisheries Research 41, 255-271.
The size selection of otter trawls equipped with square or diamond mesh codends with mesh sizes of 130-155 mm was examined for Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and pollock (Pollachius virens) in 14 cruises with research or commercial fishing vessels conducted off the Canadian Atlantic coast in 1988-1991, Square mesh codends gave a 50% retention length approximately 10% higher for cod and haddock than did diamond mesh codends of the same mesh size. Selection range of cod and haddock was approximately one third narrower for square mesh netting than for diamond mesh netting. Parameter estimates for pollock were too few to allow firm conclusions, but were generally similar to the other species. Present data were found to be consistent with selection data for cod and haddock published since 1980 for mainly smaller mesh sizes. When the present and published data sets were combined, square mesh was found to have 50% retention lengths that were 12% and 5% higher for cod and haddock, respectively, than for diamond mesh sizes, in the 130-155 mm range, Selection range for square mesh netting was 0.60 that of a diamond mesh with the same 50% retention length. For pollock, selection data were relatively few, and less consistent than for the other species, preventing firm conclusions. (C) 1999 Elsevier Science B.V. All rights reserved.
Hodneland, K., and Nilsen, F. (1994). On the Occurrence and Morphology of Gyrodactylus-Pterygialis From Saithe Pollachius-Virens in a Norwegian Fjord. Journal of Parasitology 80, 938-945.
A total of 308 Pollachius virens from a fjord near Bergen, western Norway, were examined for Gyrodactylus pterygialis over a 14-mo period; G. pterygialis showed the highest prevalence and density in winter/spring spring (November, January, March, and April pooled) but was absent in some months (August, September, and November). The morphology of the opisthaptoral hard parts of G. pterygialis were studied throughout the survey, and their variation is discussed with respect to host species, host locality, and different temperatures. On the basis of the present and previous descriptions, it is suggested that G. pterygialis is a parasite infecting gadine fishes of the genera Pollachius and Gadus, and that records from Pacific Eleginus and White Sea herring are distinct from G. plerygialis sensu Bychowsky and Poljansky, 1953.
Kalavati, C., and MacKenzie, K. (1999). The genera Ceratomyxa Thelohan, 1892, Leptotheca Thelohan, 1895 and Sphaeromyxa Thelohan, 1892 (Myxosporea : Bivalvulida) in gadid fish of the northeast Atlantic. Systematic Parasitology 43, 209-216.
The gall-bladders of four species of gadid fish from the North Sea and Norwegian waters were examined for myxosporeans. The host species were cod Gadus morhua L. (350 examined), haddock Melanogrammus aeglefinus (L.) (592 examined), saithe Pollachius virens (L.) (205 examined) and whiting Merlangius merlangus (L.) (368 examined). Four species of myxosporeans are redescribed from these fish. Ceratomyxa arcuata Thelohan, 1892 was the most common species and was found in whiting (42.8%) and cod (0.6%). Leptotheca informis Auerbach, 1910 was found only in whiting (6.5%). L. longipes Auerbach, 1910 was found only in haddock (6.2%). Sphaeromyxa hellandi Auerbach, 1909 was found in haddock (9.1%) and whiting (0.3%). None of the saithe examined, and no cod or haddock from Norwegian waters, was infected with these myxosporeans. All four species appear to have distributions limited to the Northeast Atlantic, with S. hellandi having a more northern distribution than the other three. The validity of reports of C. arcuata, L. informis and L. longipes from outside this area is discussed.
Katz, S. L., Shadwick, R. E., and Rapoport, H. S. (1999). Muscle strain histories in swimming milkfish in steady and sprinting gaits. Journal of Experimental Biology 202, 529-541.
Adult milkfish (Chanos chanos) swam in a water-tunnel flume over a wide range of speeds. Fish were instrumented with sonomicrometers to measure shortening of red and white myotomal muscle, Muscle strain was also calculated from simultaneous overhead views of the swimming fish, This allowed us to test the hypothesis that the muscle shortens in phase with local body bending. The fish swam at slow speeds [U<2.6 fork lengths s(-1) (=FL s(-1))] where only peripheral red muscle was powering body movements, and also at higher speeds (2.6>U>4.6 FLs(-1)) where they adopted a sprinting gait in which the white muscle is believed to power the body movements. For all combinations of speeds and body locations where we had simultaneous measurements of muscle strain and body bending (0.5 and 0.7 FL), both techniques were equivalent predictors of muscle strain histories. Cross-correlation coefficients for comparisons between these techniques exceeded 0.95 in all cases and had temporal separations of less than 7 ms on average. Muscle strain measured using sonomicrometry within the speed range 0.9-2.6 FL s(-1) showed that muscle strain did not increase substantially over that speed range, while tail-beat frequency increased by 140 %, While using a sprinting gait, muscle strains became bimodal, with strains within bursts being approximately double those between bursts. Muscle strain calculated from local body bending for a range of locations on the body indicated that muscle strain increases rostrally to caudally, but only by less than 4 %, These results suggest that swimming muscle, which forms a large fraction of the body volume in a fish, undergoes a history of strain that is similar to that expected for a homogeneous, continuous beam, This has been an implicit assumption for many studies of muscle function in many fish, but has not been tested explicitly until now. This result is achieved in spite of the presence of complex and inhomogeneous geometry in the folding of myotomes, collagenous myosepta and tendon, and the anatomical distinction between red and white muscle fibers.
