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To understand and clarify the geographic variations of the Korean sea raven, Hemitripterus villosus, we investigated the molecular and morphometric characteristics of 147 individuals (in morphs) and 175 individuals (in molecules) collected from three locations in the Yellow Sea (Incheon, Boryeong, and Heuksando), one location in the Korea Strait (Busan), and two locations in the East Sea (Goseong and Pohang), around the Korean peninsula. The Kruskal-Wallis test showed there were no significant differences in meristic characteristics among locations, except for the number of vertebrae (mean, 39.7 in Goseong vs. and 38.4–38.8 in the remaining locations). A canonical discriminant analysis based on 25 morphometric characters showed that two groups were separated by the center value “0” of CAN1: Yellow Sea and Korea Strait individuals had positive values, whereas East Sea individuals had negative values. An analysis of molecular variance (AMOVA) based on 801 base-pair sequences of the mitochondrial DNA cytochrome b gene showed that two lineages were separated by fixation (FST) index. A pairwise FST test revealed moderate genetic differentiation between the Goseong individuals (middle East Sea) and the individuals at the remaining locations except for the Pohang individuals (southern East Sea). Our molecular and morphometric analysis results indicate that there exists two populations in the Korean sea raven, and their admixture zone may be located near Pohang. Population subdivision might be associated with sea level change during last glacial period, and this may have been subsequently maintained by the hydrographic and oceanic current heterogeneity of each sea around the Korean peninsula. Accordingly, different management measures should be adopted with regard to the two groups, the East Sea group and the Yellow Sea + Korea Strait group.

The reproduction period of the sea raven Hemitripterus villosus were studied by visual SCUBA-diving methods in 1997–2016 in Peter the Great Bay, the Sea of Japan. It has been found that the beginning and the end of the spawning period shifted to a later date (5–12-day shift) in particular years, which is explained by the increased water temperature at the spawning grounds by 1.6–2.5°C in September–October. The degree of damage of the open egg masses has greatly increased (from 35.2 to 60.4%), the main predator is the sea urchin Mesocentrotus nudus. The observed changes in the timing of reproduction and an increase in the degree of egg consumption by predators are not critical factors for reducing the abundance of the sea raven.

article i nfo The American lobster, Homarus americanus, is an important benthic consumer in the Gulf of Maine and supports anextremely valuable fishery in New England and eastern Canada. Meanwhile, there issubstantial interest in re- storing large predator fish species to the Gulf of Maine, and these predators may impact lobster populations both by consuming them and by inducing them to alter their behavior. Lobster tethering experiments were used to examine the susceptibility of a range of lobster size classes to predation in Saco Bay, Maine. The most susceptible sizes of lobsters were then exposed to three different fish predators (Atlantic striped bass Morone saxatilis, Atlantic cod Gadus morhua ,a nd sea ravenHemitripterus americanus) separately in experimental mesocosm tanks. Juvenile lobsters moved less and spent more time in shelter when in the presence of cod or sea raven. By contrast, striped bass did not induce lobsters to alter their behavior. Striped bass are highly mobile, active pursuit predators, which are thought to induce weaker behavioral responses in prey than sit-and-pursue predators like sea ravens. Thus, differences in lobster sheltering behavior corresponded with differences in predator foraging behavior. These predator-induced changes in behavior can result in less foraging activity, which may translate into reduced lobster growth and reproduction. Efforts to model marine communities and ecosystems will benefi tf rom am ore holistic understanding of whether predators induced prey to modify their foraging behavior and habitat usage.

Feeding and trophic relationships have been studied for the common benthic predatory fish species of the West Kamchatka shelf in 2008—the Pacific cod Gadus macrocephalus, great sculpin Myoxocephalus polyacanthocephalus, plain sculpin M. jaok, sea raven Hemitripterus villosus, and whitespotted greenling Hexagrammos stelleri. Crustaceans and fish are the main food components of the great sculpin, plain sculpin, Pacific cod, and whitespotted greenling; sea raven feeds on the fish mostly. The ontogenetic changes of the food spectra have been tracked for all the studied species. The indexes of the food similarity evidence to the possible food competition between the Pacific cod and all the other species; however, the dissimilarity of the ecological niches may serve as the adaptation to decrease the food competition. The trophic levels of all the studied predators vary from 3.41–4.50; i.e., they are the tertiary consumers. It is justified that the Pacific cod, whitespotted greenling, plain sculpin, and great sculpin are the facultative polyphagous predators, and the sea raven is the obligate bentho- and ichthyophagous species on the West Kamchatka shelf.

