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Izvestiya TINRO

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Vol 202, No 2 (2022)
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BIOLOGICAL RESOURCES

245-254 336
Abstract

A long discussion about either marine or freshwater genesis of salmonids is still relevant today. So far, no convincing evidence of any point of view has been found. The arguments to freshwater origin of Salmoniformes are analyzed using the «probabilistic» method of phylogenetic reconstruction and genetic approach. The analysis shows that proposed arguments cannot be considered as evidences for freshwater genesis of this taxon. Real facts and theoretical substantiations of early freshwater Salmoniformes are absent, so there is no need to prove that they acquired freshwater dwell in the Cretaceous-Paleocene in order to become anadromous fish again in the Eocene.

255-267 599
Abstract

Dynamics of the pacific salmon landing is reviewed. Mean registered domestic catch of these species was about 175,000 t per year in 1925–2021, but taking into account other estimations, as the volume of Japanese fishery, at least 250 . 103 t of salmon spawned in the Russian waters (within present-day borders) were withdrawn annually in this period. The potentially maximum annual catch of the Russian-originated pacific salmon is estimated around 350 . 103 t. Under current conditions for the Russian fishery, the annual catch of pacific salmon is unlikely to be less than 140–150 . 103 t in low-productive years and less than 220–250 . 103 t in high-productive years. For the next decade, annual catch of pacific salmon will supposedly exceed these thresholds in 100–120 . 103 t.

268-282 319
Abstract

Importance of fish species in the benthal ichthyocoenoses (up to depths of 2000 m) is discussed for the Russian waters in the Far-Eastern Seas and adjacent North-West Pacific on the data of bottom trawl surveys conducted by Pacific Fish. Res. Inst. (TINRO) in 1977–2010. The inverse Simpson index (or polydominance index) was chosen as a measure of dominance; Sorensen-Chekanovsky similarity index was used for comparative analysis of the dominance structure in ichthyocoenoses. The importance is determined for the top 20 species ranked by biomass (94.9 % of the total biomass of all demersal fish on the shelf and 95.8 % — at the continental slope, on average). Poor evenness under strong domination of 2–4 species is noted in the fish communities within the range of 0–2000 m. Walleye pollock Theragra chalcogramma dominate in all regions whereas the subdominants are pacific herring Clupea pallasii, pacific cod Gadus macrocephalus, atka mackerel Pleurogrammus monopterygius, or okhotsk atka mackerel P. azonus, depending on the region. The pollock domination is interrupted at the continental slope of the Bering Sea, where giant grenadier Albatrossia pectoralis dominate. The subdominants at the continental slope of all regions are greenland halibut Reinhardtius hippoglossoides matsuurae, popeye grenadier Coryphaenoides cinereus, pacific herring, pacific sleeper shark Somniosus pacificus, scale-eye plaice Acanthopsetta nadeshnyi, and blackfin flounder Glyptocephalus stelleri. Generalized graphs of the ichthyocoenoses similarity between the studied regions (Okhotsk Sea, Bering Sea, Japan Sea, and Pacific waters at Kamchatka and Kuril Islands) by species structure and composition of the dominant species are presented, separately for the shelf and continental slope.

283-304 341
Abstract

Biological characteristics and dynamics of stocks and fishery are considered for pacific herring in the South-Kuril fishing district on the data of research surveys and fishery statistics for 2014–2021. Features of the herring wintering and the rates of linear growth and maturation are analyzed. The stock recovery on the shelf of southern Kuril Islands is detected that corresponds to recovery of the whole Sakhalin-Hokkaido population of this species. A sharp increase of the herring abundance in this area is observed nowadays for the first time since the 1940s. According to results of cohort modeling, the commercial biomass of herring in the South-Kuril district has increased from several tens of ton in 2014–2017 to 9,700 t in 2021. The basis of the stock consists of fish aged 3–4 years, 25–29 cm long, that prevailed (76–82 %) in the catches in 2020–2021. The stock increasing is accompanied by expansion of the herring distribution, the aggregations density increasing in spring, complication of the size and age structure, heightening of the average size and age in catches of fixed nets in the spawning season, mass appearance of the juveniles in catches of bottom trawl survey in 2020, and progressive growth of the landing in 2018–2021. The usual place for the herring wintering in this area is the eastern side of the deep-water canyon off the western coast of Kunashir Island. According to updated data, the spawning migrations of herring begin in early-middle April. The producers migrate mainly from the wintering sites to the southern Kunashir Strait, and then along the Pacific side of Kunashir Island to their spawning grounds. The migration along the Okhotsk Sea coast is secondary. The spawning occurs at Kunashir Island in the period from late April to middle May (the timing varies from year to year; the peak of spawning was observed in early May in 2020, but in middle May in 2021). Unlike other populations, the herring of the South-Kuril area do not make extended migrations after the spawning, but feed on adjacent shelf for a long time. Fishery on herring develops rapidly in the South-Kuril fishing district: the annual catch was 140 t in 2018, but reached 1010 t in 2021. Trawl fishery of pacific herring has the highest prospects for coming years. The fishing by Danish seines can be intensified in the waters between Kunashir and Shikotan in the pre-spawning period, though the landing by fixed nets on the spawning grounds can be stabilized if the number of coastal fishing teams will be increased.

