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Anarhichas lupus is a boreo-Arctic species with biological characteristics often associated with vulnerability to over-exploitation. Although not commercially targeted in the North Sea, A. lupus is a bycatch species in mixed demersal fisheries. Here we provide an overview of the status of A. lupus in the North Sea, as observed from commercial landings and fishery-independent trawl survey data. A. lupus was once common across much of the central and northern North Sea but, since the 1980s, have declined in abundance, demographic characteristics (reduced size) and geographical range, with the shallower and more southerly parts of its range most impacted. A. lupus is still relatively frequent in the northern North Sea, where fishing intensity, though decreasing, is high. Bycatch through fishing remains a potential threat and, considering the likely impacts of predicted climate change on cold-water species, risks of further regional depletion and/or range contraction remain. Whether or not A. lupus is able to re-establish viable populations in former habitat in UK coastal waters is unknown. Given the lack of data, the precautionary principle would suggest that manageable pressures be minimised where the species and its habitat are at risk of further impacts, and more regular assessments of population status be undertaken. This article is protected by copyright. All rights reserved.

The Atlantic wolffish (AW) and the spotted wolffish (SW) are long-lived fish found in the North Atlantic and Arctic oceans and are respectively classified as special concern and threatened species, mainly due to fisheries bycatch. To better understand health issues associated with the care of these species in public aquaria, reports from all necropsies performed in 2 zoological institutions between 2009 and 2019 were reviewed (31 AW and 8 SW). These wolffish were fed with a similar fish-based diet and kept in multi-species exhibits with comparable environmental parameters. The most frequent necropsy findings were the presence of xanthomas (AW: 41.9%; SW: 75.0%), nephrocalcinosis (AW: 42.9%; SW: 75.0%) and urocystoliths (AW: 6.5%; SW: 62.5%). Xanthomas were mostly located at the base of pectoral fins and were characterized by extensive granulomatous inflammation centered on accumulations of partly mineralized degenerate fatty material, mainly composed of cholesterol crystals. Nephrocalcinosis was characterized by the deposition of calcium salts within the renal tubules and was commonly associated with tubular necrosis. The aquarium-housed wolffish were fed a coldwater fish-based diet. However, the natural diet of wolffish is composed mostly of invertebrates such as urchins and crustaceans. Differences in nutrient composition between these diets, such as lipid and mineral content, may have contributed to the development of xanthomatosis, nephrocalcinosis and urocystolithiasis in wolffish housed in these institutions.

Homing and site fidelity of Atlantic wolffish Anarhichas lupus was studied at the main spawning ground and four different feeding grounds in Icelandic waters. A total of 883 fish were tagged with T-bar anchor tags, whereof 349 fish also received an internally implanted data storage tag (DST). The DSTs data revealed consistent year-to-year migrations between spawning grounds and feeding grounds. Arrival time at the main spawning ground was similar for males and females, but males departed two months later, suggesting that peak of hatching of larvae was in late February. Homing was estimated to be 93% for the main spawning ground and 87% for feeding grounds. Fish tagged at the main spawning ground did not exclusively migrate to one feeding ground during the feeding season, and fish tagged at each feeding ground migrated to more than one potential spawning ground. Fish tagged at the southeast feeding ground appear to be isolated from the other areas investigated. Atlantic wolffish in Icelandic waters is currently managed as one single stock, hence the single stock management approach might need to be reconsidered.

The Atlantic wolffish (Anarhichas lupus) is listed by Canada’s Species at Risk Act as a species of special concern. Effective conservation strategies rely on accurate knowledge of habitat requirements, distribution, and vulnerabilities; however, current management plans cite lack of wolffish habitat data as a key limitation. For this study, coastal Atlantic wolffish denning habitat was characterized and mapped with high-resolution multibeam data and seafloor video in Conception Bay, Newfoundland. Four Atlantic wolffish dens, used for feeding, spawning, and egg-guarding, were surveyed and mapped. On the basis of the geomorphology and substrate of these dens, a supervised classification was applied to the multibeam bathymetry and backscatter data to identify other potential denning areas. Predicted denning habitat, limited by the occurrence of suitable rocky substrate, is most prevalent in shallow waters (2 (5.9%) of the study area. Shallow denning habitat is exposed to seasonal maximum temperatures that exceed the threshold for normal Atlantic wolffish egg development, a potential vulnerability for nearshore wolffish. As management efforts progress, this information will guide research and prioritization of conservation areas.

Biological data were retrieved from 374 female Atlantic wolffish (Anarhichas lupus) collected from 2001–2006 at A. lupus main spawning grounds in Iceland and at two other locations with different sea temperature regimes to investigate spatial and temporal difference in fecundity and indications of atresia. There was no spatial difference in fecundity but temporal difference was found, and fecundity decreased in time, clearly indicating the presence of atresia. A. lupus that was 57 cm long was 11% more fecund in the year 2003 than in 2005. Egg numbers decreased about 20% from June to October for 67 cm long A. lupus. There was a positive relationship between fecundity and condition of the fish.