Although the number of marine protected areas (MPAs) for stock management has increased, movements or differences in population structure of a target species between an MPA and surrounding fishing areas have rarely been considered in stock biomass estimations. We developed a surplus production model considering seasonal movements between two areas; the model was applied to Sea Ravens Hemitripterus villosus off Fukushima, where almost all fishing has been prohibited since the 2011 accident at the Fukushima Dai-ichi Nuclear Power Plant. We predicted future biomass by using CPUE data from coastal gill-net fishing and offshore bottom trawl fishing in 2000 to 2009. The model reflected the seasonal coastal–offshore movements of Sea Ravens well, and it predicted increasing Sea Raven biomass in both areas, which was validated by the CPUEs observed after 2010—including those for trial bottom trawl fishing that occurred within limited offshore areas after the accident. Our results indicate that the newly de...

For the period 1999–2003, diet composition, diet similarity, and major predator–prey interactions between the 15 most abundant demersal and pelagic fishes (N = 12,163 stomachs) were described for Northumberland Strait - a semienclosed, marine, coastal ecosystem. Of the five pelagic species, Rainbow Smelt Osmerus mordax ate benthic prey (shrimps and polychaetes), Atlantic Herring Clupea harengus and American Shad Alosa sapidissima consumed small copepods and crab zoea, and Atlantic Mackerel Scomber scombrus and Alewife A. pseudoharengus ate small copepods and moderate amounts of benthic prey and small fishes. Three demersal species were strongly piscivorous but with minimal diet overlap: Sea Raven Hemitripterus americanus consumed small benthic fishes (especially flounders); Winter Skate Leucoraja ocellatus consumed sand lance (Ammodytes sp.) and Rainbow Smelt; and White Hake Urophycis tenuis consumed Atlantic Herring and Atlantic Mackerel. Cluster analysis revealed seven feeding guilds of which fo...

To estimate the mesh selectivity of gillnet for ocellate spot skate (Okamejei kenojei), the field tests were carried out 12 times with six different mesh sizes (121.2mm, 137.7mm, 151.5mm, 168.3mm, 178.2mm, 189.4mm) in the coastal waters of Taean, Chungcheongnamdo of Korea, 2010~2011. In the field tests, the total number of species was 31, and that of catch was 1,410 and the total weight was 618,006g. The number and weight of ocellate spot skate which is main target in this study were 1,004 and 434,592g, respectively. The catch in number of ocellate spot skate occupied about 71.2% in total catch. The others of catch species were marbled sole (8.4%), sea raven (4.4%), japanese swimming crab (4.2%) and flatfish (4.1%) and so on. The range of body disk width (DW) of ocellate spot skates which were caught in this study was 15.2~35cm and the mode was 27~29cm. The estimation equation of mesh selectivity using the extended Kitahara`s method was expressed as s $(R)

Two species of demersal fish, Liparis tessellates (cubed snailfish) and Hemitripterus villosus (shaggy sea raven), were investigated in relation to seasonal chemical composition. Total fat contents of the two fish were very low and were not appreciably different throughout the year, whereas their fatty acid compositions were significantly different depending on season. Noticeable changes in the moisture and protein contents in the two fishes were observed before and after spawning. Cubed snailfish showed relatively high amounts of total amino acids and free amino acids during summer months, whereas the levels of those in shaggy sea raven remained relatively unchanged throughout the year. Regardless of season, the major fatty acid of the two fishes was palmitic acid and most of polyunsaturated fatty acids (PUFAs) were n-3 PUFAs. Lead was over the legislative limit in some samples of the two fishes.

On the basis of long-term (1981–2008) observations, it was shown that, in the northwestern part of the Sea of Japan, sea raven Hemitripterus villosus is a common species with low, but stable numbers and it is a part of elittoral ichthyocenoses. During the year it performs wintering, feeding, and spawning migrations within the shelf and the upper part of the continental slope occurring from almost the water’s edge to a depth of 550 m. Highest density of sea raven is observed in Peter the Great Bay and the lowest is observed off the coasts of northern Primorye. Maximum length of H. villosus in the northwestern part of the Sea of Japan reaches 57 cm, and the modal group of fish consists of fish with a length of 25–45 cm (75%). In Peter the Great Bay, in the summer period, individuals with a length of 11–50 cm feed mainly on mass fish species; the value of daily ration of H. villosus varies from 1.6 to 3.2% of body weight, averaging 2.5%. According to an expert estimate, the biomass of sea raven in the northwestern part of the Sea of Japan reaches 2000 t.

