Kamchatka Flounder Research Articles

Community structure of demersal fish over the continental shelf off the southeastern coast of Hokkaido Island: The effect of eurythermy in dominant species

The seasonal dynamics of a boreal demersal fish community and the factor governing its structure have been analyzed, using a total of 169 Danish seine samples collected off the southeastern coast of Hokkaido Island where is an important nursery for Japan Pacific population of walleye pollock Gadus chalcogrammus. The sea floor of the area was covered by cold (<2 °C) Coastal Oyashio Water during spring which was replaced by Oyashio Water and Modified Soya Current Water by autumn. Antlered sculpin Enophrys dicerus was the dominant species accounting for 23.2% of total biomass followed by plain sculpin Myoxocephalus jaok (19.8%), Kamchatka flounder Atheresthes evermanni (8.2%) and walleye pollock (7.4%). Based on species composition and biomass, the samples were classified into the four faunal groups: i) upper-shelf assemblage in which antlered and plain sculpins in combined accounted for 61.4%, ii) mid-shelf assemblage dominated by antlered sculpin (27.0%) and various fish taxa iii) lower shelf assemblage dominated by gadids (32.8%) and iv) less abundant lower-shelf assemblage dominated by antlered sculpin (33.3%) and other cottoid species (30.4%). Depth was the most important factor determining the structure of assemblages accounting for 66.2% of the variance explained by environmental variables, outweighing the effects of season (19.4%) and temperature (14.4%). This result was ascribed to the eurythermy of the dominant species which persisted at relatively narrow depth ranges under the seasonally fluctuating thermal environments.

Modern state of stocks for demersal and pelagic fishes on the shelf of Olyutorsky-Navarin area

Stocks of demersal and pelagic fish species are assessed for the bottom layer over the outer shelf and upper continental slope between Cape Olyutorsky and Cape Navarin (northwestern Bering Sea) on the data of bottom trawl survey conducted aboard RV Professor Levanidov over the isobaths 20-400 m in the summer of 2019. The total biomass of demersal fish in the surveyed polygon was estimated as 682,262 t; the portion of pacific cod was 51.50 %, arrowtooth flounder — 9.80 %, great sculpin — 9.64 %, rock sole — 4.60 %, alaska skate — 4.57 %, flathead flounders — 2.56 %, yellow irish lord — 2.30 %, and &lt; 2 % for other species. The total biomass of pelagic fish species in the bottom layer was estimated as 759,639 t (species-specific coefficients of catchability were used); the portion of adult walleye pollock was 85.12 %, its juveniles — 9.94 %, pacific herring — 4.67 %, and other pelagic species — 0.27 % in sum. Mean ratios of the species stock between the surveyed polygon and other areas of the northwestern Bering Sea, as the Gulf of Anadyr and the deeper continental slope (below 400 m), were evaluated using the data of bottom trawl surveys conducted in 2005-2017. Some species as yellow irish lord, saffron cod, pacific halibut, arrowtooth flounder, great sculpin, kamchatka flounder, rock sole, and aleutian skate distributed mostly within the polygon and their mean biomass in the outside areas varied from 0.5 % to 69.2 % relative to the biomass in the polygon surveyed in 2019. On the contrary, the portions of pacific cod, greenland halibut, alaska skate, and walleye pollock were larger outside the polygon — from 102.9 to 190.4 %, and almost entire stocks were in the outside areas for alaska plaice, flathead flounders, and pacific herring — from 533.4 % to 1380.5 % relative to the biomass accounted within the polygon. The stocks assessed in 2019 reflected both the state of populations and their spatial and bathymetric redistribution, mostly because of the St. Lawrence Cold Water Pool shrinkage at the bottom of the Gulf of Anadyr. The stocks fluctuations are reasoned mainly by natural factors, rather than fishery impact.

