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The spotted wolffish ( Anarhichas minor Olafsen) is a species of the Perciformes, the most diverse and numerous order of all fish. A cDNA library from head kidney tissue was screened for immunoglobulin (Ig) heavy and light chain transcripts, and showed highest identity to Ig sequences from other perciform species. So far only one Ig class is described in spotted wolffish, but three V H families were identified among the heavy chain transcripts. Highest diversity was located at the CDR3 region and demonstrates the importance of this gene element to the antibody repertoire. Two V L families were identified among the light chain clones and three distinct isotypes were present. Use of polymerase chain reaction and in situ hybridisation techniques revealed individual variations in the relative expression of the three isotypes of light chains.

The complement component C3 was isolated from spotted wolffish (Anarhichas minor Olafsen) serum by polyethylene glycol precipitation, anion exchange chromatography and gel filtration. Silver staining in SDS-PAGE and rabbit anti-wolffish C3 antiserum used in Western blotting revealed that spotted wolffish C3 contains two polypeptide chains, M(r)65 and 115kDa, respectively. The high molecular weight alpha-chain of the C3 incorporated 14C-methylamine suggesting that it contained a reactive thioester group. The deduced amino acid sequence, after screening a liver cDNA expression library, showed that the wolffish C3 contained key amino acids for binding C3 convertase, factor H, I and properdin. Also, high degree of homology to other vertebrate C3 was found in the beta-alpha junction site. Phylogenetic tree analysis indicated that the Japanese flounder and spotted wolffish that belong to order pleuronectiformes and perciformes, respectively, are phylogenetically close species. Immunohistochemical experiments showed that liver hepatocytes and blood contained C3, and in situ hybridisation experiments revealed that liver hepatocytes expressed C3.

To study the effect of early vaccination, wolffish juveniles of size 50 and 90 mm, respectively, were vaccinated with an oil-adjuvanted atypical A. salmonicida bacterin. Vaccination resulted in significant protection after challenge with the homologous bacterial strain and specific antibody responses were demonstrated against whole bacteria as well as purified A-layer protein and LPS by ELISA and Western blotting but individual variation in immune responses was apparent. The A-protein was the most immunogenic bacterial component. In addition, higher numbers of immunoglobulin producing cells were detected by in situ hybridisation in kidney and spleen of vaccinated fish compared to non-vaccinated fish. Plasma cells were also present in gut and gills in equal numbers irrespective of treatment. No plasma cells were found in the skin. Finally, the frequencies of expressed VHfamilies and CLisotypes of wolffish immunoglobulins were shown by PCR. The relative expression of the three variable regions of the Ig heavy chain and the three isotypes of the Ig light chain in the spotted wolffish spleen seemed to be unaffected by immunisation with a complex antigen like the A. salmonicida bacterin.

The cDNA clones encoding immunoglobulin (Ig) light (L) chain variable (V) region associated with constant (C) region were isolated from yellowtail (Seriola quinqueradiata) kidney by expressed sequence tag analysis (accession numbers: AB062619-AB062668, AB064322). The sequences of both VL and CL region contain well-conserved cysteine residues important for intra- and inter-domain interaction in mammals. Comparisons of the amino acid sequence of the CL domain with those of other species showed a high degree of similarity, with 88.3%, 59.8%, and 60.6% to those of wolf fish (Anarhichas lupus), rainbow trout IgL I isotype (Oncorhynchus mykiss) and channel catfish G isotype (Ictalurus punctatus), respectively. Multiple sequence alignments of the CL domain with those of higher vertebrates, however, did not readily allow it to be classified as kappa or lambda isotypes. Furthermore, the pI, hydrophobicity and variability of yellowtail VL regions were studied in 65 cDNA clones and the diversity was observed in CDR1, CDR2 and CDR3 regions.

The Arctic fish Anarhichas minor, a benthic sedentary species, displays high hemoglobin multiplicity. The three major hemoglobins (Hb 1, Hb 2, and Hb 3) show important functional differences in pH and organophosphate regulation, subunit cooperativity, and response of oxygen binding to temperature. Hb 1 and Hb 2 display a low, effector-enhanced Bohr effect and no Root effect. In contrast, Hb 3 displays pronounced Bohr and Root effects, accompanied by strong organophosphate regulation. Hb 1 has the beta (beta(1)) chain in common with Hb 2; Hb 3 and Hb 2 share the alpha (alpha(2)) chain. The amino acid sequences have been established. Several substitutions in crucial positions were observed, such as Cys in place of C-terminal His in the beta(1) chain of Hb 1 and Hb 2. In Hb 3, Val E11 of the beta(2) chain is replaced by Ile. Homology modeling revealed an unusual structure of the Hb 3 binding site of inositol hexakisphoshate. Phylogenetic analysis indicated that only Hb 2 displays higher overall similarity with the major Antarctic hemoglobins. The oxygen transport system of A. minor differs remarkably from those of Antarctic Notothenioidei, indicating distinct evolutionary pathways in the regulatory mechanisms of the fish respiratory system in the two polar environments.