Shorthorn sculpin (Myoxocephalus scorpius) and large cod (300–400 g body weight) are important predators on newly settled 0-group cod (Gadus morhua) and saithe (Pollachius virens) in Porsangerfjorden in northern Norway. The Atlantic wolffish (Anarhichas lupus) used to be abundant but is now very rare in the fjord. Video recorded experiments showed that interactions between shorthorn sculpins, wolffish and large cod affected predation rates on small 0-group cod and saithe in tanks with a gravel, cobble and seaweed (Fucus serratus) substrate. We found that sculpins were unable to catch 0-group specimens when they were the only predatory species in the experimental tank and the lights were left on 24 h a day (to simulate the midnight sun), and that they did not even attempt to catch them. The addition of a large cod to the tank increased sculpin attack rates and predation success significantly. The “cod effect” was due to 0-group specimens avoiding attacks by escaping into the cobbles or vegetation, were they could be more easily reached by the sculpins. When tanks were supplemented with a wolffish in addition to the cod, both sculpin and cod predation success was lowered by approximately 50% in the 24-h light regime. When the experimental setup was changed to a day/night light cycle, however, the wolffish presence had no effect. Also, sculpins in tanks without cod and wolffish went from consuming zero to 29% of the 0-group specimens in the tank when the light regime went from 24-h light to day/night. Sculpins and cod were most effective predators on 0-group cod and saithe at dusk/night/dawn, and the presence of a cruising predator like cod increased sculpin predation success and probably vice versa. The experimental data indicate that rebuilding wolffish stocks in the fjord system may make the bottom substrate more protective for 0-group specimens of cod and saithe, by limiting the foraging volume of an effective bottom-dwelling 0-group predator like the sculpin. Further field and lab studies must be conducted before the reported findings optionally can be turned into a management advice.

Stable isotope analyses of zooarchaeological material can be used to examine ecological variability in exploited species at centennial to millennial scales. Climate change is a notable driver of marine ecosystem change, although historical fishing is also likely to have impacted past marine systems. Fishing removes the oldest and largest individuals and may thereby result in shorter trophic pathways and reduced niche width of predatory fish species. In the current study we examine the trophic niche of Atlantic cod, haddock and Atlantic wolffish, in the last millennium using δ13C and δ15N values of bone collagen. We report a lower trophic level of Atlantic cod and haddock but higher level of wolffish in present times, following centuries at consistent and higher trophic levels of Atlantic cod. This results in a concurrent converging trophic niche of the demersal fish. We suggest that the current data set provides a valuable historical baseline facilitating interpretation of current variability in the trophic ecology of northern demersal fish.

Biological data were retrieved from 3694 female Atlantic wolffish Anarhichas lupus collected in Icelandic waters at four locations during the breeding season using a long–term study spanning from 2002 to 2013. The main objective was to investigate reproduction investment and timing. In the main spawning ground, little temporal differences were observed. In contrast, the peak of the spawning season was different among spawning grounds, suggesting spatial differences in the timing of reproduction. The size of females A. lupus was related to the spawning time with the larger fish spawning earlier than smaller ones. In addition, no significant pattern was found between temperature and spawning time. Except at its main spawning area where spawning begins in late September, spawning usually began in late August or beginning of September and was completed in early November.

Adult Atlantic Wolffish, Anarhichas lupus, have a heterodont oral dentition consisting of long caniniform teeth in the symphysial regions of the dentaries and premaxillae and large molariform teeth posteriorly on the dentaries, dermopalatines, and vomer. Teeth are ankylosed to the bone of attachment. Wolffish use the caniniform teeth to capture prey including molluscs, crustaceans, echinoderms, and, less commonly, fishes. Prey are transported posteriorly and crushed between the molariform teeth. The molariform teeth of adults fit closely together despite individually variable shapes and sizes in a space-filling pattern that we term anamestic. Adult wolffish have an unusual tooth replacement pattern in which teeth are lost and subsequently replaced all at once, a pattern called simultaneous replacement. We used dissection, osteology, histology, and micro-computed tomography (CT) to study tooth replacement in a series of Anarhichas lupus from the western North Atlantic. Tooth development is intraosseous, wi...

In this study, utilization of catch-quota balancing mechanisms in the Icelandic demersal fishery, which allow for individual transferable quota to be transformed among species and transferred between years, is analyzed to determine whether annual catches closely adhere to total allowable catches on average. Icelandic landings data for 14 demersal fish species during 2001–2013 are compared to implemented total allowable catches as well as catch limits recommended by the Marine Research Institute (MRI) and a proxy for annual market values. Landings surpassed legal limits of total allowable catch in 27% of the cases (landings by species by fishing year), mostly due to species transformations, but TAC overages were not consistent for any species. Instead, catches of some species were consistently less than legal limits, with some indications that landings were related to profitability (i.e. landings were correlated with market value). However, landings surpassed MRI recommendations in 67% of the cases, and landings of four species (Atlantic wolffish, haddock, monkfish and redfish) consistently exceeded MRI recommendations. Therefore, discrepancies between scientific recommendations for catch limits and quotas selected through the political process may represent a higher risk to long-term sustainability than catch-quota balancing mechanisms.

