Pollock Stock Research Articles

The Long-Term Dynamics of Walleye Pollock Stocks in Relation to Oceanographic Changes in the East Sea

The decline in walleye pollock (Gadus chalcogrammus) stocks in Korean waters is a major concern for fishery conservation and management. However, the causes and mechanisms of this collapse remain unclear. This study investigated the complex dynamics influencing the abundance of walleye pollocks in the East Sea of Korea over several decades, by analyzing data from long-term changes in biological factors including composition of length and sex, catch, and oceanographic condition. Prior to the mid-1980s, the catch ratio of juveniles was higher than that of adults, with a higher proportion of females in both juvenile and adult catches compared to males. Especially, high fishing pressure on female individuals can be an important factor contributing to declining reproduction. Consequently, after the mid-1980s, there was a sudden decline in juvenile pollock catches. In the late 1980s, there was a rapid increase in sea surface temperature (SST) in the spawning grounds, resulting in a decrease in both the duration of suitable temperature for spawning and the regional proportion for suitable spawning conditions. Consequently, the decline in pollock stocks after the late 1980s due to overfishing of pollock in the mid-1980s was further exacerbated by the effects of SST warming after the late 1980s. These findings highlight the impact of overfishing and environmental factors on pollock stocks and indicate the need for appropriate fishery management practices to ensure the sustainable use of fishery resources.

Variability of stock status walleye pollock fishery

The analysis of the variability of walleye pollock stocks assessment and fisheries showed that in most areas the degree of exploitation is at a low level (4,7–13,5%), with the exception of the Navarinsky region of the Bering Sea, the coast of eastern Kamchatka, the northern Kuril Islands and western Sakhalin (16,7–18,9%). Climate change has a significant impact on the of walleye pollock stocks assessment. Positive anomalies of the PDO climate index (Pacific Decadal Oscillation) create favorable conditions for northern populations, whereas for southern populations living on the southern border of the area, on the contrary, those periods when negative anomalies are noted are more comfortable. Subject to the implementation of the cooling scenario in the North Pacific Ocean, walleye pollock biomass centers may shift to the southern regions (the economic zone of the DPRK), which will lead to a significant reduction in catches in the economic zones of the Russian Federation and the United States, which are currently the main players in the walleye pollock market.

Assessment of spawning stock for walleye pollock <i>Gadus chalcogrammus</i> Pallas, 1814 in the northern Okhotsk Sea by ichthyoplankton method taking into account the eggs mortality

A new approach for assessment of the spawning stock of walleye pollock in the northern Okhotsk Sea on the data of ichthyoplankton surveys is proposed. To estimate the actual number of spawned eggs, average age of eggs at each stage of development was determined and the eggs mortality was estimated in dependence on age. For the spring ichthyoplankton surveys in 2019–2023, the eggs mortality was evaluated as 27 % for stage I, 57 % for the stage II, 74 % for the stage III, and 86 % for the stage IV – these portions of the spawned eggs were not caught and counted. So, the number of counted eggs was in 1.7–2.1 times lower that the actual number of spawned eggs. The spawning stock biomass was amounted as 12.9 . 106 t in 2019–2023, on average, on the base of the actual number of eggs determined taking unto account the eggs mortality (while the biomass calculated from the counted number of eggs only would be 6.9 . 106 t). Results of the spawning stock estimation with this new method are comparable with the stock assessments by trawl surveys. The eggs number correction through mortality is recommended for calculation of the spawning stock for walleye pollock in the Okhotsk Sea using the ichthyoplankton method.

Winter-autumn fishery of walleye pollock <i>Gadus chalcogrammus</i> (Gadidae) by bottom gill nets in the Kunashir Strait in 1999–2022

Japanese gill net fishery of walleye pollock in the Kunashir Strait, also well-known as local spawning grounds of this species, has been carried out in the eastern (Russian) part for more than 20 years. The results of the fishery allow us to consider general trends in the long-term changes of the local stock in mentioned dynamic and still underexamined area on the border of the Sea of Okhotsk and the Pacific Ocean. The use of a large series of standardized catch per effort as an index of stock biomass indicates specific dynamics of walleye pollock stock biomass in the Kunashir Strait, different from the behavior in the adjacent ocean waters of the southern Kuril Islands. On the background of a long-term trend of decreasing catch per effort in the Kunashir Strait, the CPUE in the ocean waters of the islands, as well as in the southern part of the Sea of Okhotsk, demonstrates opposite trend of increase of this parameter.