Millischer, L., Gascuel, D., and Biseau, A. (1999). Estimation of the overall fishing power: A study of the dynamics and fishing strategies of Brittany's industrial fleets. Aquatic Living Resources 12, 89-103.
The present paper suggests a method for estimating the fishing power of vessels and for analysing fleet dynamics. The approach is based on quantification of stocks catchability (q), derived from fishing mortality coefficients (F) as calculated by virtual population analysis. Catchabilities for each harvested stock are thus estimated relatively to the fishing effort (f(n)) of each vessel, according to the equation: q = (F/f(n)). A linear model is then fitted to these catchabilities. The model allows the identification and quantification of trends in average mortality rates per fishing hour for each stock. Under some assumptions, trends are interpreted as variations in the overall fishing power of each fleet. The approach is applied to three industrial and semi-industrial fleets of Brittany (Lorient, Concarneau and Douamenez) and to the main gadoid stocks they exploit off the west coast of Scotland (ICES area Via), and in the Celtic Sea (ICES area VIIf,g,h) for Concameau. Results show large variations in fishing power. Particularly a marked increase trend in the fishing power exerted on saithe (Pollachius virens) is highlighted for the three fleets, over the period 1983-1989. These variations can be explained by the redirection of fishing strategies, which may occur on a large scale. Thus, we show how the collapse of saithe stock at first led the three fleets to intensify the harvesting of saithe, and from 1989 on, to adopt different strategies. The possible causes of the observed dynamics are discussed, as well as their consequences for fisheries management. In particular, the relevance of direct control of fishing effort as a regulatory tool is questioned. (C) Ifremer/Cnrs/Inra/Ird/Cemagref/Elsevier, Paris.
Penttila, J., and Dery, L. M. (1988). Age Determination Methods for Northwest Atlantic Species, pp. 135. NMFS Scientific Pub Office US Department of Commerce;, Seattle WA.
herring-clupea haddock-melanogrammus cod-gadus pollock-pollachius hake-merluccius, urophycis sea-bass-centropristis weakfish-cynoscion mackerel-scomber butterfish-peprilus redfish-sebastes
flounder-paralichthys, pseudopleuronectes, glyptocephalus, hippoglossoides, limanda, surf-clam-spisula quahod-arctica | jgk+5026b.
Piccolo, G., Manfredi, M. T., Hoste, L., and Vercruysse, J. (1999). Anisakidae larval infection in fish fillets sold in Belgium. Veterinary Quarterly 21, 66-67.
Fish fillets (n= 1760) sold on the Belgium market were examined for Anisakidae larval infection. Seven sea fish species were examined by means of the candling technique over a period of 4 months, from November 1996 to February 1997, Third-stage larvae of Anisakis simplex and Pseudoterranova decipiens were identified. A. simplex was the most abundant species with a prevalence of 84.5%, and was found in 192 of the examined fillets (10.9%), Pollock (Pollachius pollachius) was the most heavily infected fish species (82.9%), The prevalence in cod (Gadus morhua), saithe (Pollachius virens), and whiting (Merlangius merlangus) was 34.7%, 26.7%, and 15.4% respectively, The prevalence in the three other fish species examined was low, namely 8.9%, 6.6%, and 3.8% for ling (Molva molva), catfish (Anarchias lupus), and Northeast red fish (Sebastes marinus), respectively. Pollock was the fish species with the largest number of Anisakis larvae (7.8 larvae/kg fish fillet).
Quinonez-Velazquez, C. (1999). Age validation and growth of larval and juvenile haddock, Melanogrammus aeglefinus, and pollock, Pollachius virens, on the Scotian shelf. Fishery Bulletin 97, 306-319.