Herein, we review and synthesize results from a series of research projects that were conducted to evaluate the role of Greenland sharks (Somniosus microcephalus) in the marine ecosystem in Kongsfjorden, Svalbard, Norway. A total of 76 sharks were caught on baited lines during the summers of 2008 and 2009 for these investigations. All of these animals, including the largest shark, a female weighing 700 kg, were sexually immature. Approximately half of the gastrointestinal tracts (GITs, N = 33) examined contained seal tissue (42.3 %), and some also contained minke whale (Balaenoptera acutorostrata) tissue (18.2 %). Atlantic cod (Gadus morhua), Atlantic wolffish (Anarhichas lupus) and haddock (Melanogrammus aeglefinus) were the dominant fish species consumed by the sharks. These fish species were found in 39.4, 18.2 and 18.2 % of the GITs, respectively. Many of the fishes were swallowed whole, including an Atlantic wolffish weighing 8.6 kg. Satellite pop-up tags deployed on 20 of the sharks showed that they travelled in the water column from the surface to depths greater than 1500 m, encountering temperatures from −1.5° to 7.4°. Accelerometers deployed on six of the sharks showed that they swim extremely slowly, with average speeds of 0.34 m/s and burst speeds of only twice this value. Various types of circumstantial evidence, including the condition of the seals and fishes found in the sharks’ stomachs, indicate that they are not only scavengers, but also active predators of both fish and mammalian prey. Given the swim speed of these sharks, we suggest that the only way they could successfully capture a healthy seal is via cryptically approaching seals that are asleep in the water. Greenland sharks clearly play a significant role as large predators in the Kongsfjorden marine ecosystem, a fact that has been largely overlooked until recently.

We conducted a literature review of reported temperature, salinity, pH, depth and oxygen preferences and thresholds of important marine species found in the Gulf of St. Lawrence and Scotian Shelf region. We classified 54 identified fishes and macroinvertebrates as important either because they support a commercial fishery, have threatened or at risk status, or meet one of the following criteria: bycatch, baitfish, invasive, vagrant, important for ecosystem energy transfer, or predators or prey of the above species. The compiled data allow an assessment of species-level impacts including physiological stress and mortality given predictions of future ocean physical and biogeochemical conditions. If an observed, multi-decadal oxygen trend on the central Scotian Shelf continues, a number of species will lose favorable oxygen conditions, experience oxygen-stress, or disappear due to insufficient oxygen in the coming half-century. Projected regional trends and natural variability are both large, and natural variability will act to alternately amplify and dampen anthropogenic changes. When estimates of variability are included with the trend, species encounter unfavourable oxygen conditions decades sooner. Finally, temperature and oxygen thresholds of adult Atlantic wolffish (Anarhichas lupus) and adult Atlantic cod (Gadus morhua) are assessed in the context of a potential future scenario derived from high-resolution ocean models for the central Scotian Shelf.

During winter, the coastal waters of Newfoundland can be considered a ‘freeze risk ecozone’ for teleost fishes, where the shallower habitats pose a high (and the deeper habitats a low) risk of freezing. Atlantic (Anarhichas lupus) and spotted (Anarhichas minor) wolffish, which inhabit these waters, reside at opposite ends of this ecozone, with the Atlantic wolffish being the species facing the greatest risk, because of its shallower niche. In order to resist freezing, this species secretes five times the level of antifreeze protein (AFP) activity into the plasma than does the spotted wolffish. The main basis for this interspecific difference in AFP levels is gene dosage, as the Atlantic wolffish has approximately three times as many AFP gene copies as the spotted wolffish. In addition, AFP transcript levels in liver (the primary source of circulating AFPs) are several times higher in the Atlantic wolffish. One explanation for the difference in gene dosage and transcript levels is the presence of tandemly arrayed repeats in the latter, which make up two-thirds of its AFP gene pool. Such repeats are not present in the spotted wolffish. The available evidence indicates that the two species diverged from a common ancestor at a time when the ebb and flow of northern glaciations would have resulted in the emergence of shallow water ‘freeze risk ecozones’. The results of this study suggest that the duplication/amplification of AFP genes in a subpopulation of ancestral wolffish would have facilitated the exploitation of this high-risk habitat, resulting in the divergence and evolution of modern-day Atlantic and spotted wolffish species. Database Nucleotide sequence data are available in the GenBank database under the accession numbers AWG1-4, JQ040521, JQ040515, JQ040516, JQ040517, AWE1-3, JQ040522, JQ040523, JQ040524, SWG1-3, JQ040518, JQ040519, and JQ040520

Northern and Spotted Wolffishes (Anarhichas denticulatus and A. minor) are demersal marine fishes listed as “threatened” in Canadian waters. Both species have unusually large benthic eggs and large size at hatch, which should reduce passive dispersal. We examined population differentiation with microsatellite and AFLP loci across the ranges of both species in the North Atlantic Ocean. Although significant population structure was documented, differentiation was less than expected based on knowledge of life history characteristics. Significant differentiation was found in Northern Wolffish between the Barents Sea and other samples based on both microsatellite and AFLP data. In contrast, population structure in the Spotted Wolffish was notably weaker, particularly with microsatellites. Both species were characterized by low genetic diversity for marine fishes and had significantly lower genetic diversity than the congeneric Atlantic Wolffish. This finding was consistent with the conservation status of these three species and suggests potential vulnerability to over-exploitation in Northern and Spotted Wolffishes.

