Distribution and some features of biology of representatives of the genus Lycodes in the western part of the Bering Sea in the summer period

Based on materials of bottom inventory trawl survey performed in summer 2008 in the western part of the Bering Sea, we show that representatives of the genus Lycodes in the summer period occur almost throughout the study water area of the sea from the sublittoral to the drop-off. The pattern of distribution and abundance of particular species depend on the depth and specific features of the hydrological regime of the given area. The most numerous species??Lycodes brevipes and L. palearis??are found in warm intermediate and in cold demersal water masses, are distributed over a vast stretch, and there form considerable concentrations. Deep-water species??L. beringi and L. concolor??are more stenothermal, occur along the narrow band of the continental slope, and are considerably inferior to stretch species in numbers. Of shallow species dwelling at depths smaller than 100 m, only L. raridens has high numbers and occurs over a considerable area in the northern part of the study area, the remaining species (L. mucosus, L. polaris, and L. turneri) are caught in small amounts at local sites. The largest sizes are in L. raridens and L. concolor, their maximum length in catches is more than 70 cm, the former species reaches maximum length in the seventh year of life, and the latter reaches maximum length in the ninth year. The smallest and slowest-growing among the studied fish is L. brevipes: its maximum length in catches does not exceed 39 cm and maximum age is 7 years.     

Distribution and some features of the biology of the eelpout Lycodes tanakae Jordan et Thompson, 1914 (Perciformes: Zoarcidae) in the Tatar Strait, Sea of Japan

Based on data from studies that were performed in 2006, 2007, and 2009, we analyzed the distribution and some features of the biology of the eelpout Lycodes tanakae, which inhabits the Tatar Strait. The young of this species (<30 cm in TL) predominantly occur to the north of 50° N. The largest individuals (>71 cm in TL) are found to the south of 49° N and medium-sized fish occur throughout the studied area. In the Tatar Strait, L. tanakae inhabits the 50?C615 m depth range, but the majority of the eelpouts (67.9%) were caught from depths of 200?C600 m. Small individuals of this species (<30 cm in TL) occur at depths of 50?C200 m, while medium-sized and large fish (>30 cm in TL) can be found at all depth horizons that were surveyed. The mean linear size of L. tanakae increases with an increase in the depth of their habitat. The relationship between the spatial distribution of L. tanakae and water temperature regime is discussed. The nutritional spectrum of L. tanakae includes 18 food items, with fish and shrimp predominating. Young L. tanakae (<30 cm in TL) are benthophages, 41?C50-cm individuals feed mainly on cephalopods and fish.     

Distribution of the Eelpout Lycodes soldatovi(Pisces: Zoarcidae) over the Continental Slope of the Sea of Okhotsk

The eelpout Lycodes soldatovi was found at depths of 153 to 1005 m in the Sea of Okhotsk; however, it usually inhabits the depth range of 400 to 800. The mean and maximum abundance and the biomass of this species were 198.5 and 1037 individuals per km² and 173.7 and 1275 kg/km², respectively. In view of the data on the distribution of young fish (up to 30 cm in total body length) and the reports on the absence of Lycodes larvae, a hypothesis was developed that this species spawns predominantly in the waters off western Kamchatka and eastern Sakhalin at the depth range of 700 to 900 m. Large individuals (>50 cm) exhibit higher migratory activity and are more tolerant of environmental conditions. That is why they are encountered throughout the distribution area of this species, even in subzero temperature areas. Lycodes soldatovi seems to be a typical inhabitant of the Sea of Okhotsk, except for the waters off the South and Central Kuril Islands and the Pacific waters off the North Kuril Islands.     

Species Composition,Distribution, and Some Biological Aspects for Fishes of the Genus Lycodes (Zoarcidae) in the Laptev Sea in 2014

Journal of Ichthyology - On the basis of material from expeditions to the Laptev Sea in 2014, information is presented on occurrence, spatial-bathymetric distribution, water temperature and...     

Lycodes nishimurai, a new deep-sea eelpout (Teleostei: Zoarcidae) from the Sea of Japan

A new zoarcid fish, Lycodes nishimuari, is described on the basis of four specimens from the Yamato Bank, the Sea of Japan, at depths of 642–669 m. Although this species resembles Lycodes diapterus, L. hubbsi, L. pectoralis, L. macrochir, and L. nakamurae in having a deep notch in the pectoral fin and a single lateral line on the body, it is distinguished from them by the following combination of characters: no scales on pectoral fin base; scales on dorsum before dorsal fin origin; suborbital, preopercular, and last postorbital pores with risen rim; whitish lips; no whitish transverse bars on body; pectoral fin membrane and anterior part of dorsal fin membrane without black spots; basal color of vertical fins black. Supplementary material to this paper is available in electronic format at .     