Daily growth increments on otoliths were used to estimate the age of larval and juvenile haddock, Melanogrammus aeglefinus, and pollock, Pollachius virens, collected on Emerald and Sable Island Banks, eastern Canada, between March 1991 and May 1993. The daily periodicity of the increments was validated from observations of reared larvae. For both species, the first increment was deposited the day after hatching and thereafter one increment was added daily. A Laird-Gompertz growth curve was fitted to length-age data for each species. Growth rates in haddock and pollock larvae varied significantly in different years. For haddock, the lowest growth rate was for the 1993 cohort, and growth rates in 1991 and 1992 cohorts were similar. For pollock, the 1993 cohort had the highest growth rate. The average growth rate was 0.21 mm/d for the first month and 0.42 mm/d for the second month for larval haddock and 0.18 mm/d for the first month and 0.23 mm/d for the second month for larval pollock. Growth continued exponentially after the transition from a primarily pelagic life to a predominantly demersal one, which occurred at an age of about 40-50 d. No indication of a cessation in growth was observed. Analysis of length-age data indicated that the accelerated growth of juveniles after 50 d in age could have reflected the exploitation of a more abundant food resource after settlement. Thus, pelagic and early demersal growth appear to represent distinct stanzas in the growth history of these gadoids.
Rangeley, R. W., and Kramer, D. L. (1995). Use of Rocky Intertidal Habitats By Juvenile Pollock Pollachius-Virens. Marine Ecology-Progress Series 126, 9-17.
We investigated patterns of distribution and foraging by young- of-the-year pollock Pollachius virens in the rocky intertidal zone. Pollock were sampled by beach seine in fucoid macroalgae and in open habitats at all stages of the tide, day and night throughout the summer. Their presence in shallow water at the high tidal stages indicated that at least part of the pollock population migrated across the full width of the intertidal zone (150 m) each tide. Densities in shallow water were much higher at low than at high tidal stages suggesting that a large influx of pollock moved in from the subtidal zone at low tidal stages and then dispersed into intertidal habitats at high tidal stages. There were few differences in pollock densities between algal and open habitats but abundances likely increased in the algal habitat at higher tidal stages when changes in habitat availability are taken into account. Densities were higher at night and there was an order of magnitude decline in pollock densities from early to late summer. In another study we showed that piscivorous birds are a probable cause of pollock summer mortality. Pollock fed on invertebrates from intertidal algae relatively continuously. The tidal migrations of juvenile pollock observed in this study and their use of macroalgae as a foraging and possibly a refuging habitat strongly suggests that the rocky intertidal zone may be an important fish nursery area.
Rangeley, R. W., and Kramer, D. L. (1995). Tidal Effects On Habitat Selection and Aggregation By Juvenile Pollock Pollachius-Virens in the Rocky Intertidal Zone. Marine Ecology-Progress Series 126, 19-29.
Fucoid macroalgae in the rocky intertidal zone are a potentially important foraging and refuging habitat for juvenile fishes. A dominant feature of this habitat is that its availability changes with the tides. Vegetated habitat availability changes in many other systems as well, yet little is known about the effects of these changes on animal distributions. We addressed this problem by studying young-of- the-year pollock Pollachius virens using visual transect surveys in the rocky intertidal zone. We examined tidal effects on pollock distribution, their depth and habitat preferences and the relationship between habitat use and patterns of aggregation. Nearly all the pollock population in our study area moved into the intertidal zone and alternated between aggregation in the open and dispersal in the algae. On rising tides, pollock moved from the subtidal zone to the open intertidal zone in large schools then dispersed among available depths and throughout algal habitats in small schools or as solitary fish. When in algae, pollock preferred the dense algal habitat over the sparse algal habitat. On falling tides, pollock schooled in the open habitat in downshore intertidal and subtidal zones. The main seasonal difference, from early to late summer, was an overall distributional shift towards the downshore open habitat and the subtidal zone and a preference for greater depths in the intertidal zone. These results support the hypothesis that pollock were using both refuging and schooling antipredator tactics during intertidal zone migrations. We suggest that rocky shores are important nurseries for juvenile pollock.
Salvanes, A. G. V. (1995). Pollack (Pollachius-Pollachius) Stock Size Development and Potential Influence On Cod (Gadus-Morhua) Mariculture in a West Norwegian Fjord. Fisheries Research 24, 223-242.