Genetic variation was assessed in Atlantic wolffish, Anarhichas lupus, across the North Atlantic Ocean using microsatellite and amplified fragment length polymorphism (AFLP) markers. Despite unusual life history attributes such as large benthic eggs, large larvae, a limited pelagic stage and relatively sedentary adults, which suggest potential for strong population structure, range-wide FST values were comparable to other marine fishes (≤0.035). Nevertheless, both significant genetic differentiation among regions and isolation by distance were observed, suggesting limited dispersal in this species. AFLP loci, evaluated on a subset of samples, revealed slightly higher FST values, but similar patterns of differentiation and isolation-by-distance estimates, compared to microsatellites. The genetic structure of Atlantic wolffish has likely been shaped by its post-glacial history of recolonization, North Atlantic current patterns and continuity of habitat on continental shelves.

To produce energy, mitochondria use oxidative phosphorylation, a multistep process involving several integrated reactions influenced by temperature. In order to identify which step in the process was most sensitive to temperature in a cold-temperate ectothermic species, we measured the thermal sensitivity of mitochondrial oxidative phosphorylation, as well as the thermal sensitivity of each individual step in this process, in mitochondria isolated from the heart of Atlantic wolffish (Anarhichas lupus). The thermal sensitivity of oxidative phosphorylation (coupled, ADP-stimulated), measured in the presence of pyruvate and malate as substrates, and those of Complexes II and IV activities were the same over the whole range of assay temperatures (5 to 35 °C). In contrast, the thermal sensitivity of Complexes I and III, ATPase, pyruvate dehydrogenase and citrate synthase could not be correlated with the thermal sensitivity of oxidative phosphorylation. The first step in the process of oxidative phosphorylation to be negatively affected by increased temperature was shown to be Complex III, followed by the Complex I. This occurred at temperatures above the tolerance limit and well above the range of temperatures occupied by the species. Our results identify specific steps within the electron transport system as potential control point limiting the capacity of Atlantic wolffish cardiac mitochondrial metabolism in response to changes in temperature.

Sixteen tetranucleotide and dinucleotide microsatellite markers were isolated from Atlantic wolffish, Anarhichas lupus, following a microsatellite enrichment procedure using probe-labelled magnetic beads. These microsatellites were intended for use in Atlantic wolffish as well as in two closely related species, spotted wolffish, Anarhichas minor, and northern wolffish, Anarhichas denticulatus. As all three species are of conservation concern in Canadian waters and as forensic wildlife cases may arise for this genus, microsatellite markers were assessed to determine how well they differentiate these species from one another and to estimate probability values that could be expected for identification of individuals to species.

This study contributes to the identification of an adequate cryopreservation medium for wolffishes sperm (Anarhichas minor and A. lupus). Our results also confirm the presence of antifreeze proteins in the seminal fluid of the Atlantic wolffish (Anarhichas lupus) that could facilitate the process of cryoconservation in association with increased post-thaw motility and fertilization rates. Cryo-Fish, a commercial diluent was the most efficient in our trials, with 80% motility post-thaw.

We investigated activity levels of metabolic and digestive enzymes in Atlantic wolffish (Anarhichas lupus) and their relationships with growth, ration level, and type of food during the first 50 days after hatch. Newly hatched wolffish were divided among three experimental groups differing in feed and ration (formulated feed in excess (FF), a maintenance ration of Artemia (LA), and Artemia in excess (EA)) that generated different growth rates. A principal component analysis revealed that activities of the glycolytic enzymes lactate dehydrogenase (LDH) and pyruvate kinase (PK) were associated with mass gain, while those of the aerobic enzymes citrate synthase and aspartate aminotransferase (AAT), and digestive enzymes (lipase and trypsin) were related to time (days) after hatch. Food restriction or food type allowed the observation of a direct relationship between the activities of trypsin and those of associated metabolic enzymes AAT and glutamate dehydrogenase in the LA group (Pearson's R of 0.71 and 0.59, respectively), as well as between the activities of amylase and those of LDH and PK (Pearson's R of 0.62 and 0.48, respectively) in the FF group. The adaptative importance of these patterns during early development of wolffish and their relationship to feeding conditions are examined.

Background: The biologic attributes of the endocrine pancreas and the comparative endocrinology of islet amyloid polypeptide (IAPP) of fish are not well described in the literature. This study describes the endocrine pancreasof one teleostean fish. Ten captive Atlantic wolffish (Anarhichas lupus)from the Montreal Biodome were submitted for necropsy and their pancreata were collected. Results: Grossly, all the fish pancreata examined contained 1-3 nodules of variable diameter (1-8 mm). Microscopically, the nodules were uniform, highly cellular, and composed of polygonal to elongated cells. Immunofluorescence for pancreatic hormones was performed. The nodules were immunoreactive for insulin most prominent centrally, but with IAPP and glucagon only in the periphery of the nodules. Exocrine pancreas was positive for chromogranin A. Not previously recognized in fish, IAPP immunoreactivity occurred in α, glucagon-containing, cells and did not co-localize with insulin in β cells. The islet tissues were devoid of amyloid deposits. IAPP DNA sequencing was performed to compare the sequence among teleost fish and the potency to form amyloid fibrils. In silico analysis of the amino acid sequences 19-34 revealed that it was not amyloidogenic. Conclusions: Amyloidosis of pancreatic islets would not be expected as a spontaneous disease in the Atlantic wolffish. Our study underlines that this teleost fish is a potential candidate for pancreatic xenograft research.