Spatial distribution and some features of biology of the two-line eelpout Bothrocara brunneum (Zoarcidae) in the Sea of Okhotsk

According to data of integrated trawl surveys, specific features of distribution and some traits of biology of the two-line eelpout Bothrocara brunneum in the Sea of Okhotsk are shown. The species under investigation is spread over the entire sea, and the average density of its distribution averages 0.29 ind./km² or 0.11 kg/km². It is found at depths of 200–1995 m, mainly in the range of 300–900 m. Juveniles inhabit large depths, while large individuals are distributed over the entire slope. Optimal temperature of habitation is 1.5–2.3°C. The main center of reproduction is the slope of the northern part of the sea. In catches, individuals with a length of 6–71 (on average, 41) cm and a weight of 20–2600 (757) g occur. Sexual maturation takes place on reaching a length of 45–50 cm; at the same time, gravimetric increments begin to be ahead of linear ones. Sex ratio is 1 : 1. Sexual dimorphism with respect to sizes was not revealed. Spawning is extended: individuals with mature gonads are found in the summer-autumn period. In net catches, fish aged 4–8 years dominate, while fish aged 2–7 years dominate in trawl catches.     

Some biological features and productive characteristics of <Emphasis Type="Italic">Oithona similis</Emphasis> (Copepoda) in the Sea of Okhotsk and western Bering Sea

The biological peculiarities of Oithona similis were described based on the materials from 29 complex surveys that were conducted by the TINRO Center in the Sea of Okhotsk and the western Bering Sea from 1986 to 2005 and the production of the species was estimated. In this area, O. similis produces four generations a year, viz., one in the spring, one in the fall, and two in the summer. The peak of spawning in May and June coincides with the maximum development of phytoplankton. Somatic production of O. similis in both seas becomes higher during the summer season. In this species, the largest increment in body weight begins with the copepodite stage CIV, when basic nutrients are accumulated. The average specific daily production of O. similis in the epipelagic zone of the Sea of Okhotsk and Bering Sea was 0.0092 and 0.01 in the spring, 0.043 and 0.031 in the summer, and 0.023 and 0.014 in the fall, respectively. The total somatic production of this species reached 28.318 million tons in the Sea of Okhotsk and 4.811 million tons in the Bering Sea. The Sea of Okhotsk is more favorable for the development of O. similis.     

Spatial distribution and thermal regime of habitation of two representatives of the genus Lycodes (Perciformes: Zoarcidae) in Russian waters of the Sea of Japan

Main features of spatial distribution and thermal regime of habitation of Lycodes nakamurae and L. yamatoi in Russian waters of the Sea of Japan are discussed. Comparative analysis of specific features of distribution of eelpouts of the mesobenthal group (L. nakamurae, L. yamatoi, L. tanakae) in some areas of the Sea of Japan with different hydrological conditions is provided. No horizontal migrations directed along isobaths were revealed in these species. In Russian waters of the Sea of Japan, L. nakamurae inhabits depths 130–760 m, preferring the range of depths 200–700 m (it was found in catches of 95.7% of trawlings); L. yamatai inhabits depths 140–800 m, but most frequently is found in the range of depths 200–500 m (86.1% of trawlings). L. nakamurae occurs at a temperature of 0.4–1.2°C and L. yamatoi is found at 0.3–1.9°C. Seasonal migrational activity in the former species is more pronounced than in the latter. Spring-summer migration towards the shelf for feeding and reproduction and autumn-winter wintering migration towards the continental slope taking place with the cooling of the shelf are noticeable. Maximum range of vertical migrations is typical of medium-size fish and minimal is typical of juveniles of the studied species that inhabit the upper section of the bathyal (200–400 m). It is suggested that the lower limit of distribution of eelpouts of the mesobenthal group in the southern and northern sectors of the Sea of Japan coincide. The upper boundary of habitation of the species in different seasons of the year is totally determined by the thermal regime of water masses in different areas of the sea.     