This study examines density-dependent mortality of pollack, a major cod predator, and cod, before and after juvenile cod were released on a large scale in Masfjorden, western Norway. The development in stock size, mortality by age group and diet are emphasised, and results for pollack and cod are compared. Population parameters for pollack are estimated using a combination of the catch per unit effort (CPUE) method and a general cohort analysis technique. The estimates for cod originate from a combination of the CPUE method and tag- release-recapture experiments and have been published earlier. The diet studies are based on pollack and cod subdivided into predator size groups for four seasons at a period before large- scale juvenile cod releases. During this period, but also after releases, the mortality patterns, stomach analysis and the progression in prey (1-group) and predator (2+-group) abundance demonstrate cannibalism as well as that pollack and cod were feeding on each other's juveniles in Masfjorden. Density- dependent predation mortality and growth seem to be an important regulatory mechanism for pollack and cod stocks in Masfjorden. This may explain the unsuccessful cod mariculture in this fjord.
Santos, M. B., Pierce, G. J., Boyle, P. R., Reid, R. J., Ross, H. M., Patterson, I. A. P., Kinze, C. C., Tougaard, S., Lick, R., Piatkowski, U., and Hernandez-Garcia, V. (1999). Stomach contents of sperm whales Physeter macrocephalus stranded in the North Sea 1990-1996. Marine Ecology-Progress Series 183, 281-294.
Stomach contents of 17 sperm whales Physeter macrocephalus stranded in Scotland and Denmark during 1990-96 were analysed. All were sub-adult or adult males and stranded between November and March. They had presumably entered the North Sea during their southward migration from feeding grounds in Arctic waters. Other studies indicate that the majority of the whales were apparently healthy. The diet of these whales was found to consist almost entirely of cephalopods, principally squid of the genus Gonatus (hereafter 'Gonatus', but probably G. fabricii, an oceanic species characteristic of Arctic waters). The other prey species identified were also mostly oceanic cephalopods: the squids Histioteuthis bonnellii, Teuthowenia megalops and Todarodes sagittatus and the octopus Haliphron atlanticus. Although these results are consistent with other recent studies in the area based on single stranded whales, they differ from results of work on whales caught during commercial whaling operations in Icelandic waters (1960s to 1980s) in that little evidence of predation on fish was found in the present study. Remains of single individuals of the veined squid Loligo forbesi, the northern octopus Eledone cirrhosa and the saithe Pollachius virens provided the only possible evidence of feeding in the North Sea. We infer that sperm whales do not enter the North Sea. to feed. The timing, and large and uniform sizes of the Gonatus species eaten (most had mantle lengths in the range 195 to 245 mm), as estimated from measurements of the lower beaks, and the seasonality of the strandings is consistent with the whales having fed on mature squid, possibly spawning concentrations-as has recently been reported for bottlenose whales. Assuming that the diet recorded in this study was repre sentative of sperm whales during the feeding season, as much as 500000 t of Gonatus could be removed by sperm whales in Norwegian waters each year and up to 3 times that figure from the eastern North Atlantic as a whole. Evidence from other studies indicates that Gonatus is an important food resource for a wide range of marine predators in Arctic waters.
Schubring, R. (1999). Influence of twice-freezing on quality parameters of Pollack (Pollachius virens) fillets. Deutsche Lebensmittel-Rundschau 95, 161-171.
Single and double frozen fillets are differentiated from each other by same of the parameters investigated. As a role, the formaldehyde content is lower in SF fillets than in DF fillets. Beside the chemical parameters physical measures are influenced, too. The lightness (L*) increases due to refreezing. While twice-freezing causes an increase in yellowness (b*) as well, the redness (a*) seems to be unaffected. Texture changes measured instrumentally revealed differences between SF and DF fillets expressed by penetration force or hardness derived from TPA. The same is valid for the firmness and rubberiness evaluated by sensory which both increase by refreezing. Beside these, also the cohesiveness and juiciness (both are lowered) and the fibrousness and fibre size (both are higher) are markedly changed by double freezing. Concerning flavour, the double frozen fillets show reduced freshness and are more stale and fishy. This deterioration is known from frozen storage trials and significant only when using pre- and in-rigor fillets. Under commercial conditions the fillets are mostly processed post-rigor. Therefore, it seems to be obvious that the final battered and breaded products processed using refrozen blocks of fillets are not of lower quality compared with those derived from single frozen ones. The investigation methods used allow to differentiate between SF and DF fillets, but it is not possible to fix limits for the time being.
Serennes, F., Chopin, C., Mastail, M., and Vallet, J. L. (1996). Influence of high pressure on texturization of coalfish (Pollachius virens) pulp. Sciences Des Aliments 16, 307-316.