Data on the spatial-bathymetric distribution and the size-weight composition of the sea raven Hemitripterus villosus in Pacific waters off the northern Kuril Islands and southeastern Kamchatka are provided. This representative of the family Hemitripteridae is a comparatively scarce, large fish species (maximum length 75 cm, body weight 11.8 kg), which in the study period (1992–2002) was found practically everywhere at the site from 48°00′ to 52°00′ N in the depth interval of 83–496 m at near-bottom temperatures from −1.2 to 3.5°C. However, during the year, the overwhelming majority of its individuals were recorded in two depth ranges—101–150 and 251–400 m, which is accounted for by seasonal changes in the habitation depths. With an increase in depth, the sizes of H. villosus increase in catches due to the fact that individuals with a body weight smaller than 1.7–1.9 kg reside mainly at depths of up to 300 m, and those with a body weight greater than 2.2–3.0 kg reside at larger depths. It is demonstrated that the occurrence and the amount of catches of H. villosus are subjected to some interannual, seasonal, and diurnal dynamics.

An experimental artificial reef (AR) was built in Peter the Great Bay (Sea of Japan) to compensate for the biotope of Zostera destroyed by sea urchins. After eight years, the number of fish species on the AR increased from 5 to 18 and the fish biomass increased from 3.07 up to 37.1 g/m2. Nonmigrating species (Opisthocentrus, young-of-the-year rockfishes, elegant sculpin) formed the bulk of the population; and migrant species (flounders, frog and great sculpins, sea raven) made up the greater portion of the biomass (up to 34 g/m2). Cage reefs are recommended to compensate for destroyed habitats, particularly Zostera beds.

Antifreeze proteins/polypeptides (AFPs), which are found in diverse species of marine fish, are grouped into four distinct classes (types I-IV). The discovery of skin-specific type I AFPs established that this class contains distinct isoforms, liver-type and skin-type, which are encoded by separate gene families. In this study, type I AFPs were isolated and partially characterized from skin tissues of Atlantic snailfish (Liparis atlanticus) and cunner (Tautogolabrus adspersus). Interestingly, evidence from this study indicates that snailfish type I AFPs synthesized in skin tissues are identical to those circulating in their blood plasma. Furthermore, type II AFPs that are identical to those expressed in liver for export into blood were purified from sea raven (Hemitripterus americanus) skin tissue extracts. It is clear that epithelial tissues are an important source for antifreeze expression to enhance the complement of AFPs that protect fish from freezing in extreme cold environments. In addition, the evidence generated in this study demonstrates that expression of AFPs in fish skin is a widespread phenomenon that is not limited to type I proteins.

The frequency and geographic distribution of trawlnet hangs from a fishery-independent survey are evaluated. The hangs data were plotted on a substratum map to confirm that many, but not all, were naturally occurring, high relief substrata. The data were also coupled with the occurrence of juvenile cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to assess the degree of association between juvenile gadoids and high relief substrata. The average minimal distance from a fish occurrence to a hang ranged from 8.1 to 12.0 km (4.4–6.5 nautical miles), well within the reported daily range of movement for these fish. A similar pattern was detected for the sea raven (Hemitripterus americanus), a predator of juvenile gadoids, confirming the location of these microhabitat foodwebs. On average, closing an area 3.7 km (2 nautical miles) around a hang will enclose 17–30% of the populations of these juvenile fish; a wider buffer (18–28 km; 10–15 nautical miles) will close a linearly increasing portion of the populations. Additionally, closing areas surrounding the hangs, particularly regions of high hang density, will help to minimize losses of or damage to fishing gear. We propose a win–win scenario by establishing or evaluating closed areas in regions with high concentrations of known hangs. This approach is widely applicable for many marine ecosystems and may help to achieve simultaneous conservation and resource management goals, whereby one can both protect pre-recruit fish and enhance the effectiveness of a fishery. Published by Elsevier Ltd on behalf of International Council for the Exploration of the Sea.

The function of myoglobin at the cellular level was investigated by comparing O2 consumption in isolated myoglobin-rich cardiac myocytes from the sea raven (Hemitripterus americanus) and myoglobin-poor myocytes from the ocean pout (Macrozoarces americanus). O2 consumption by sea raven myocytes, 0.21 +/- 0.04 microM O2/10(6) cells.min-1, was significantly higher than O2 consumption by ocean pout myocytes, 0.10 +/- 0.07 microM O2/10(6) cells.min-1 at high PO2. O2 consumption in sea raven myocytes treated with sodium nitrite was not significantly different than that in untreated myocytes at high PO2, but it was significantly lower than controls at low PO2. O2 consumption of sea raven myocytes treated with the mitochondrial uncoupler CCCP was not significantly different from that of control myocytes at high PO2, but it was significantly greater than untreated controls at low PO2. In ocean pout preparations, O2 consumption by nitrite-treated myocytes was significantly higher than that of untreated myocytes at high PO2, but it was not different from that of controls at low PO2. CCCP-treated ocean pout myocytes had a significantly higher oxygen consumption than that of untreated myocytes at high PO2, but oxygen consumption was not different from that of controls at low PO2. The CCCP-activated O2 consumption at low PO2 was myoglobin-dependent in that CCCP alone resulted in a threefold increase in sea raven cells over controls but had no impact on sea raven cells in the presence of nitrite or ocean pout cells treated with CCCP alone. This study further supports the contention that myoglobin only plays an important role in oxygen metabolism at low extracellular PO2's.