305-315 541
Abstract

The shift in strontium (Sr) concentrations in fish otoliths is a commonly used proxy for identification of marine environment entry during diadromous migrations. However, there is still controversy about the appearance of the Sr-based sea entry mark relative to the true point of entry. In this study, the Sr signal lag was assessed in otoliths of juvenile sockeye salmon (Oncorhynchus nerka) under experimental conditions replicating the transition to seawater during juveniles’ seaward migration. A Sr signal delay was observed to average at 8.2 (SD = 5.1) days for fish with a body length of 140–170 mm (and a weight of 30–70 g). This lag may be species-specific and should be taken into consideration when estimating marine entry timing and marine residence duration of juvenile salmon.

316-328 335
Abstract

Catch distribution and size-age structure of walleye pollock in the Chukchi Sea are considered on the data obtained in surveys conducted by TINRO in 2018–2020. The age of pollock was determined by otoliths. Two age groups were presented in the catches: the first group of juveniles and 1-year old fish and the second group of 7–22-year old fish, mostly 8–15 years old (90 %). The fish of 3–6 year old were absent in the catches. This age structure suggests that the stock is formed by the fish migrated from the northern Bering Sea. However, the backward migration is doubtful; the pollock, once migrated to the Chukchi Sea, remain in this new habitat, as could be seen from the age-length dependence for a part of the stock distinguished by lower growth rate because of dwelling in severe conditions of this area. Aggregations of the fast-growing (just migrated from the Bering Sea) and slow-growing (local residents) pollock had different distribution patterns in the surveyed area in the southwestern Chukchi Sea. The fast-growing allochthonous pollock distributed widely, including the seaward waters, whereas the resident pollock preferred the coastal waters. The walleye pollock fishery has started in the southern coastal area of the Chukchi Sea in 2021, so the resident stock is exploited mainly.

329-331 286
Abstract

For the first time, natural entry of ayu or sweetfish into the river of Peter the Great Bay basin (Japan Sea) and generally into the waters of Russian Federation is registered. This finding extends the list of fish species and families dwelling in the Russian waters. 

332-342 316
Abstract

State of the blue crab stock and production is considered for the Russian sector of the Bering Sea on the data of bottom trawl and trap surveys conducted by TINRO in 2005–2017 and fishery statistics. The commercial stock was assessed for 2018 by cohort analysis. The absolute majority of commercial males within the West Bering Sea fishing zone concentrated in two areas located at Koryak coast and at Cape Navarin, whereas the commercial aggregations were absent in the Olyutorsky Bay and Karaginsky Bay. The stock distribution between these two areas was unstable; recently the aggregation at Koryak coast increased to 72 % of the total number of commercial males in 2017. This dynamics is conditioned by both changes in reproduction and intensity of fishery. The total commercial stock of blue crab had increased since 2014 and reached the maximum of 18.133 × 106 ind. (males) in 2017 that exceeded significantly the level of 2005–2013. The blue crab fishery extends in the Bering Sea, since 2010 the portion of used TAC increased from approximately 93 % in 2011–2015 to 98 % in 2016–2017 and 99 % in 2018. State of the population is evaluated as satisfactory and stable.

343-350 238
Abstract

Spawners of sockeye salmon caught in northern Iturup and in the Prostor Bay and Kurilsky Bay in July-August, 2021 are investigated. Almost all of them had the age 1.2+ or 1.3+, with prominent prevalence of the former both for females (88.9 %) and males (80.0 %); other age groups had symbolic representation. Older individuals of both sexes were significantly larger. The sockeye of Iturup Island spend only 2 years in the sea, so both females and males are smaller by weight than the producers of other sockeye herds in the Russian Far East. The short puberty is supposedly favorable for formation of relatively abundant stock of artificial reproduction by the sockeye of Iturup Island.