The green sea urchin, Strongylocentrotusdroebachiensis, exhibited immediate behavioural responses to waterborne chemosensory cues from two durophagous predators, the Atlantic wolffish, Anarhichaslupus, and the edible crab, Cancerpagurus; as well as from crushed conspecifics and crushed blue mussels, Mytilusedulis. The response patterns were dose dependent and diet dependent. Strong responses were elicited by water conditioned by echinivorous wolffish (97.5%), undiluted urchin extract (73%), undiluted mussel extract (52.5%), and by water conditioned by echinivorous crab (45%). In contrast, urchin extract diluted to 1%, mussel extract diluted to 10%, and water conditioned by predators on a mussel diet elicited weak responses (~20%). Infection by the endoparasitic nematode Echinomermellamatsi had no significant effect on the response pattern of S. droebachiensis. There was no conclusive evidence of an alarm response to the predators per se, as the weak response to stimuli from non-echinivorous wolffish and crab, as well as from the seastar Asteriasrubens, may have been caused by chemical cues transmitted from their mussel diet. The diet-dependent response to predators suggests that active predators were labelled by chemical cues from their echinoid prey. The chemical cue from echinivorous wolffish acted as both an arrestant and as a repellent, whereas the response to other cues was predominantly or exclusively repellent. The response to echinivorous wolffish was quantitatively stronger than, and qualitatively different from, the response to other stimuli, including undiluted urchin extract. The wolffish is apparently being labelled by a latent chemical cue which derives its potency from activation by, or interaction with, substances in the digestive system of the wolffish. We interpret this novel phenomenon as evidence of alarm signal magnification. The induced behavioural modifications demonstrate the green sea urchins' ability to detect chemical cues associated with active durophagous predators, and would therefore seem to have adaptive potential as a predator defence mechanism.

Concern about the overexploitation of wild aquatic resources, the slow recovery of the groundfish fisheries and the need to encourage the diversification of the mariculture industry of the province of Quebec (Canada) all provided strong incentive to explore the potential of a wide selection of marine and anadromous fish species for cold-water mariculture. Starting from a list of over 45 indigenous fish species of potential commercial interest, a biotechnical review was initiated. Technical sheets for each species were produced and aquaculture-based selection criteria covering three aquaculture approaches of development (complete life cycle, on-growing and stock enhancement) were examined. Species were ranked according to their degree of suitability for the given biological parameters. The final classification analysis within the complete life cycle production strategy positioned the Atlantic wolffish as the top candidate species (91%) followed by the spotted wolffish and Arctic charr (87%). Growth rate, optimal growth temperature, duration of the weaning period, minimal lethal temperature, larval size and feed requirements were the determining criteria. The on-growing scenario final results ranked Arctic charr first (84%) followed by Atlantic cod (79%) and Atlantic halibut (74%) mostly owing to their growth rate at low temperature and optimal growth temperature criteria. Stock enhancement programmes should concentrate their efforts on the striped bass (56%), the haddock (54%) and the Atlantic sturgeon (34%) based on their growth rate, fishery status, landing price and the availability of impact studies.

The spotted wolffish Anarhichas minor (Olafsen), with its rich and tasty fillets, popular skin and high growth rates in captivity, is a promising candidate for cold-water aquaculture. We have established a production line for the wolffish during 5 years of active research on the biology of the species. Our broodstock, sampled from the Barents Sea, has mainly spawned during autumn. The females must be stripped as soon as possible after ovulation. The best egg batches have shown c. 100% fertilization and survival rates between 60% and 80% during the 800- to 960-daydegrees-long incubation period. Rearing temperatures of 6 °C, 8 °C, ambient and decreasing temperatures have turned out to be satisfactory for survival. Treatment with 150 p.p.m. glutardialdehyde twice a month is recommended to control microorganism growth on eggs. Premature hatching has been a problem in individual egg batches; the reasons are not fully understood. Normally hatched individuals are ≈ 22 mm long and well developed, with a small yolk sac, which is completely resorbed after about 4 weeks at 6–8 °C. The fry have been successfully start fed on formulated feed as well as Artemia. Highest early growth rates have been noted at 8 °C, but overall survival was best at 6 °C. On-growth of spotted wolffish juveniles fed formulated dry floating feed at low temperatures in shallow raceways has been promising. After 2, 3 and 4 years, the mean weights of the first generation produced in aquaculture were 0.7, 2.7 and 5.1 kg respectively. These individuals now make up the broodstock at a recently established commercial production facility.