Certain plants, insects, and fish living in cold environments prevent tissue damage due to freezing by producing antifreeze proteins or antifreeze glycoproteins that inhibit ice growth below the normal equilibrium freezing point of water in a noncolligative fashion. In polar fish these macromolecules, taking into account their structural characteristics, are grouped into three broad classes, namely Type I, Type II, and Type III. In this paper we report the results of our studies on the stereospecific binding of sea raven, a Type II antifreeze protein (AFP) to (111) hexagonal bipyramidal faces of ice. Earlier studies of Type I and Type III AFPs have shown that stereospecific binding of these proteins, recognizing specific planes of ice, is essential for their noncolligative antifreeze point depression. Moreover, as it has been shown for the AFT of Type I, this binding also occurs along specific vectors on these planes and also is enantioselective, distinguishing between the mirror related directions. In this study we will show, by using molecular modeling, that the fold of Type II AFP could facilitate a stereospecific mode of interaction with (111) planes of ice. Similar to Type I AFP, preferential directionality of binding was also observed in the simulations.

Experimental data on photoreceptor cells and visual pigments are the basis for model calculations performed to assess photoreceptor quantum catches under disparate irradiance conditions. Three unrelated species of fish--black sea bass (Centropristis striata), sea raven (Hemitripterus americanus), and adult winter flounder (Pseudopleuronectes americanus)--are considered. In each case, receptor type quantum catches are compared for various water types and depths. By associating the habit and habitat of an organism with the physical properties of its photoreceptors, quantum-catch ratios are found as possible criteria in the selection of pigment peaks (lambda max). In addition to integrated ("total") quantum catches by the receptor types, rates of quantum catches are determined as a function of wavelength. The latter functions are replotted as pairwise difference spectra. These, in turn, are used to assess the ability of receptor types to participate in wavelength discrimination.

The objective of the study was to examine the physiological response to stress in a marine species with a sluggish life-style. The sea raven (Hemitripterus americanus), a marine benthic predator, did not produce elevated catecholamine levels when handled for blood removal, which facilitated repeated blood sampling from the same fish without cannulation. However, this species did release catecholamines in response to an acute stress (1 min of air exposure followed by 1 min of chasing), suggesting a high threshold (degree of external stimulation) for catecholamine release in this species. Plasma cortisol concentration increased significantly only after 1 h and remained elevated 4 h post-stress, showing a delayed response compared with salmonids. Plasma glucose concentration increased significantly at 0.5 h post-stress and remained elevated even at 24 h, while lactate levels dropped between 4 and 24 h post-stress. The delayed cortisol increase may not be due to altered plasma clearance, as no change in the plasma disappearance or tissue uptake of cortisol-derived radioactivity occurred with confinement stress in this species. Also, confinement stress did not alter the plasma disappearance or tissue uptake of radioactivity derived from glucose, indicating a higher production of glucose during stress. Food deprivation significantly increased the plasma disappearance and tissue uptake of both cortisol- and glucose-derived radioactivity in the sea raven. These results indicate that the hormonal response to stress in the sea raven is different from that of salmonids. This altered response may be an adaptation to prevent excess energy mobilization in a species with an inactive life-style and low metabolic activity.

The sea raven, Hemitripterus villosus, deposits its eggs on polychaete tubes (Salmacina sp.) in the coastal waters of Usujiri, southern Hokkaido, Japan. This is contradictory to investigations in the Bay of Peter the Great, Soviet Union, where eggs are deposited in narrow clefts. The egg masses are found among the bunchy worm tubes or between the base of the colony and the substrate. The spawning habit of H. villosus is distinct from ‘spawner in live invertebrates’ such as the little dragon sculpin Blepsias cirrhosus, which specifically associates with a sponge. That of H. villosus is classified as a ‘cavity spawner’.