351-368 256
Abstract

State of the spawning part of the sockeye salmon population in Lake Nachikinskoye is characterized. Adults of the early race enter the lake from the sea in spring and early summer, mature at a depth and spawn from July to late August in three different loci — creeks, springs and lake, forming the corresponding ecotypes. The late race representatives enter the lake in July-August, mature, and spawn until December in the same loci. The races differ in age structure, size and fecundity. Males dominate in both races, with a growing proportion of small-sized individuals. According to the materials of aero surveys, the number of fish on the spawning grounds decreased gradually until 2016. Recent data are presented for the number of sockeye salmon belonged to early and late races on certain spawning grounds in the lake basin, based on results of quadrocopter surveys in 2018–2021. The number of the early race spawners was ~100–400 × 103 ind., late race ~300–500 × 103 ind.; the fluctuations were not synchronous between the races. These great spawning stocks require reliable protection and detailed annual monitoring to predict further changes.

369-389 312
Abstract

Interannual changes of the pink salmon abundance at the western and northeastern coasts of Kamchatka are analyzed. Local stocks with certain patterns of the abundance dynamics are revealed. Contribution of these local groups to the overall reproduction of the regional macro-complexes and catch of pink salmon in the 1957–2020 is considered. Prospects of the reproduction and catch are evaluated. Taking into account the revealed heterogeneity of the population dynamics in spatially isolated groups within macro-complexes, quality of forecasting the pink salmon stocks and catches at Kamchatka could be improved.

ENVIRONMENTS OF FISHERIES RESOURCES

390-408 313
Abstract

Significance of larvaceans (class Appendicularia) for plankton community and feeding of nekton in the Far-Eastern Seas and North Pacific is underestimated, this group of species is poorly represented in scientific literature. The total biomass of larvaceans is below the stocks of dominant groups in the large-sized zooplankton, as copepods, euphausiids, arrowworms, amphipods, and coelenterates, but accounted together with their shells (called «houses») they form a comparable stock. In the studied area, the class Appendicularia is represented by four species: widely distributed Oikopleura vanhoeffeni, O. labradoriensis, and Fritillaria borealis and F. sp. (perhaps F. pacifica) in the southern periphery of this area. Larger and more numerous oikopleurids dominate by both abundance and biomass and are presented in all size fractions of zooplankton, whereas fritillarids are presented mostly in the small-sized fraction. Larvaceans distribute mainly in the upper epipelagic layer (55–97 %), i.e. in the layer of their prey concentration; their density is the highest in the coastal zone with the depth < 50 m and decreases in deeper areas. They are a significant portion in the diet of many nekton species (41 out of 151 species in the Trofology database of TINRO), including basic commercial fishes, as pollock, salmons, herring, polar cod, mackerels, sardine and some others. Their mucus houses glowing at night, with the animal inside, whose tail vibrates constantly providing movement and nutrition, are attractive for many plankton-eaters. Appendicularia have a high occurrence in the food of all size-classes of nekton, though it decreases for larger-sized fish of such mass fish species, as walleye pollock and pink and chum salmons.

409-413 240
Abstract

Cabbeling due to mixing of the surface waters from the Bering Strait and the Chukchi Sea is evaluated quantitatively and variations of its impact on seasonal and climatic scale are analyzed. The cabbeling effect increases additionally the mixed water density in 0.059 kg/m3 in summer and in 0.001 kg/m3 in winter. Seasonal variation of the cabelling repeats the seasonal variation of temperature difference between the interacted water masses (ΔT ~ 5,0 оC in summer, ΔT ~ 0,5 оC in winter). This process provides additional energy for sinking of warm and salt mixed water in summer, when it penetrates far into the Arctic. In winter, the temperature difference between the mixing waters is about zero, so the cabbeling almost disappears. Both temperature and salinity have climatic trends in the Chukchi Sea that causes the climate-scale variation of the cabbeling: its impact increases in 0.002 kg/m3 per decade in summer because of climatic heating (~0,13 оC/decade) and salinity decrease (~0.04 psu/decade).