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.

The transition from the larva state to the juvenile state (i.e. morphological condition characterised by mainly adult characters) was examined in three marine fish species: herring Clupea pallasi marisalbi, wolffish Anarhichas lupus, and eelpout Zoarces viviparus, based on external morphology and skeletal development. In spite of the different reproductive styles (oviparity, facultative viviparity, and obligate viviparity, respectively) and different types of early ontogeny (indirect, transitory, and direct, respectively), the beginning of the juvenile state occurred at similar total lengths (TL), which were approximated as 35 mm TL in herring and eelpout, and 32 mm TL in wolffish. Features of ontogeny were compared, assuming that the beginning of the juvenile state represented an uniform characteristic of morphological development for these species. It was proposed that the beginning of the larva or juvenile periods (sensu Balon) could not coincide with the beginning of the larva and juvenile states in the ontogeny of some species.

Incubation of follicular cells from postvitellogenic spotted wolffish ovaries with tritiated steroid precursors revealed that granulosa cells were able to convert 17-hydroxyprogesterone (17-P) to 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) and androstenedione. Theca cells had limited ability to synthesise additional steroids from 17-P but converted 17,20β-P to 17,20β-P sulphate. Neither of the two cell layers was able to synthesise 5β-pregnane-3α,17,20β-triol-20-sulphate (3α,17,20β-P-5β-S) which is found in high concentrations in plasma. 17,20β,21-trihydroxy-4-pregnen-3-one (17,20β,21-P), 17,20β-dihydroxy-5β-pregnan-3-one (17,20β-P-5β) and 17,20β-P were most potent in inducing germinal vesicle breakdown (GVBD). Sulphation of 17,20β-P resulted in loss of GVBD inducing activity.

Peculiarities of reproduction, early ontogeny, methods of egg incubation, and influence of temperature on development are compared in wolffish (Anarhichas lupus L.) and in salmonids, mainly Atlantic salmon (Salmo salar L.). Reproductive indices of females are similar in both species, but differ in males due to the small production of sperm in wolffish, a difference explained by internal fertilization in the latter species. The rate of embryonal development until the beginning of differentiation of fin fold at the same temperature is similar in both species, but the period from activation to hatching is more than twice as long in wolffish as in Atlantic salmon. Wolffish hatch at a more advanced stage with a small remnant of yolk sac and begin to feed shortly thereafter. As in Atlantic salmon, eggs and larvae of wolffish have a wide range of temperature resistance except before and after hatching. Based on the difference of life cycles in wolffish and salmon, technologies for their artificial breeding are compared.

The diet of common wolffish Anarhichas lupus from the North Sea is described, from a total of 143 wolffish stomachs, of which 112 contained food. The main prey were crustaceans and molluscs, together representing almost 70% of diet by relative frequency of occurrence in stomachs. Wolffish >55 cm preferred polychaetes and gastropods while wolffish

Three groups of newly hatched wolffish larvae (one group in the Faeroe Islands and two groups in Norway) were start-fed on commercial dry pellets. Survival rates were between 10.5 and 53.7% during the first 108 days after hatching. The specific growth rate varied between 2.00 and 3.34%/day in the same period. A high mortality was observed between 20 and 40 days after hatching. A maximum specific growth rate (3.0–3.6) was observed 100–150 days after hatching, followed by a decrease to 0.4 and 0.8 at the end of the experiment. High mortality was observed in one of the groups during the juvenile stage, caused by heavy infection by the ectoparasite Trichodina sp. The behaviour of both larvae and juveniles was studied. The larvae spent most time in midwater while juveniles were most active around feeding time and spend most of the day lying on the bottom of the tanks. Cannibalism was observed occasionally and only among larval fishes. No cannibalism was observed in the Faeroe Island fish which were continually fed at 10 min intervals throughout 24 h.

A piroplasm, Haemohormidium beckeri, is redescribed from two marine fish, Lycodes lavalaei and Lycodes vahlii (Zoarcidae). The parasite divided by both binary fission and schizogony. In the latter process, up to eight merozoites were produced and these developed within mature erythrocytes. Infections were prevalent among fish from areas off the Labrador coast. Parasitemias, which varied from light infections to estimates of 60 parasites/1000 erythrocytes, were recorded in 15 fish for about 6 months. Subinoculation of infected blood initiated infections in two perciform fish, Myoxocephalus octodecemspinosus and Anarhichas lupus, but not in a pleuronectiform, Pseudopleuronectes americanus, or a gadiform, Gadus morhua. Natural infections were present in three leeches, Platybdella olriki, that had fed on an infected L. lavalaei. Piroplasms were also observed in the gastrointestinal content of all 94 laboratory-reared leeches, Johanssonia arctica, dissected 7 through 109 days after engorgement on infected fish blood. Inoculations of gut contents from leeches after digestion of a blood meal produced infections in uninfected fish. Natural transmission occurred when leeches were fed again on susceptible fish, whereas pipetting entire leeches into the stomach of fish did not initiate infections. This is the first evidence that leeches transmit piroplasms in nature to fish.