The presence of fish antifreeze protein (AFP) mRNA was examined in a variety of tissues from the winter flounder (Pseudopleuronectes americanus), sea raven (Hemitripterus americanus), and ocean pout (Macrozoarces americanus), each of which contains one of the three known AFP types. Northern blot analysis indicates that whereas the AFP mRNA is restricted to liver in sea raven (type II AFP), significant amounts of mRNA are present in many other tissues in both winter flounder (type I) and ocean pout (type III). These results indicate that in sea raven, antifreeze protein synthesis only occurs in the liver, whereas in the ocean pout and winter flounder, synthesis occurs in many tissues throughout the body. These investigations are relevant to understanding the mode of action of these polypeptides.

The spawning habits of the sea ravenHemitripterus villosus were investigated by scuba diving at shallow rocky bottom sites around Bolshoi Pelis Island (Peter the Great Bay, Sea of Japan). Spawning occurs in September, when the surface water temperature drops. The optimum spawning temperature is 17–18°C. The fish density in nest sites reaches 120/300 m2. The mean individual fecundity is about 10000 eggs. Over 35% of the egg masses ofH. villosus are eaten by echinoderms, primarilyPatiria pectinifera andStrongylocentrotus nudus. Since fecundity is relatively low and parents do not take care of the egg masses, predation can strongly affect the abundance of this species.

Isoelectric focusing (IEF) was performed on soluble protein extracts from whole specimens of third-stage larval sealworm (Pseudoterranova decipiens) recovered from the musculature of three fish intermediate host species: Atlantic cod (Gadus morhua), sea raven (Hemitripterus americanus), and rainbow smelt (Osmerus mordax). The fish were collected at various sites in the Canadian Atlantic, and IEF revealed the occurrence of two "variants" within what has previously been considered a single, uniform species of P. decipiens in these waters. The larvae were characterized by the absence ("type I" L3's) or presence ("type II" L3's) of a sharp, dark-staining protein band with a mean pl of 6.46 pH units. Type I larvae were predominant at two sites sampled in the lower Bay of Fundy, while type II larvae were predominant at three sites sampled in the Gulf of St. Lawrence region.

Antifreeze proteins (AFPs) from smelt (Osmerus mordax) and Atlantic herring (Clupea harengus harengus) were isolated using gel filtration, ion exchange chromatography, and high performance liquid chromatography. The AFPs of smelt appeared to consist of at least six components and those of Atlantic herring, of at least two components. The relative molecular masses of these antifreezes were 24 000 and 14 600, respectively. Amino acid analysis showed both proteins to be cystine-rich, type II AFPs like those of the sea raven (Hemitripterus americanus). In addition, smelt AFPs were found to be immunologically similar to those of the sea raven. The smelt AFPs differed from those of Atlantic herring and sea raven in that they contained a small amount of glucosamine (~3%). The activity levels of the smelt and herring AFPs were reduced in the presence of dithiothreitol, indicating the functional importance of intact disulfide bonds.

In one experiment, 24 brook trout (Salvelinus fontinalis) in fresh water at 11 ± 1 °C were each orally infected by intubation with two third-stage larvae of "sealworm" (Pseudoterranova decipiens) harvested from the flesh of sea raven (Hemitripterus americanus) and small Atlantic cod (Gadus morhua). In a second experiment, 27 cod in sea water at 0 °C were each force fed, under anaesthesia, four P. decipiens larvae held in a capelin "purse"; these larvae were harvested from large, commercial size cod. Sequential reinvasion by the same P. decipiens larvae was achieved in both of the serial passage experiments. In brook trout, larvae sequentially reinvaded a maximum of two fish, with larvae of cod origin being the more successful at first passage (62.5%) than those of sea raven origin (31.3 and 37.5%). In cod, larvae also achieved sequential reinvasion of a maximum of two fish; the relatively lower success rates of 22.2% (first passage) and 9.1% (second passage) probably reflect the low temperature (0 °C) at which the experiment was conducted.

This chapter examines the red blood cell metabolism in fishes. The potential for the activity of several pathways in fish blood has been demonstrated in several studies. It presents a study of whole blood and washed erythrocytes of the sea raven, Hernitripterus arnericanus , in which the rates of glucose utilization and O 2 consumption are compared. It was found that in whole blood, the calculated O 2 consumption rates from the measured disappearance of total glucose very closely matched measured O 2 consumption rates. The match of respiration rate and glucose consumption was less precise in washed erythrocytes and O 2 consumption rates of washed, unstimulated erythrocytes were approximately 50% of those for whole blood, but glucose consumption remained the same, even when O 2 consumption was doubled by maximal adrenergic stimulation. It was observed that rainbow trout RBCs oxidized lactate poorly, but exhaustive exercise increased lactate oxidation to exceed that of glucose. The increase in lactate oxidation rate is far above that attributable to the increase in substrate concentration alone. This implies that a catecholamine-induced process may be involved.