The use of behavioural observations on marine fish larvae has a long history and has added considerable depth to our understanding of the ecological adaptations of larval fish. In marine fish larviculture we are trying to domesticate wild animals. Behavioural observation, in conjunction with growth and survival information, is a powerful tool for understanding the behavioural adaptations of larvae. This paper reports on the results of experiments conducted on the first-feeding of two species of marine larvae. Results of experiments carried out on lumpfish ( Cyclopterus lumpus ) fed the same density of live prey in pulses (twice or three times/day) or continuously, demonstrated that growth and feeding behaviour was significantly higher in the pulse treatments. A second set of experiments was performed on weaning of Atlantic wolffish ( Anarhichas lupus ) larvae. Live prey and pelleted food were offered to larvae from the onset of first-feeding. Observations on larvae indicated that over the first few weeks, larvae fed mostly on live prey with some pellet feeding. This pattern changed as larvae grew and by eight weeks larvae fed mostly on pelleted feed. In this example, the behaviour of the larvae provided a schedule which could be used to wean wolffish from live prey to pellet food. Using this information, improvements of the rearing protocols of these species may now be made.

Vitellogenin (VTG) from spotted wolffish, Anarhichas minor, a candidate species for cold-water marine aquaculture, was purified by MgCl2/EDTA precipitation followed by a two-step chromatographic procedure. VTG had an apparent molecular mass of 470 kDa, as determined by gel filtration, and an amino acid composition similar to those of other teleosts. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of the purified VTG revealed a major band with a relative molecular weight of 166 kDa and some minor bands. Spotted wolffish VTG (sw-VTG) is relatively robust to in vitro degradation, as shown when samples of purified VTG and plasma from mature females subjected to various storage conditions or multiple freeze/thaw cycles were analyzed by Western blot. We developed an indirect competitive enzyme-linked immunosorbent assay (ELISA) using an antibody against Atlantic wolffish (Anarhichas lupus) VTG and purified sw-VTG. The ELISA had a detection limit of 6.7 ng/ml and a working range of 16.2–787.5 ng/ml, with intra- and inter-assay coefficients of variation ranging from 1.5 to 7.3 % and 7.1 to 14.3 %, respectively. The assay could distinguish males from immature females and discriminate maturing females at different stage of oocyte development. These results suggest that the sw-VTG ELISA would be useful in spotted wolffish aquaculture to determine sex and monitor female maturation.

Phylogenetic analyses of all 4 wolffish species (Atlantic, Spotted, Northern, and Bering wolffishes) and the Wolfeel were assessed with both mitochondrial (D-loop and ND1) and nuclear (amplified fragment length polymorphism) DNA to resolve relationships within the family Anarhichadidae. Species-specific mitochondrial DNA (mtDNA) mutation rates were estimated based on 2 possible dates of divergence between the Pacific and Atlantic lineages. Phylogeographic patterns within each of the 3 North Atlantic wolffishes were investigated with Markov chain Monte Carlo simulations based on mtDNA to determine whether population size changes occurred following the last glaciation and where wolffishes likely survived glaciation. All 3 species of North Atlantic wolffishes showed evidence of postglacial expansion but did not show evidence of persistence in multiple refugia in both the eastern and western Atlantic Ocean. Rather, the data supported persistence in a single refuge, with postglacial expansion into the rest of the range. Nucleotide diversity, in particular, was low in wolffishes compared with other marine fishes, possibly related to reductions in population sizes during the last glaciation.