PROMRYBOLOVSTVO

414-428 324
Abstract

Chub mackerel and japanese sardine fishery is overviweved for the period since 1976. Two blooms of high abundance were observed within this period for both species. Effectiveness of fishing methods used during the past and the present blooms is compared to reveal prospects for their improvement and to sunstantiate the operating parameters of fishing gear suitable for energy capabilities of fishing vessels with certain tonnage. On results of this analysis, wider use of purse seine is recommended for landing of japanese sardine, as the more effective and resource-saving technology. The fish could be poured from the seine by either coupler or fish pump; the fish pump is recommended for trawl vessels, as well.

METHODS OF INVESTIGATIONS

429-449 497
Abstract

Methodology for photogrammetric counting of pacific salmon by means of unmanned aerial vehicles (UAVs) of consumer grade is developed. The spawners and spawning redds are counted using photogrammetric processing of aerial images taken by UAVs at monitoring sites. The photogrammetric products (orthomosaics and digital elevation models — DEMs) are analyzed in geographic information systems (GIS). The estimations of relative abundance for the monitoring sites are extrapolated to entire area of potential spawning grounds. There is shown for the first time that DEMs of water channels allow to visualize and count the redds. Detailed description of methodology is presented, including the survey planning and implementation, data processing, fish abundance estimation, data analysis and visualization, and web-publication. Recommendations for choosing UAV, its accessories and software for flight, photogrammetry and GIS are provided. This approach will facilitate objectivity of salmon counts and provide gradual transition from subjective aerovisual methods towards proven and verified digital basis of fish abundance assessment.

450-465 296
Abstract

Experiments on comparing the methods for assessment of Saccharina japonica commercial stock were conducted in 2021. In total, 11 sites in the northwestern Tatar Strait southward from the Sovetskaya Gavan Bay, along the 44 km stretch of coastline between Cape Krasny Partizan (48о58′ N 140о23′ E) and Cape Korovin (48о37′ N 140о11′ E), were surveyed aboard RV Ubezhdenny and small boats. This is a traditional area of Saccharina japonica commercial harvesting. Four methods were compared: 1) visual assessment of projective cover from the sea surface by two observers independently; 2) assessment of projective cover by two observers independently on the images obtained from a remotely operated underwater vehicle (ROV); 3) estimation of projective cover by a diver; and 4) assessment on the data of quantitative diving samples. The former three methods are comparable and differ by 1.2–1.7 times. The estimates made by the latter method of diving sampling exceed them by 2.4–4.1 times because of artifacts specific to this method. To eliminate inaccuracies, diving samples should be collected under control from the sea surface by ROV. Evaluation of the projective cover by diver is inadvisable. Visual assessments of the projective cover from the sea surface are simple and cheap but inconvenient for documentation. The stock assessment with micro-ROV is recognized as the optimal method provided an adequate accounting of the kelp abundance and complete documenting of the survey materials.

466-497 428
Abstract

State of the greenland halibut stock in the Sea of Okhotsk fishing zone is evaluated as overfished with a high probability of 97.5 % by the index of fishable biomass, and the overfishing continued in 2021. This conclusion is based on results of double filtering the posterior parameter estimates in the state-space generalized surplus production model JABBA (Just Another Bayesian Biomass Assessment), with additional tuning of the new model taking into account these results. The overfishing was not caused by significant changes of environmental parameters (average SST and EOF modes of SST were examined), but its main reason was the overestimated target harvest rate established for the Far East of Russia as 10 % of the total biomass or a half of natural annual mortality (20 %). This incorrect value of the rate was based on incorrect determination of age structure and terminal age for the halibut by the fish scale method. The new approach of the stock status evaluation with JABBA model is independent on the age data. It includes the additional filtering of the JABBA model result, its refinement with stringent tuning using the algorithm of No-U-Turn sampler, and checking additional parameters on hyperstability or hypersensitivity. The new reference point of the target harvest rate is between 2.5 and 5.4 % (95 % credible interval) of the total biomass, with a median of about 3.75 %. This new value is slightly higher than that one used by ICES for greenland halibut in the northeastern Atlantic (3.5 % for fishable biomass, its reduction to 2.5 % is discussed), but these values cannot be compared because of different habitat conditions and probably different growth rate of greenland halibut in the Okhotsk Sea and the Atlantic. Researches on the optimal level of greenland halibut exploitation should be continued; anyway, the new reference point of the target harvest rate has to be implemented immediately and to be used at least until correction of the age-length key for greenland halibut in the Okhotsk Sea. The input data and Stan code of the new model are presented in the annexes.



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ISSN 1606-9919 (Print)
ISSN 2658-5510 (Online)