The circulating Type II antifreeze protein (AFP) in sea raven is 129 amino acids (aa) long (14 kDa) and is derived from an initial 163 aa translation product that is synthesised in the liver. Signal peptide cleavage algorithms, as well as transgenic expression studies in fall armyworm cells, predict the formation of a 146 aa (16 kDa) proprotein intermediate. A protein of this size that cross-reacted with anti-sea raven AFP antibody was detected in sea raven serum using phosphate/urea SDS-PAGE, and was purified by size-exclusion chromatography and reverse-phase HPLC. N-terminal sequencing and mass spectrometry identified the protein as the predicted proAFP, and immunoblotting suggested that it is the predominant form present in liver. These results are consistent with production and storage of a proAFP intermediate in the liver, and its subsequent processing to mature AFP during or soon after its release into the circulation.

Sea raven (Hemitripterus americanus) given intraperitoneal implants of coconut oil containing cortisol (50 mg kg−1) and sampled 5 days later had plasma cortisol, glucose and urea concentrations higher than in a sham-implanted group. No differences in plasma ammonia, free amino acid or fatty acid concentrations were apparent between the cortisol-and sham-treated groups. There was no change in hepatic glycogen content, whereas glutamine synthetase, allantoicase, arginase, aspartate aminotransferase, tyrosine aminotransferase, alanine aminotransferase, glutamate dehydrogenase, phosphoenolpyruvate carboxykinase and 3-hydroxyacyl-coenzyme A dehydrogenase activities were higher in the cortisol-treated fish liver compared with the sham-implanted fish. On the basis of these general increases in enzyme activities, our results suggest that cortisol stimulates nitrogen metabolism in the sea raven. Amino acid catabolism may be a major source of substrate for gluconeogenesis and/or oxidation, while fatty acid mobilization may provide the fuel for endogenous use by the liver in cortisol-treated sea raven. These results further support the hypothesis that cortisol plays a role in the regulation of glucose production in stressed fish.

Among the diverse repertoire of reproductive behaviors shown by sculpins, copulating behavior is known to occur in some species (Breder and Rosen, 1966). Most of these copulating sculpins transfer sperm by using a huge flexible penis (Morris, 1952; Ragland and Fischer, 1987; Munehara, 1988). However, the little dragon sculpin Blepsias cirrhosus, whose penis is too diminutive to be noticed, and the Japanese sea raven Hemitripterus villosus, which does not possess such a functional genital organ, also have been inferred to copulate on the basis of histological observations of eggs collected from, their ovarian cavities (Munehara et al., 1991). It is not clear, however, by what means the sperm of these fishes are actually transferred from the male into the female's ovarian tract. The present study, therefore, was undertaken to clarify this issue by observing copulating and spawning behavior of H. villosus in an aquarium.

Sea raven (Hemitriperus americanus) and ocean pout (Macrozoarces americanus) hearts were excised and perfused in an isolated system. The contractile response of hearts perfused with buffer equilibrated with 100% O2, 100% N2, or 99% O2: 1% CO2 was monitored and work was calculated from mean pressure development times cardiac output. Hearts subjected to either anoxia or hypercapnic acidosis could not sustain mechanical performance as well as hearts perfused with buffer equilibrated with 100% O2. The decrease in mechanical function was not due to an unavailability of ATP. Alternatively it is suggested that contractile failure is related to a decrease in intracellular pH.

1. The ability of fish gills to transfer heat was measured by applying a heat pulse to blood in the ventral aorta and measuring it before and after passing through the gills of a teleost, Hemitripterus americanus. 2. 80–90% of heat contained in the blood is lost during passage through the gills. 3. The fraction of heat not lost during passage through the gills is due to direct transfer of heat between the afferent and efferent artery within the gill bar. 4. The major fraction of metabolic heat (70 - 90%) is lost through the body wall and fins of the sea raven in sea water at 5 degrees C; the remainder is lost through the gills.

The preparation of the in situ heart was accomplished without any physical disturbance to the heart. The heart generated an intrinsic rhythm which was steady throughout the experiment and apparently was derived from the sinoatrial pacemaker. The power output developed by the in situ heart at physiological preloads and after loads was comparable to in vivo values. The effect of increasing preload (0 to 3 cmH2O) was a fourfold increase in stroke volume with little or no change in heart rate. When after load was changed (25 to 45 cmH2O) heart rate was unchanged and stroke volume was usually maintained. As a consequence, cardiac output was maintained by intrinsic factors alone at a higher work load. Epinephrine (10−9 to 10−5 M) in the perfusate produced relatively weak positive chronotropic and inotropic effects. The increase in cardiac output produced by epinephrine was small compared with the intrinsic changes evoked when preload was raised.