The spatial and temporal distribution patterns of the Atlantic wolffish (Anarhichas lupus) from the Gulf of Maine-Georges Bank region were examined based on bottom trawl survey data from 1963 to 1989. Age composition, growth and food habits were also evaluated from 1983 to 1989. Catches of wolffish were distributed throughout the region, but highest concentrations occurred along the 100 m depth contour of the Gulf of Maine-Georges Bank. Statistical analyses of the depth occurrences revealed a seasonal shift in depth distribution from shallow water ( 50 cm) wolffish migrate to these shallow waters in spring and return to deeper waters in autumn. The oldest wolffish aged was 22 years. Mean length-at-age ranged from 4.7 cm total length for age 0 to 98.0 cm total length for age 22 in spring. Growth was modelled best by the Gompertz function. Bivalve molluscs (primarily Placopecten magellanicus) dominated the diet, followed by echinoderms, gastropods and decapods. Introduction The Atlantic wolffish (Anarhichas lupus) is a commercially important, cold water species found on both sides of the North Atlantic. In the Northwest Atlantic, its distribution extends from off Greenland to the Nantucket Shoals off the eastern United States (Jonsson, 1982). It is typically captured incidental to fishing operations directed toward other benthic species in this region. Commercial landings in USA territorial waters are from the Gulf of Maine and Georges Bank (NAFO Subarea 5), where the total USA nominal catch increased from 200 tons in 1970 to 1 200 tons in 1983 and have since declined to 500 tons (NMFS/NEFC, 1991). Additionally, National Marine Fisheries Service (NMFS), Northeast Fisheries Center, Woods Hole, Massachusetts, bottom trawl surveys indicate a long-term decline in relative abundance since the 1970s (NMFS/NEFC, 1991). Such information suggests that the Atlantic wolffish population of the Gulf of Maine-Georges Bank may be overexploited. However, currently there is no fishery management plan implemented to control fishing mortality on this species. Data on population biology and dynamics of exploited species are essential for proper management strategies. Past research concerning the biology of the Atlantic wolffish has included studies on food habits (Jonsson, 1982; Albikovskaya, 1983; Templeman, 1985; Hawkins and Angus, 1986), distribution and migratory patterns (Albikovskaya, 1982; Jonsson, 1982; Templeman, 1984), reproductive behaviour (Keats et al., 1985), age and growth (Jonsson, 1982) and sexual maturity and fecundity (Templeman, 1986) from Icelandic to Nova Scotian waters. Only descriptive data on depth distribution, food habits and breeding habits (Bigelow and Schroeder, 1953) are available for fishes in United States territorial waters. This study was undertaken to document trends in spatial and temporal distribution patterns based on bottom trawl survey data, and to evaluate quantitatively age, growth and food habits of Atlantic wolffish from the Gulf of MaineGeorges Bank region. Materials and Methods Data used for the spatial and temporal distribution analyses were collected from 1963 to 1989 in the Gulf of Maine-Georges Bank region by NMFS in a synoptic bottom trawl survey. The survey was based on a stratified-random sampling design for continental shelf waters >27 m in depth, partitioned into strata of unequal area based on depth and geographic location (Grosslein, 1969; Azarovitz, 1981). Prior to 1968, sampling was conducted only in autumn. A spring survey was added to the annual schedule in 1968. Sampling effort was expanded in 1972 to include the nearshore waters between 5 and 27 m depth. Sampling during spring and autumn J. Northw. Atl. Fish. Sci., Vol. 13: 53–61 54 J. Northw. Atl. Fish. Sci., Vol. 13, 1992 occurred generally in March to May and September to November, respectively. Sampling stations were randomly selected within each stratum and effort (number of stations) allocated in rough proportion to stratum area. At each station, a # 36 or # 41 Yankee otter trawl with a 1.25 cm stretched mesh codend liner was towed at approximately 3.5 knots for 30 min; bottom depth and near-bottom temperature data were also recorded (Azarovitz, 1981). Changes in spatial distribution between spring and autumn were examined for the 1963–89 survey period. Depth of occurrences, weighted by the number of wolffish captured in each tow, were compared between seasons using Kruskal-Wallis nonparametric ANOVA (Gibbons, 1976). Further, length frequencies were examined by depth ranges for evidence of a seasonal reproductive migration noted by Keats et al. (1986). Due to the low numbers of wolffish captured annually, data from all survey years were combined for these analyses. Age and growth Wolffish were collected opportunistically for the age, growth and food habits analyses from autumn 1983 to spring 1989. Individuals captured in the otter trawl were weighed collectively to the nearest 0.1 kg, measured individually (total length; TL) to the nearest cm, and sexed. The head and entire digestive tract from the esophagus to rectal sphincter were then removed, stored in plastic bags, and frozen. Occasionally, small wolffish (

The predatory impact of the American lobster Homarus americanus and the Atlantic wolffish Anarhichas lupus on the green sea urchin Strongylocentrotus droebachiensis was investigated in a multifactorial experiment. Both predators exhibited either Type 2 or Type 3 functional responses to increasing prey density, but the magnitude of the response differed for the two predators, and for different prey sizes. Predation on large (>20 mm ) sea urchins increased approximately three-fold, i.e., from 1.12 to 3.54 urchins·day −1 for wolffish, and from 0.35 to 0.97 urchins·day −1 for lobster, when prey density was increased sixfold, i.e., from 5 to 30 urchins·tank −1 . Although more urchins were killed at the highest density, the proportion of available urchins that were killed dropped by ≈50%. Predation on small (⪯20m) sea urchins was similar for both predators, increasing from ≈0.5 to ≈1.9 urchins·day −1 with increased prey density. In the lobster treatment, a rock crab, Cancer irroratus Say, was included as alternative prey. The lobsters killed 5.78% of the total number of available rock crabs, and 5.01% of the total number of available urchins, but lobster predation on urchins was nearly halved in replicates where the crab was killed. Experimental factors other than prey density and prey size, i.e., season; availability of food and physical refuges for the prey, and whether the prey had been fed or starved prior to the experiment , had no significant effects on the predation rates of either predator. These results are consistent with the hypothesis that green sea urchin outbreaks may be triggered by reductions in predation pressure. There was no evidence of significantly increased predation on morbid sea urchins although ≈1% of the experimental sea urchin population exhibited symptoms of amoeboid, Paramoeba invadens (Jones), disease.

The effects of water temperature (5, 8, 11, and 14°C) on the fractional rate (percent per day) of protein consumption (kr) and on white muscle and whole-body fractional rates of protein synthesis (ks), protein growth (kg), and growth efficiency (PPV, growth/consumption; kg/ks, growth/synthesis) of juvenile Atlantic wolffish (Anarhichas lupus) (initial body weight 26 g) were studied. Rates of protein consumption and white muscle and whole-body protein synthesis increased in a linear fashion between 5 and 14°C. In contrast, the relationships between temperature and white muscle and whole-body protein growth, protein growth efficiency (PPV) and protein synthesis retention efficiency (kg/ks) were parabolic. The results indicated that the optimum water temperatures for growth (Topt.G) and growth efficiency (Topt.GE) were 10-11 and 9-10°C, respectively. The maximum white muscle and whole-body protein growth rates recorded at Topt.G were 0.9 and 0.7 %·day-1, respectively. At Topt.GE, the maximum white muscle and whole-body PPV values were 28 and 34%, respectively, and kg /ks values were 92 and 51%, respectively. The growth performance data for juvenile Atlantic wolffish in comparison with published data for salmonids (rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar)) at 9-11°C further highlight its suitability as an alternative species for cold-water aquaculture in northern Europe and Atlantic Canada.