Protein texturisation under high pressure was studied as a means of making use of fish mince resulting from industrial sources. Different factors may have an effect of the efficiency of the process: pressure, temperature, salt and setting time (contact time between the salt and the mice), It was noticed from statistical analysis that there was a quadratic effect of pressure and temperature and a linear effect of salt concentration as well as an interaction between temperature and time on the texture of the final product.
Smith, G. W., Glass, C. W., Johnstone, A. D. F., and Mojsiewicz, W. R. (1993). Diurnal Patterns in the Spatial Relationships Between Saithe, Pollachius-Virens, Schooling in the Wild. Journal of Fish Biology 43, 315-325.
Sterud, E. (1998). Ultrastructure of Spironucleus torosa Poynton & Morrison, 1990 (Diplomonadida : Hexamitidae), in cod Gadus morhua (L.) and saithe Pollachius virens (L.) from south-eastern Norway. European Journal of Protistology 34, 69-77.
Hexamitid flagellates from the rectum of cod and saithe were studied by scanning- and transmission electron microscopy. They were identified as Spironucleus torosa, having characteristic posterio-lateral depressions with central protrusions (tori), from which the recurrent flagella emerged. This is the first time that this species has been reported from European waters, and it is also the first record of saithe as a host species. The study presents new information on the ultrastructure of the species. The arrangement of the microtubules accompanying the recurrent flagella is described and found to be different from that of ether species of Spironucleus. Parts of the extensive microtubular cytoskeleton of the posterior end are also described. Along the recurrent flagella, between the cytostome and the striated lamina, it was found an electrolucent or hollow tube not earlier described from S. torosa. Bacteria, possibly ectosymbiotic, were found to be situated in the posterio-lateral depressions around the tori.
Stromnes, E., and Andersen, K. (1998). Distribution of whaleworm (Anisakis simplex, Nematoda, Ascaridoidea) L3 larvae in three species of marine fish; saithe (Pollachius virens (L.)), cod (Gadus morhua L.) and redfish (Sebastes marinus (L.)) from Norwegian waters. Parasitology Research 84, 281-285.
The frequency distribution of Anisakis simplex L3 larvae between host tissues was investigated in three host species: saithe, cod and redfish. Fish were sampled from Norwegian coastal waters and examined for the presence of A. simplex in muscle and viscera. In all three of the host species, A. simplex larvae were most frequently detected in the viscera; the percentages of total infection for saithe, cod and redfish were 99.6%, 97.8% and 88.0%, respectively. In general, the distribution patterns of A. simplex L3 between muscle and viscera were not significantly affected by host size. The observations that distributions vary between species and are not affected by host size do not support an earlier hypothesis which states that A. simplex L3 distributions are determined by an optimal pre-encapsulation migratory distance within host tissues. In contrast, it is suggested that A. simplex L3 distributions are governed by the conditions encountered within host tissues, and are possibly related to the availability of nutrients.
Suquet, M., Petton, B., Normant, Y., Dosdat, A., and Gaignon, J. L. (1996). First rearing attempts of pollack, Pollachius pollachius. Aquatic Living Resources 9, 103-106.
van der Meeren, T., and Lonoy, T. (1998). Use of mesocosms in larval rearing of saithe [Pollachius virens (L.)], goldsinny [Ctenolabrus rupestris (L.)], and corkwing [Crenilabrus melops (L.)]. Aquacultural Engineering 17, 253-260.
Pilot experiments were carried out in mesocosms (5.3 m(3) plastic bag enclosures) for larval rearing of the commercially important saithe [Pollachius virens (L.)], and two wrasse species, goldsinny [Ctenolabrus rupestris (L.)] and corkwing [Crenilabrus melops (L.)] which are both used as cleaner-fishes for control of sea-lice infestations in Atlantic salmon farming. Fertilized saithe eggs were collected from natural spawning in a simple and inexpensive tank system. Goldsinny and corkwing eggs were obtained by stripping mature individuals collected from the sea. Egg mortality during incubation was low in all species. Larvae were released in the rearing enclosures a few days after hatching and fed natural plankton (mainly copepod nauplii). Survival through metamorphosis was low for saithe (3%), which may be attributed to specific environmental requirements, in terms of water quality, in this species. Survival in the wrasse was good (20-40%), indicating that the use of mesocosms may have potential for mass-production of these species. (C) 1998 Elsevier Science B.V. All rights reserved.
Windram, J. D., Harper, A. A., and Watt, P. W. (1993). The Effect of Temperature On Pacemaker Activity in the Isolated Heart of the Marine Teleosts Saithe (Pollachius-Virens) and Plaice (Pleuronectes-Platessa). Journal of Physiology-London 473, P255-P255.