A histological survey of the retinas of some fishes has revealed an unusual cone formation. We repeatedly find these unusual triple cones in 10% of the retinas reviewed. To obtain further information about these photoreceptors, the sea raven, whose retina is known to contain them, was chosen for further study. Microspectrophotometric measurements were made to determine the peak absorbance of the visual pigment contained in the three individual outer segments. We report here the results of measurements made on triple cones found in the retina of the sea raven, Hemitripterus americanus.

An in situ heart preparation was used to evaluate cardiac performance in the sea raven, Hemitripterus americanus, under physiological inflow and outflow pressure conditions. Winter and summer fish were subjected to an acute 10 °C temperature change from the seasonal ambient value. The maximum cardiac output under each temperature condition was determined by altering inflow pressure to the heart. Acute temperature increase produced positive chronotropic and inotropic effects in winter fish. Acute temperature decrease produced a negative chronotropic and inotropic effect in summer fish. The inotropic and chronotropic states of the heart were different in winter and summer fish. Intrinsic heart rate was higher in summer fish at all experimental temperatures. The sensitivity of the summer fish hearts to input pressure was also greater, especially during the warm experimen-tal temperatures. It was evident from heartbeat rate measurements and power output calculations that the advent of summer and winter seasons did not promote any compensatory ability in intrinsic heart function.

The antifreeze proteins of the sea raven, Hemitripterus americanus, were isolated and compared with other fish antifreeze proteins. The sea raven contains one major protein of molecular weight 14,000-16,000 with little or no carbohydrate. Except for its similar seasonal appearance, the sea raven antifreeze protein differs from other polypeptide antifreeze in its amino acid composition, secondary structure, and immunological specificity. Amino acid analysis of sea raven antifreeze showed that it contains a high amount of half-cystine, hydrophilic amino acids, and only an average amount of alanine. In contrast, all other fish antifreeze proteins contain approximately 60% alanine and no half-cystine residues. Furthermore, the sea raven antifreeze protein is sensitive to sulfhydryl reagents. The antifreeze activity was decreased by 67% in the presence of 0.01 M dithiothreitol. Circular dichroism studies indicated the absence of significant amounts of alpha-helix and the possible presence of beta-structure. Antibodies raised against the antifreeze protein did not cross-react with the known polypeptide antifreeze from the winter flounder and shorthorn sculpin (Hew, C. L., Fletcher, G. L., and Ananthanarayanan, V. S. (1980) Can. J. Biochem. 58, 377-383). A specific radioimmunoassay was developed for the sea raven antifreeze protein and was used to quantitate the protein concentration in the fish. The seasonal profile obtained by radioimmunoassay was compatible with the antifreeze activity determined with a freezing point osmometer.

Sea raven (Hemitripterus americanus) liver metabolism is similar to liver metabolism in other teleost fishes, with the following two notable exceptions: (1) lactate dehydrogenase levels and lactate utilization rates are extremely low, and (2) fatty-acid oxidation rates are much lower than those in other fish. The interaction of variations in temperature and extracellular pH on sea raven hepatocyte metabolism and intracellular pH were examined by measuring their effects on (1) both the rates of release of $^{14}CO_{2}$ and production of $^{14}C-glucose$ from labeled precursors (glucose, alanine, lactate, and oleate) and (2) the distribution ratios of $^{14}C-5,5$ dimethyloxazolidine-2,4dione (DMO). Temperature increases (from 10 to 18.5 C) resulted in increased metabolic rates ($Q_{10} \cong from$ 2 to 4). However, temperature decreases (from 10 to 2 C) led to marked deactivation of most pathways examined ($Q_{10} \cong from$ 5 to 20). Hexose monophosphate shunt activity was less temperature sensitive than...

The length at which 50% of the individuals were mature was calculated for some Northwest Atlantic groundfish species. Median length at maturity for halibut (Hippoglossus hippoglossus) on the Scotian Shelf declined from 84 cm for males during 1959–1964 to 66 cm during 1970–1979. Median lengths at maturity for females declined from 98 to 70 cm. Ranges of median lengths (centimetres) at maturity for other species were as follows: cusk (Brosme brosme), male 48–56, female 47–56; longhorn sculpin (Myoxocephalus octodecemspinosus), male 24–29, female 23–25; ocean pout (Macrozoarces americanus), male 45, female 28; and sea raven (Hemitripterus americanus), male 36, female 28.