The potential of employing ultrasonic waves to detect sealworms embedded deep in the fish musculature was demonstrated. Images were made of sealworm-infested cod by using both the scanning laser acoustic microscopic technique, as well as the pulse-echo technique at 10 MHz. Also, attenuation of ultrasound in the frequency range from 1.0 to 12.25 MHz was studied in Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), ocean catfish (Anarhichas lupus), and the parasitic sealworm (Phocanema decipiens). The difference in the attenuation of ultrasound in sealworms and in fish tissue increased as a function of frequency. The differences between ultrasonic properties (attenuation and backscatter) of fish tissue and seal-worms was attributable to the high collagen content of the sealworms. The differences were sufficiently large at 10 MHz that sealworms could be detected in over 4 cm thickness of fish tissue.

Lead concentrations in spotted wolffish (Anarhichas minor) collected from the vicinity of a sphalerite–galena mine and an ore concentration plant in West Greenland have been measured through a period of 2 yr before and 4 yr after mining operations started. Lead levels increased significantly since mining started, and accumulation takes place in liver and kidney, not in muscle tissue. The increased lead levels are not a risk to public health. Small fish have higher lead concentrations than larger ones. Key words: wolffish, arctic, liver, muscle, kidney, lead, zinc–lead mining

Hatching of wolf fish eggs under artificial conditions was dependent upon a continuous supply of clean (not sterile) oxygen-rich sea water. Eggs older than 700 degree-days could be induced to hatch by applying mechanical stress. During embryonic development egg lipid level decreased gradually, but the proportions of fatty acids and amino acids remained relatively unchanged. The fatty acids were dominated by 16:0, 18:1 and the ω3 PUFAs 20:5 and 22:6. The fry were fed three different start-feeds: cod (Gadus morhua L.) roe diet, Acartia longiremis, or Metridia longa. The cod roe diet did not support growth of the fry beyond 50 days, but fry fed natural zooplankton continued to grow beyond 120 days.

The dental system and teeth morphology of Anarhichas lupus L. are perfectly suited to its mode of feeding. The anterior teeth are used for grasping preys. The molariform lateral and posterior teeth, palatine and vomer, are used for crushing ingested organisms with hard shells such as gasteropods and lamellibranchs. Microradiography gives evidence of the high degree of mineralization of enameloid and osteodentine trabecules. The supporting bone is constituted of two parts: a basal bone, with a low degree of mineralization, and a proper bone, highly mineralized, with large medullar canals. The structure of the basal bone, closely connected with the proper bone, accounts for the resilience of the whole system.

The time trend in the DDT contamination of the marine environment in a Norwegian fjord where DDT has been used extensively in local fruitgrowing, has been studied for 10 years following the DDT ban. Residues of ∑-DDT (p,p′-DDT + 1.11p,p′-DDE + 1.11p,p′-TDE (DDD). The factor 1.11 is added to correct for the lower molecular weight) in 225 liver samples of seven sedentary fish species showed a downward trend during the period 1972 to 1982. The decrease in ∑-DDT illustrates the effectiveness of the 1970 ban on its use in Norway. The highest 1982 mean level of ∑-DDT was found in the liver of cod (Gadus morhua) (1237 μg/kg, wet weight, range 191–3845 μg/kg) and was about 1/3 of the corresponding 1972 residue level. The decrease of ∑-DDT was less rapid in the liver of the cod and the haddock (Melanogrammus aeglefinus) (half-life time 5.0 years with a 95% confidence limit of 2.3 years) than in the fish species sea scorpion (Myoxocephalus scorpius), cat fish (Anarhichas lupus), ballan wrasse (Labrus berggylta) and lemon sole (Microstomus kitt) (half-life time 2.6 years with a 95% confidence limit of 0.8 years). Cod and haddock have a substantially higher fat content in the liver compared to the other fish species. A half-life time of 3–5 years for biologically available DDT residues is suggested to apply generally to Nordic marine environments. Unmetabolized DDT constitute a smaller proportion of ∑-DDT in 1982 than in the previous years. However, a great variation between species and individuals was found. PCB contamination in the fish was low, and reflect a Norwegian baseline contamination. The highest 1982 mean level of PCB residues was found in cod liver (454 μg/kg, wet weight, range 175–1073 μg/kg) which was about 1/3 of the 1972 value. The levels of ∑-DDT and PCBs were correlated to fish weight in the cod. These two types of residues were mutually correlated over all weights. No correlation was found between the fat content of the liver and the residue level of organochlorine chemicals within the species. Only low levels of contamination by hexachlorobenzene (HCB), α-, γ-HCH and ∑-chlordane were found in 1982. The highest levels were found in cod liver (HCB 6–26; γ-HCH 6–16; α-HCH 4–140;∑-chlordane = oxychlordane + transnonachlor 38–220 μg/kg, wet weight). The levels of organochlorines in fish from a Norwegian fjord were generally low and not believed to have any toxicological implications.