Quantitative Estimation and Comparison of the Trophic Niches of the Kamchatka Flounder Atheresthes evermanni, the Pacific Halibut Hippoglossus stenolepis, and the Greenland Halibut Reinhardtius matsuurae, by the Isotope Composition of Carbon and Nitrogen of the Food Components

The width of trophic niches of the Kamchatka flounder Atheresthes evermanni, the Pacific halibut Hippoglossus stenolepis, and the Greenland halibut Reinhardtius matsuurae have been assessed quantitatively on the Western Kamchatka shelf of the Sea of ​​Okhotsk using the data of isotopic signatures of carbon (δ13C) and nitrogen (δ15N) of their prey. According to the corrected standard ellipse area, the trophic niche widths of the Kamchatka flounder, Pacific halibut, and Greenland halibut are 11.35, 9.41, and 12.36, respectively. The range of δ15N isotopic signatures (8.80–17.61) corresponds to the trophic level 2.63–5.22. According to the limits of variation of δ13C (–14.99… –22.9), the basic carbon sources for halibuts are the prey groups belonging to plankton, nekton, and nectobenthos. The maximum value of the niche overlap belongs to the Kamchatka flounder (93.25%) in the niche of the Greenland halibut; the minimum, on the contrary, belongs to the Greenland halibut (73.19%) in the niche of the Kamchatka flounder. The high degree in similarity of system-wide niche indicators calculated from the isotopic signatures of halibut/flounder prey is balanced by the differences of other parameters in specific habitats: depth, temperature, and food spectra variability in ontogenesis.

Using species distribution models to describe essential fish habitat in Alaska

Describing essential habitat is an important step toward understanding and conserving harvested species in ecosystem-based fishery management. Using data from fishery-independent ichthyoplankton, groundfish surveys, and commercial fisheries observer data, we utilized species distribution modeling techniques to predict habitat-based spatial distributions of federally managed species in Alaska. The distribution and abundance maps were used to refine existing essential fish habitat descriptions for the region. In particular, we used maximum entropy and generalized additive modeling to delineate distribution and abundance of early (egg, larval, and pelagic juvenile) and later (settled juvenile and adult) life history stages of groundfishes and crabs across multiple seasons in three large marine ecosystems (Gulf of Alaska, eastern Bering Sea, and Aleutian Islands) and the northern Bering Sea. We present a case study, featuring Kamchatka flounder (Atheresthes evermanni), from the eastern and northern Bering Sea to represent the &gt;400 habitat-based distribution maps generated for more than 80 unique species–region–season–life-stage combinations. The results of these studies will be used to redescribe essential habitat of federally managed fishes and crabs in Alaska.

Temporal records of diet diversity dynamics in individual adult female Steller sea lion (Eumetopias jubatus) vibrissae

Detailed information on the nutrition of free-ranging mammals contributes to the understanding of life history requirements, yet is often quite limited temporally for most species. Reliable dietary inferences can be made by analyzing the stable carbon (C) and nitrogen (N) isotopic values (δ13C and δ15N) of some consumer tissues; exactly which tissue is utilized dictates the inferential scope. Steller sea lion (SSL) vibrissae are grown continuously without shedding and thus provide a continuous multi-year record of dietary consumption. We applied a novel kernel density approach to compare the δ13C and δ15N values along the length of SSL vibrissae with δ13C and δ15N distributions of potential prey species. This resulted in time-series of proportion estimates of dietary consumption for individual SSL. Substantial overlap in δ13C and δ15N distributions for prey species prevented a discrete species-scale assessment of SSL diets; however, a post hoc correlational analysis of dietproportion estimates revealed grouping by trophic level. Our findings suggest that adult female SSL diets in the western and central Aleutian Islands shift significantly according to season: diets contain a higher proportion of lower trophic level species (Pacific Ocean perch, northern rockfish, Atka mackerel and walleye pollock) in the summer, whereas in the winter SSL consume a much more diverse diet which includes a greater proportion of higher trophic level species (arrowtooth flounder, Kamchatka flounder, darkfin sculpin, Pacific cod, Pacific octopus, rock sole, snailfish, and yellow Irish lord).