Modern status, formation and exploitation of walleye pollock stocks off the southern Kuril Islands

The aim of the study is analyze the state and clarify modern status of walleye pollock stocks in the southern Kuril Islands waters.Result: Strong year-classes are revealed, which determined pollock stock dynamics in the South Kuril region in the 2010s — e arly 2020s. It is shown, that the maximum pollock biomass since the early 1990s was observed in the early 2010s, and in the early 2020s decreased to the average level. The organization of fishing and the composition of pollock commercial catches off the southern Kuril Islands are differ at low and high levels of stocks.Novelty: New data on structure and pollock stocks assessment in the South Kuril region since 2011 based on the integrated surveys results are presented. Long-term data on the effectiveness of fishing and the structure of pollock commercial catches in the South Kuril zone are considered.Practical significance: The obtained estimates of the current state and structure of pollock stock will be used for short-term and long-term forecasts.Research methods: walleye pollock stocks assessment in the South Kuril region is based on the annual integrated research expeditions in accordance with the standard methods used in TINRO to monitor pollock stocks.

Reproduction, stocks assessment and walleye pollock fishery in Navarin area of the Bering Sea

The aim of the work is to summarize information about the reproduction, stock dynamics and walleye pollock fishery in the Navarin region of the Bering Sea.Methods used: methods and models of the fishery science, allowing to assess the state of the stock in conditions of increased data noise and specific features of the entry of generations into the fishing stage.Result: the updated estimates of walleye pollock stock status in the Navarin region of the Bering Sea are given. The available data allow us to state that in this area of the Bering Sea there are reproductively isolated groups of winter and spring spawning walleye pollock.Novelty: it was shown that trends in the biomass dynamics of walleye pollock spawning stock in the Navarin region and the East Bering Sea stock changed synchronously in 1995–2011 and in 2019–2021. While the rest of the time, synchrony was not observed. According to the calculated data, it is expected that the biomass values may coincide for the first time in 2022.Practical significance: the results obtained provide additional grounds for refining the volume of TAC.

Walleye pollock of the Bering Sea: features of distribution and biology, stocks, fishery

The purpose of the work: to identify the features of the distribution and biology of walleye pollock Gadus chalcogrammus, as well as to provide information on the reserves and development of its resources in the Bering Sea.Methods used: to achieve the goal, data on distribution, biology, biomass and fishery of walleye pollock were analyzed.Novelty: elements of novelty are generalized modern materials on the distribution, biology, stocks and fishery of walleye pollock.Practical significance: at the present stage, the East Bering Sea and northwestern pollock populations are at the average long-term level of biomass, their annual changes largely depend on the background conditions of the natural environment and the development of the food supply, which determine the scale of fish migration from the southeastern part of the Bering Sea to the northwestern and back. In the West Bering Sea walleye pollock, there is a trend towards a gradual recovery of stocks after a period of minimum values in the late 1990s — e arly 2000s. In general, the current state of walleye pollock stocks in the Bering Sea is characterized as stable, which maintains the fishery at a relatively high level. The results obtained in this work on the characteristics of the distribution and biology of walleye pollock, the state of its stocks and fishing will improve the efficiency of using the raw material base of marine fish in the Bering Sea.

Walleye pollock of the Okhotsk Sea: history of fishery and current status

The purpose of the workis to review the history of the development of walleye pollock stocks in the of Okhotsk sea, to analyze the fishery and the state of its stocks.Methods:literature data, materials of long-term surveys by VNIRO (1997–2002) on the walleye pollock spawning grounds of Western Kamchatka, as well as the R/V «Professor Kaganovsky» in the spring of 2022 were used. Fishery statistics of OSM Monitoring.Results:The maximum walleye pollock catch (0.91 million tons) in the North Sea of Okhotsk subarea was achieved in 1995. In the period 1998–2001 annual catches averaged 510 thousand tons, in 2002–2008 decreased to 210 thousand tons. Over the past decade, there has been a gradual increase in catch from 286 thousand tons in 2009 to 383 thousand tons in 2020. Pollock catches in the West Kamchatka and Kamchatka-K uril subzones after high fishery rates achieved in 1996–1997 (1.2 million tons), began to decline, falling in 2004 to 191 thousand tons, after which a tendency to their increase appeared. In the period 2016–2019 catches walleye pollock of East Okhotsk sea stabilized at the level of 617–618 thousand tons, in 2020 the catch amounted to 681 thousand tons. The walleye pollock stock in the East Sakhalin subzone is currently at a low level, its gradual recovery began in the mid-2000s in 2019–2020. its catch was 110 thousand tons.Novelty:New data on walleye pollock stocks in the Okhotsk Sea are presented. Based on the results of a trawl survey conducted in the spring of 2022, the total number of walleye pollock in the Okhotsk Sea was estimated at 56.043 billion ind., biomass — 13.497 million tons, while the commercial stock was estimated at 10.413 million tons and 21.964 billion ind. Maps of the distribution of adult walleye pollock and eggs in the Okhotsk Sea in the spring of 2022 are given.Practical significance:data on the status of walleye pollock stocks in the Okhotsk Sea will be used to prepare TAC materials, as well as recommendations for rational fishery.