At present, the severe decline of the fishery off Greenland is being discussed controversially. In contrast to overfishing, climate changes and emigration are itemized causal. Available German data on commercial catches and research cruises are presented for clarification. A few years after the beginning of heavy exploitation during the early sixties, the stocks of cod, golden and beaked redfish reflected a significant rejuvenescence based on catch analysis. Regular scientific surveys• for stock assessment purposes commenced in 1982 when the productivity of the stocks was already adversely affected due to low spawning stocks and extremely irregular recruitment. From this point of view, the results of the latest survey in 1995 showing stagnant fish biomass at record low level since 1991 are not surprising. The status of the cod stock is still considered severely depleted. Taking the high abundance of juvenile redfish into account, recovery of the groundfish stocks is unlikely in short term and depends on the non-predictable recruitment only. Johann Heinrich von Thünen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung = Information on Fishery research in 2010.

We have expressed two antifreeze protein genes from the Atlantic wolffish, Anarhichas lupus, in Drosophila melanogaster by placing them under the divergent transcriptional control of the host yolk poly-peptide (1 and 2) gene promoters. Both genes were joined to the central promoter region by fusion within the DNA encoding the signal polypeptides. The chimeric genes were introduced into flightless mutant Drosophila through P-element transformation. Transformed adult females from individual lines accumulated 1.5–5 mg/ml of antifreeze protein in their hemolymph. The protein was purified to homogeneity from hemolymph following thermal denaturation, step elution from SP-Sephadex, and reverse-phase HPLC. It was recovered in high yield and retained full biological activity even though one of the two gene fusions gave rise to a seven amino acid N-terminal extension on its antifreeze protein product.

From collections of Atlantic wolffish in the Northwest Atlantic (West Greenland to the Scotian Shelf) during 1950-67, mean vertebral counts increased gradually from the colder northern to the warmer southern areas (74.19 off Labrador to 75.29 on the southern Scotian Shelf). This is the reverse of the usual pattern in other fishes of the region with pelagic eggs. The pattern for mean dorsal fin-ray counts was similar, but the area coverage and sample sizes were less extensive and the differences were less significant than in the vertebral data. The overall ranges in counts were 72-78 for vertebrae and 71-77 for dorsal fin-rays. Dorsal fin-ray and vertebral numbers were moderately well correlated in a limited number of specimens.

The reproductive season, the sex that provides parental care, and the relationship of feeding with reproduction are reported for Atlantic wolffish and ocean pout in eastern Newfoundland. Both species move into shallow water in the spring, pair during the summer, and spawn in holes under and between boulders during the autumn. Apparently, male Atlantic wolffish provide solitary parental care of the eggs, while in ocean pout females provide this function. Feeding is reduced for females and probably males of both species as the gonads approach maximum size. After pair formation, male ocean pout reduce feeding; male Atlantic wolffish do so to a lesser degree. Male Atlantic wolffish and female ocean pout feed little or not at all while guarding egg masses.

Tagging of 398 Atlantic wolffish, Anarhichas lupus, 81 spotted wolffish, A. minor, and 101 northern wolffish, A. denticulatus, with Petersen disc tags in the Newfoundland area during 1962-66 yielded 5.0, 7.4 and 3.0% returns respectively. Recapture information indicates that migrations are generally short but some rather long migrations were noted. The rate of recapture of Atlantic wolfish declined rapidly from 15.4% for coastal taggings to 6.7% for offshore taggings except Flemish Cap and to 1.1% for Flemish Cap tagging. Depths of recapture of Atlantic wolffish ranged from 20 to 476 m. Fig. 1. Map of the study area with place names mentioned in the text. Materials and Methods Because of the lack of information on movements of wolffishes in eastern Canadian waters, some tagging of the three species off Newfoundland (Fig. 1) was carried out during 1962:66.

The diet of the Atlantic wolffish was studied by examining the contents of the gastrointestinal tracts of 90 individuals collected from the sea urchin dominated rocky subtidal in eastern Newfoundland. Green sea urchins comprised 75% of the overall diet by weight. Horse mussels ranked second but comprised only 9.5% of the diet. The remainder of the diet consisted of several species of invertebrates and fish. The average (over the whole season) wolffish contained 120 g of urchins, equivalent to the biomass of urchins on 0.23 m2 in the middle of the urchin-dominated zone. During April–September, prior to breeding, the average male wolffish contained 174 g of urchins, and the average female contained 85 g of urchins, biomass values representing, respectively, 0.33 and 0.16 m2. Assuming that the contents of the gastrointestinal tract turn over every 3 days, it was calculated that during May through August each wolffish consumes on average 5.29 kg of urchins (males, 7.09 kg; females, 3.50 kg). Based on these figures, a density of 1 wolffish pair per 20 m2 would be required to consume the mean biomass (532 g m−2) of urchins present in the urchin-dominated zone in 1 year.