Trophic Niche Separation between Sympatric Sibling Flatfishes in Relation to Gill Raker Morphology

AbstractArrowtooth Flounder Atheresthes stomias and Kamchatka Flounder A. evermanni are upper‐trophic‐level predators that have been considered trophically equivalent in their sympatric range. Here, we present evidence against trophic equivalence of these sibling species based on flounder size and space‐stratified analyses of stomach content data from 5,724 flounder sampled from the eastern Bering Sea (EBS) during summer 2007–2016. We found that interspecific trophic niche separation occurred at sizes up to 39 cm FL before convergence at larger size‐classes. Our findings are consistent with the hypothesis that foraging efficiency differences arise due to divergence in gill raker counts. Arrowtooth Flounder, which have more gill rakers than Kamchatka Flounder, consistently consumed more zooplankton than Kamchatka Flounder, while Kamchatka Flounder typically consumed more benthic fishes. Although a benthivory–zooplanktivory axis of resource partitioning is common among sympatric trophic polymorphs in freshwater ecosystems, our findings are novel for marine sibling species and flatfishes (Pleuronectiformes). Abundance estimates for both Arrowtooth Flounder and Kamchatka Flounder have substantially increased in Alaska during recent years, and we suggest that trophic niche separation alleviates interspecific competition, which may buffer sympatric carrying capacities for these two flatfishes.

Fecundity of the Far-Eastern flatfishes Pleuronectiformes. 1. General characterization of fecundity of Pleuronectiformes in the northern part of the Pacific Ocean

Cited and archive data on fecundity of 31 flatfish species are generalized for the North Pacific. General characterization of the fecundity is presented and correlation between absolute individual fecundity of the females and their body length or age is analyzed and formalized in equation form. Spatial variability of fecundity is described for different species: pacific halibut and starry flounder have the highest absolute fecundity in the eastern Bering Sea and Okhotsk Sea, greenland halibut, yellowfin sole, alaska plaice, sakhalin flounder, longhead dab, and flathead sole - in the Okhotsk Sea, northern rock sole - in the waters at East and West Kamchatka. kamchatka flounder - in the Bering Sea, arrowtooth flounder - in the Pacific waters at North America. So, the Okhotsk Sea is the area where the absolute fecundity of majority wide-spread flatfish species can reach the maximal level. However, the maximal fecundity of longsnouted flounder is higher in the Japan Sea than in the Okhotsk Sea.

Taxonomy of the early life stages of arrowtooth flounder (Atheresthes stomias) and Kamchatka flounder (A. evermanni) in the eastern Bering Sea, with notes on distribution and condition

Arrowtooth flounder (Atheresthes stomias) and Kamchatka flounder (A. evermanni) are closely related flatfish species that co-occur in the eastern Bering Sea. As adults, arrowtooth flounder can be distinguished from Kamchatka flounder; however, larvae and early juveniles can only be indentified to the genus level due to morphological similarities. This has precluded studies of ecology for the early life stages of both species in the eastern Bering Sea. In this study, we developed a genetic technique to identify the larvae and early juveniles of the two species using mtDNA cytochrome oxidase subunit I (COI). Genetically identified specimens were then examined to determine a visual identification method based on pigment patterns and morphology. Specimens 6.0–12.0mm SL and≥18.0mm SL can be identified to the species level, but species identification of individuals 12.1–17.9mm SL by visual means alone remains elusive. The distribution of larvae (<25.0mm SL) of both arrowtooth flounder and Kamchatka flounder is similar in the eastern Bering Sea; however, juvenile (≥25.0mm SL) Kamchatka flounder occur closer to the shelf break and in deeper water than juvenile arrowtooth flounder. Condition was determined for larvae and juveniles of each species by analyzing lipid content (%) and energy density (kJ/g dry mass). Kamchatka flounder larvae on average had higher lipid content than arrowtooth flounder larvae, but were also larger on average than arrowtooth flounder larvae in the summer. When corrected for length, both species had similar lipid content in the larval and juvenile stages.