Twelve sea ravens, Hemitripterus americanus, were tested individually for three day periods in electronic shuttleboxes to measure their preferred and avoided temperatures, diel activity pattern and relationship of activity to temperature. The fish avoided temperatures below 9°C or above 25°C, preferring temperatures with a central tendency of 15–17°C. The fish were primarily nocturnal, being more active at night than by day. Locomotor activity increased eightfold between 10 and 20°C, but exhibited an anomalous decrease between 14 and 18°C, corresponding to the preferred-temperature zone, characteristic of maximal summer temperatures in the natural habitat.

Isolated hearts of ocean pout (Macrozoarces americanus) and sea raven (Hemitripterus americanus) were perfused with media containing [14C]lactate or pyruvate and the rate of 14CO2 production was monitored. Increases in exogenous lactate concentration resulted in increases in the rate of lactate metabolism. Under comparable perfusion conditions the rate of decarboxylation of pyruvate was three- to four-fold higher than that of lactate. This finding suggests that lactate oxidation was being limited by lactate oxidase. LDH was purified and the Km values for lactate and pyruvate assessed under conditions of saturating cofactor concentration. Both hearts had a muscle type LDH on the basis of Km (pyruvate). Lactate oxidase from ocean pout and sea raven heart displayed Km values of 25 and 20 mM for lactate, respectively. The Km values were well above the presumptive intracellular level of lactate in the perfused hearts. Considered together, the perfusion and isolated enzyme studies show that the catabolism of exogenous lactate is limited by the reaction catalyzed by lactate oxidase.

Performance by perfused isolated hearts of sea raven (Hemitripterus americanus) and skate (Raja erinecea), representatives of teleost and elasmobranch fishes, respectively, was monitored over a 30 min period under conditions of variable metabolic fuel availability. In both preparations initial cardiac output and hence fuel delivery to the myocardia were comparable to in vivo levels. Pressure development and hence overall work rate of the sea raven heart was also similar to in vivo levels.

The annual cycle of plasma antifreeze polypeptide levels and Na+and Cl−concentrations were measured in sea raven (Hemitripterus americanus) from a New Brunswick population. Both Na+and Cl−concentrations showed a distinct seasonal cycle, with the highest concentration of both ions occurring during the winter months. Mean plasma antifreeze levels also showed a significant seasonal cycle, with the highest values occurring during winter. Two features of the annual plasma antifreeze cycle differed considerably from the annual cycles observed in other temperate water fish: antifreeze polypeptides were present throughout the year and, during the winter, 40–50% of the fish had antifreeze levels that were the same as those observed during the summer. Thus, our results modify the generally accepted view that the presence of plasma antifreeze proteins correlates with the seasonal period of low water temperatures and that only fish inhabiting polar oceans maintain high levels of antifreeze peptides in their blood all year round.

Oxygen consumption rate, myoglobin content, and in vitro activities of key enzymes belonging to the major energy-producing pathways have been determined in the myocardia of sea raven (Hemitripterus americanus) spanning a 20-fold size range. Maximal oxygen consumption rate by the isolated, perfused sea raven heart scaled with body size in a direction similar to whole-animal oxygen consumption. The aerobic indicator, cytochrome oxidase, also showed a distribution that was consistent with the accepted metabolism-size scaling paradigm. The activity of lactate dehydrogenase, on the other hand, increased with increasing body size. This finding does not appear to be indicative of an expanded anaerobic potential in the larger hearts, since pyruvate kinase activity scaled in a negative fashion. This was in contrast to data obtained for sea raven white skeletal muscle, where both pyruvate kinase and lactate dehydrogenase activities increased as body size increased.

The myoglobin content of representative red and white coloured fish hearts was quantitated. It was confirmed that the macroscopic difference in appcarance is due to the presence or absence of myoglobin. Thereafter, the cytochrome c content as well as the maximal activities of key enzymes of energy metabolism were assessed in myoglobin-rich sea raven (Hemitripterus americanus) and myoglobin-poor ocean pout (Macrozoarces americanus) hearts. Both species are sluggish benthic dwellers that occur in similar habitats in the North Atlantic Ocean. The activities of enzymes associated with aerobic metabolism were similar in sea raven and ocean pout hearts, but far in excess of activities observed from white skeletal muscle. The two hearts also displayed comparable activities of enzymes associated with anaerobic energy metabolism. It therefore appears that the capacity to produce reducing equivalents for the electron transport system is similar in two selected fish hearts despite great differences in myoglobin content.