Subtropical migrants in the southwestern part of the Bering Sea

From 2003 to 2008, arrivals (including mass) of sea bream Brama japonica, saury Cololabis saira, and spiny dogfish Squalus acanthias, as well as some cases of catches of Japanese anchovy Engraulis japonicus, and Todarodes pacificus, and Onychoteuthis borealijaponica squids were recorded in Pacific waters of Kamchatka in the southwestern sector of the Bering Sea. The penetration of these species far to the north is related to feeding migrations as well as to the passive transfer of water by currents. Migrations of subtropical species to Pacific waters of Kamchatka and the southern part of the Bering Sea depend on thermal conditions and circulation of currents in each particular year and are determined, first of all, by the intensity of the Western Subarctic gyre, although in some years, the migration flow of B. japonica and C. saira from the northeastern part of the Pacific Ocean increases.     

New data on eelpouts (Pisces: Zoarcidae) from the south-western part of the Sea of Japan

On the basis of standard trawl survey made at the shores of the Republic of Korea in the Sea of Japan, species composition, ratio of species in catches, and size composition of eelpouts (fam. Zoarcidae) at depths 123–330 m is analyzed. Five species of eelpouts are found in the investigated region: Bothocara hollandi, Lycodes nakamurae, L. sadoensis, L. tanakae, and Petroschmidtia toyamensis. For the first time for the south-western part of the Sea of Japan, quantitative characteristics of distribution, size composition, and bottom temperature of capture are reported for each eelpout species. L. sadoensis is a common species in this region.     

Distribution and food habits of two similar species of <Emphasis Type=Italic>Bothrocara</Emphasis> (Perciformes: Zoarcidae) in the eastern Bering Sea

Six of the eight currently recognized species of the zoarcid genus Bothrocara are known from the eastern Bering Sea. Two of these species, B. brunneum and B. zestum, are widespread and commonly encountered on the upper continental slope, although B. zestum was not widely recognized as a distinct species in the region until 2004. During the summers of 2004 and 2008, large-scale bottom trawl surveys were conducted along the upper continental slope of the eastern Bering Sea from Bering Canyon to the U.S.-Russian border. Over the course of these surveys, distribution, relative abundance, length frequency, length-weight, and stomach contents information was collected for B. brunneum and B. zestum. Data collected on the surveys indicate that these two species have broadly overlapping geographic and bathymetric distributions in the region, but that their population numbers are substantially different. Length-weight regressions show that although these two species reach approximately the same maximum length, B. brunneum is substantially heavier than B. zestum at all lengths over about 40 cm. Stomach contents analysis indicates that the diet of B. brunneum consists primarily of various species of shrimps and mysids, while B. zestum is primarily piscivorous, consuming primarily bathylagids and other zoarcids. Therefore, despite their general morphological similarity, these two species function very differently in the eastern Bering Sea benthic ecosystem.     

Morphology of two eastern Pacific eelpouts (Pisces,Zoarcidae, Lycodes) in connection with features of distribution of species with a double lateral line

Morphology of two endemic eastern Pacific species of eelpouts—blackbelly Lycodes pacificus Collett, 1879 and bigfin L. cortezianus Gilbert, 1891—were studied. It was shown that these two species are characterized by unreduced seismosensory system of the head and belong to a species group with a double lateral line. It was suggested that the ancestral form of this species group could have possibly dispersed in the Atlantic Ocean through the Panama Canal in the pre-Pleistocene time. It is likely that the antitropical distribution of the Newfoundland eelpout L. terranovae is related this event.     

Distribution and some biological features of skate <Emphasis Type="Italic">Bathyraja parmifera</Emphasis> (Rajidae,Rajiformes) in the northwestern part of the Sea of Japan

In the northwestern part of the Sea of Japan, skate Bathyraja parmifera in catches of the bottom trawl occurs at depths of 40 to 830 m at the near-bottom temperature of 0.4–4.9°C. Throughout the year, the skate performs migrations within the continental slope and, in the feeding period, inhabits mainly the depth range of 300 to 500 m. Maximal average density of aggregations of B. parmifera is observed in waters of northern Primorye; minimal average density is observed in Peter the Great Bay and on the Yamato Bank. In catches, skates with a length of 17–130 cm and a weight of 0.5–18.8 kg are recorded; however, fish with a length of 80–115 cm dominate. Individuals with a length of up to 40 cm feed mainly on amphipods, and larger immature and adult individuals feed on decapods, cephalopods, and fish. The value of the daily ration of B. parmifera with its growth decreases from 2.4 to 0.9% of the body weight. Specific ecological features of B. parmifera are a cause of its considerable underfishing by the bottom trawl; therefore, the total resource of this species in the considered region may be at the level of maximal estimates obtained during surveys and comprise no less than 20000 t.     