Arrow-toothed halibuts Atheresthes spp. (Pleuronectiformes, Pleuronectidae) and their role in the fish community of Olyutorsky-Navarin region and adjacent areas of the Bering Sea

Based on the trawl surveys of 1996–2012, regularities and biological features have been studied in the arrow-toothed halibuts (Atheresthes evermanni and A. stomias) from Olyutorsky-Navarin region and adjacent waters of the Bering Sea. The abundance of the species has increased since 2004. Their remunerative concentrations have been found on the continental slope and shelf. The majority of fish captured during our survey were mature specimens with a length of 37–54 cm and a weight of 0.8–1.4 kg; in the course of our investigation, there was a trend towards a decrease in the average sizes. According to the data obtained in the recent years, if one considers the biomass parameters, arrow-toothed halibuts are among ten dominant species (0.1–0.5% of the total biomass of fish registered in Olyutorsky-Navarin region) and prevail among flatfish (Pleuronectidae). Currently, arrow-toothed flounders are undesirable bycatch in the fishery of Reinhardtius hippoglossoides and Hippoglossus stenolepis.

Abiotic and biotic factors affecting recruitment variability of walleye pollock (Theragra chalcogramma) off thePacific coast ofHokkaido,Japan

AbstractAbiotic and biotic factors affecting the recruitment variability of the Japanese Pacific stock (JPS) of walleye pollock (Theragra chalcogramma) were examined using a bivariate regression and multivariate combined model. Of the abiotic variables aroundFunkaBay (spawning ground), February sea surface temperature (SST) and wind direction index showed significant bivariate relationships with recruitment. FebruarySSTwas positively related to recruitment, suggesting that warmer water temperature inFebruary favorsJPSrecruitment. On the other hand, the relationship betweenFebruary wind direction index and recruitment predicts highJPSrecruitment under predominant northwest winds in February. For the biotic variables in theDoto area (nursery ground), significant and negative bivariate relationships with recruitment were observed for catch per unit effort ofKamchatka flounder (Atheresthes evermanni),Pacific cod (Gadus macrocephalus), and walleye pollock, implying an important impact of predation by these groundfishes onJPSrecruitment. The overall model incorporating these abiotic and biotic factors successfully reproduced the variability inJPSrecruitment. Temperature and wind conditions around the spawning ground along with predator condition in the nursery ground appear to play a dominant role in the recruitment dynamics ofJPS. Based on these results and prior knowledge, we propose a new hypothesis to explain the processes controllingJPSrecruitment.

Record of the Kamchatka Flounder, Atheresthes evermanni, in California Waters

Record of the Kamchatka Flounder, Atheresthes evermanni, in California Waters

Female maturity, reproductive potential, relative distribution, and growth compared between arrowtooth flounder (Atheresthes stomias) and Kamchatka flounder (A. evermanni) indicating concerns for management

Summary Arrowtooth flounder (Atheresthes stomias) and Kamchatka flounder (A. evermanni), major piscivorous predators in the eastern Bering Sea and Aleutian Islands, are morphologically similar. Consequently the two species have been managed together as a species complex using the length- and age-at-maturity derived from Gulf of Alaska arrowtooth flounder, which had been the only available maturity estimates. However, there could be serious management consequences if the two species matured at significantly different ages and fork lengths. Therefore, this study was conducted during 2007 and 2008 to determine if there were significant differences in maturation between the two species. Significant differences in size and age of female maturation and growth were found. The age and length of 50% maturity (A50,L50, respectively) for arrowtooth flounder females is 7.6 years of age and 480 mm in body length. In comparison, A50,L50 of Kamchatka flounder females is 10.1 years of age and 550 mm, meaning that Kamchatka flounder has a significantly lower reproductive potential than arrowtooth flounder. The large difference in reproductive potential indicates that managing the two species together as a species complex using the reproductive characteristics of arrowtooth flounder, was not conservative for Kamchatka flounder. This study also determined that arrowtooth flounder maturation was consistent between the Gulf of Alaska and eastern Bering Sea populations.

Distribution patterns of five pleuronectid species on the continental slope off the Pacific coast of northern Honshu, Japan

Information on the distributions of demersal and benthic fishes is fundamental for stock assessment and management. Spatiotemporal changes in the distribution patterns of five pleuronectid species (flathead flounder Hippoglossoides dubius, Kamchatka flounder Atheresthes evermanni, roughscale sole Clidoderma asperrimum, slime flounder Microstomus achne, and Korean flounder Glyptocephalus stelleri) off the Pacific coast of northern Honshu, Japan, at depths of 150–900 m, were examined using a generalized linear mixed model (GLMM). Densities of flathead and Korean flounder were highest in the southernmost area, where the fish were small. The body lengths of both of these species increased from 2003 to 2008, suggesting that an abundant year class was recruited in 2003. The density of Kamchatka flounder was highest in the northern area. In roughscale sole and slime flounder, there were no distinctive annual and latitudinal trends in the density distributions. The density distribution of Korean flounder was bimodal; the peaks were at depths of 210 and 410 m. The body length increased as the depth increased from 150 to 410 m, and then decreased from 410 to 550 m. Moreover, “bigger–deeper” trends were observed in flathead, Kamchatka and slime flounder.