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.

TEM, SEM and X-ray diffraction analysis demonstrate the heterogeneity of the dentinal tissue on Anarhichas lupus, a vascular osteodentine. The disordered aspect of collagen fibres, incompletely mineralized (the periodical striation being still visible), explains the scattered distribution of crystallites since they are responsible for their arrangement. The low degree of mineralization revealed by the visible collagen striation is confirmed by X-ray diffraction analysis (the crystallinity of vascular osteodentine being much lower than that of the peripheral dental tissue) as well as by high resolution TEM, since no lattice planes could be observed. Osteodentine, supporting bone and proper bone have in common a mineral phase, more or less organized, different from the apatite system.

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.

Highlights • A novel myxosporean species, Kudoa islandica, is described. • It is prevalent in lumpfish and Atlantic and spotted wolffish. • It causes extensive post mortem myoliquefaction. • It was a major factor in the closure of spotted wolffish farming in Iceland. • It infects fish from different taxonomic orders and could be a concern in aquaculture., In the early 2000s, experimental rearing of spotted wolffish, Anarhichas minor, was started in Iceland. Health surveillance, carried out at regular intervals during the rearing period, revealed persistent and highly prevalent Kudoa infections of fish muscles which caused great financial losses due to post mortem myoliquefaction. In addition, during the traditional process of drying and smoking wild Atlantic lumpfish, Cyclopterus lumpus, the muscles from some fish almost completely disappear and the fish have to be discarded. To describe the etiological agent responsible for these conditions, spotted wolffish, Atlantic wolffish Anarhichas lupus, northern wolffish Anarhichas denticulatus and Atlantic lumpfish were caught off the Icelandic coast and examined for the presence of Kudoa. We describe a novel myxosporean, Kudoa islandica n. sp., using morphological and molecular data, and show with histopathology that it causes extensive myoliquefaction in three different wild fish hosts, which all are commercially valuable species in Iceland. Although some spore dimensions varied significantly between fish species, the molecular analyses showed that the same parasite was responsible for infection in all fish. The northern wolffish was not found to be infected. Although robustly placed in the Kudoa clade in phylogenetic analyses, K. islandica was phylogenetically distinct from other kudoids. A single myxosporean, K. islandica, is responsible for the infections in the somatic muscles of lumpfish and wolffish, causing extensive post mortem myoliquefaction. This myxosporean is likely to infect other fish species and it is important to study its life cycle in order to evaluate any threat to salmonid culture via the use of lumpfish as a biocontrol for sea lice.

The wolf fish (Anarhichas lupus L.) has considerable potential for aquaculture. This note describes brood protection by the fish as observed in the aquarium in Tromso, Northern Norway.

Three specimens of Anarhichas lupus L. with teeth presenting burrowing lesions were studied with light microscopy, SEM, and high resolution TEM. Findings suggested that the lesions were due to fungoid invasion by Mycelites ossifragus . The burrowing lesions always originated in the more highly mineralized external tooth layer, thus distinguishing them from post-mortem soil changes which may start in any part of the tooth. The channels produced by the lesion had no particular orientation to the dentinal vascular canals. It is suggested that enzymes are secreted locally by the causal organism; burrows were thus not found at a distance from the fungus whose numerous microvilli were in close contact with the mineralized walls of the channels; this distinguishes the lesion from dental caries. Needle-shaped crystals are found within the cytoplasm or adherent to the plasma membrane of the burrowing organism. Other crystals in the immediate neighbourhood of the organism were hollow, and thus suggestive of an organism feeding on mineral material. Bacterial invasion was sometimes in association with the burrowing activity, and may play a part in it, but often appeared to be a later invasion.

Anarhichas [gen. nov.] Caput obtusiusculum. Dentes confertissimi, rotundati: antici VI, conici. Membr. branch. rad. VI. Corpus teretiusculum. Pinna caudae distincta., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 247, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Anarhichas lupus [spec. nov.] Anarhicas. Art. gen. 23. syn. 38. Gron. mus. 1. n. 44. Anarhicas. @/D. 73. P. 20. V. 0. A. 45. C. 18. Habitat in Oceano septentrionali Angliae, &c. Lapis Bufonites ex bujus piscis dente., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 247, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

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