Phylogeny of the eelpout genus Lycodes (Pisces,Zoarcidae) as inferred from mitochondrial cytochrome b and 12S rDNA

The bottom-dwelling and species-rich eelpout genus Lycodes Reinhardt has a great potential for the study of Arctic marine speciation. Subdivision of the genus has been based on single or few morphological characters (e.g., lateral line configuration) with contradicting results and phylogenetic approaches have not been attended. Here we present the first phylogenetic analysis of the genus employing DNA sequences of the mitochondrial genes cytochrome b and 12S rDNA (714 bp). The analysis with the two genes combined resulted in two equally parsimonious trees. In both cladograms most of the previously suggested subgroups are para- or polyphyletic, except for the so-called short-tailed Lycodes spp., with a short tail, a single mediolateral lateral line configuration and a shallow or filled otolith sulcus. The group of long-tailed Lycodes spp., with ventral or ventro-medio-lateral types of lateral line configuration and a deep otolith sulcus, appears to be paraphyletic, since Pacific and Atlantic species in this group are not each other's closest relatives. Thus, the short-tailed species are placed in a derived clade, indicating a secondary shortening of the tail, and a "slope to shore" type of evolution. This is not in accordance with earlier assumptions of the more elongate, deeper living species being the more derived. The basal position of long-tailed Pacific species supports earlier theories of Pacific origin of the genus/family. Small genetic differences between Arctic/Atlantic species indicate a rather recent radiation in these areas after the opening of the Bering Strait 3.0-3.5 million years ago.     

The distribution and some biological features of Stichaeus grigorjewi (Stichaeidae) in the waters of northern Primorye (The Sea of Japan)

Stichaeus grigorjewi is a common species, but in the waters of northern Primorye it is comparatively rare. It occurs at depths down to 465 m for the greater part of the year, except for the spawning period, staying in deep-water masses with relatively stable temperature conditions. The widest bathymetric distribution of S. grigorjewi is observed from spring-early summer. After the completition of spawning, it shifts to depths larger than 100 m and winters in the upper section of the continental slope. During each season maximum concentrations of S. grigorjewi along the coasts of Primorye are observed in water from Povorotnyi Cape to the Olga Gulf. Males and females of this species have close rates of growth and reach an age of not less than 12+ years. Most individuals of S. grigorjewi in catches had a length of 37 to 44 cm and fed mainly on fish.     

Variation of coloration in <Emphasis Type=Italic>Lycodes yamatoi</Emphasis> Toyoshima, 1985 (Pisces: Zoarcidae) in the northern Sea of Japan

Specimens of eelpouts were found in the northern Sea of Japan that were externally similar to Lycodes yamatoi Toyoshima, 1985, but their coloration differed from the coloring known for this species. Comparative analysis of meristic characters and sequence comparison of mtDNA COI and cytb gene fragments did not reveal distinctions between specimens with different types of coloration. All studied specimens belong to L. yamatoi. The live color pattern of L. yamatoi is characterized by high variation, with two main types of coloration, “dark” and “bright.”     

Allometric variation and sexual dimorphism in <Emphasis Type=Italic>Lycodes yamatoi</Emphasis> Toyoshima, 1985 (Perciformes: Zoarcidae) from the Sea of Japan

A detailed analysis of allometric variation and sexual dimorphism in Lycodes yamatoi (Perciformes: Zoarcidae) was carried out using an original method developed by the authors. An allometric pattern of growth was revealed not only in plastic but in some meristic characters, such as the number of teeth on the bones of the mouthparts and the number of gill rakers on the first gill arc. It was determined that most of the morphological characters of L. yamatoi were subjected to positive allometric variability (the proportions of the head and the anterior part of the body), while growth of the remaining characters was specified by negative allometry (the length of the rays of pair and caudal fins, interorbital distance, and isthmus width) and isometry (the standard length, ante-anal distance, and head width on the vertical neck). The juveniles of L. yamatoi have no significant sexual distinctions either in plastic or in meristic characters. Adult females and males of L. yamatoi significantly differed by characters composing the head complex, the actual length of the head, and correlatively related with it ante-dorsal and ante-pectoral distances. The dimensional indexes of antedorsal and ante-pectoral distances, and the relative sizes of maxillary bones (lmx/c) are of the greatest diagnostic value for sex differentiation.     

Length–weight relationships of deep-sea fishes from the western Bering Sea

Length–weight relationships are lacking for most deep-sea fishes. This study presents length–weight relationships for 42 species from the western Bering Sea. Results show significantly different relationships between females and males for 11 species and between juveniles and adults of four species. A plot of length–weight estimates, log a over b , showed the deep-sea fishes in this study to be more of the elongated shape compared with other marine fishes.