Distribution of retinylester-storing stellate cells in the arrowtooth halibut, Atheresthes evermanni

Hepatic stellate cells play a major role in retinylester storage in mammals, but the retinoid-storing state in nonmammalian vertebrates remains to be elucidated. In this study, we examined retinoids and retinoid-storing cells in the arrowtooth halibut, Atheresthes evermanni. High-performance liquid chromatography analyses revealed the highest concentrations of stored retinoids (retinol and retinylester, 6199 nmol/g) in the pyloric cecum, a teleost-specific organ protruding from the intestine adjacent to the pylorus. Considerable amounts of retinoids were also stored in the intestine (3355 nmol/g) and liver (1891 nmol/g), and small amounts in the kidney (102 nmol/g). Very small amounts or no retinoids were detected in the heart, gill, skeletal muscle, and gonads (less than 2 nmol/g). Use of gold chloride staining and fluorescence microscopy to detect retinoid autofluorescence showed that, in the pyloric cecum and intestine, retinoid-storing cells were localized in the lamina propria mucosae. Under electron microscopy, cells containing well-developed lipid droplets, which are common morphological characteristics of the hepatic stellate cells of mammals, were observed in the lamina propria mucosae of the pyloric cecum. Thus, the distribution of stellate cells with retinoid-storing capacity differs between this halibut and mammals, suggesting that the retinoid-storing site has shifted during vertebrate evolution.

Demersal fish fauna in the Doto nearshore waters, northern Japan: Species composition and seasonal variation

The species composition of demersal fish was studied in nearshore waters (33-116 m depth) of south-eastern Hokkaido, the coldest area around the Japan Archipelago due to the influence of the cold Oyashio Current, using bottom gillnet samples collected during October 1996, August 1997, May 1998 and September 1999. The water temperature just above the sea bottom in the study area was lowest (<2°C) during May and then rose through autumn (>14°C). Cottids were the most abundant family in terms of both overall biomass and number, but their gravimetric dominance decreased from May (84%) through October (14%), whereas pleuronectids and stichaeids increased. Of the 57 fish species sampled, plain sculpin Myoxocephalus jaok was the dominant species in terms of overall biomass, accounting for 29.0% of the total biomass, followed by horned sculpin Enophrys diceraus (19.5%), Kamchatka flounder Atheresthes evermanni (6.5%) and blackline prickleback Acantholumpenus mackayi (4.9%). Plain sculpin dominated during May and September, but its predominance was low during October (9.6%), when witch flounder Glyptocephalus stelleri (22.7%) and blackline prickleback (10.8%) became important. This seasonal change appears to reflect the annual life cycle events of the fish, such as spawning.

On the Morphology of Arrowhead Flounders of the Genus Atheresthes in the Pacific Waters of the Northern Kuril Islands and Southeastern Kamchatka

This paper presents the results of studies on the morphology of arrowhead flounders, the Kamchatka flounder Atheresthes evermanni (35 specimens), and the American arrowtooth flounder A. stomias (37 specimens) collected in Pacific waters of the northern Kuril Islands and southeastern Kamchatka in 1998–1999. The morphology of the discussed species is compared with that of arrowtooth flounders from other areas. From this comparison, available information on the sharp increase in the density of the American arrowtooth flounder in the surveyed area (since 1997), and similarities in size compositions of the fish in Kuril and Aleutian waters, a conclusion has been made about the penetration of this species from Aleutian Pacific waters into the area of the northern Kuril Islands and southeastern Kamchatka. This is a result of expansion of the geographical range of this species due to general water warming in the northwestern Pacific during the second half of the 1990s.