Reproduction, stock status and fishery for walleye pollock in Peter the Great Bay in the modern period

The aim of the study is to analyze the current state of reproduction, resources and pollock fishery in Peter the Great Bay.Result: It is shown that the increase in pollock abundance is associated with the appearance of a strong yearclass of 2014 in Peter the Great Bay. Pollock biomass has increased significantly, mass spawning has resumed in traditional spawning areas, commercial catch of pollock increased to record levels. However, during the three spawning seasons of the year-class 2014 there was no significant recruitment, so the fish stock is expected to return to a low level.Novelty: The results of scientific research conducted in the Peter the Great Bay in 2019–2022 made it possible to obtain new data on the reproduction, current state and structure of pollock stock.Practical significance: The obtained estimates of the current state and structure of pollock stock will be used for short-term and long-term forecasts.Research methods: The data of research bottom trawl and ichthyoplankton surveys and pollock catch statistics from the Industry Monitoring System (OSM «Fishing») were used.

Condition and structure of pollock stock in the Sea of Okhotsk in 2011–2020

Purpose of the work: to assess the condition and structure of the pollock stock in the period 2011–2020 based on the materials of scientific surveys carried out in the main areas of its reproduction in the northern part of the Sea of Okhotsk. Methods used: data on the biology and fishing of pollock were obtained during scientific trawling surveys in the northern part of the Sea of Okhotsk in the spring period 2011–2020. The areal method was used to calculate the abundance and biomass. Recalculation of the size composition of pollock in the age is carried out using the size-age key. Novelty: the elements of novelty are the analysis of the structure and dynamics of the pollock stock according to trawl surveys, as well as its fishing in the northern part of the Sea of Okhotsk over a ten-year period. The yield level of pollock generations at the age of one year and the age of near replenishment of the spawning stock, which appeared during the 2010s, was determined. Result: despite the heterogeneity of the size and age structure of pollock in the considered fishing subzones of the Sea of Okhotsk, the presence of high-yielding generations is usually manifested for the entire northern part of the Sea of Okhotsk. The most significant fluctuations in pollock stocks were observed in the first half of the decade under review. During the 2010s, the trends in pollock catch in the North Okhotsk subzone and Kamchatka subzones coincided. The efficiency of pollock use in the northern part of the Sea of Okhotsk is characterized by maximum values. Practical significance: the results obtained on the dynamics and structure of the pollock stock in the North Okhotsk and two Kamchatka fishing subzones of the Sea of Okhotsk over a ten-year period will be used for prognostic purposes.

Walleye pollock (<i>Gadus chalcogrammus</i>, Pallas, 1814) fishery, size and age composition, state of stocks and catch prospects in the waters adjacent to Kamchatka peninsula and Northern Kuril Islands

The article provides data on the catch of the Northern Okhotsk, Eastern Kamchatka and Western Bering Sea walleye pollock stocks, fishery structure by the fishing gears in 2016–2019, size and age composition of the fish in the commercial trawl and Danish seine catches in 2010–2019. Data on the generation abundance and stock condition indices used in the stock assessment models are also demonstrated. Interannual dynamics of the total and spawning stock biomass, determinants of the dynamics and prospects of fishing are analyzed.

Концептуальная основа для разработки стратегий устойчивого использования водных биологических ресурсов на примере промысла минтая в дальневосточных водах России

The article proposed to discuss a concept of new strategy for the sustainable use of populations of aquatic organisms using as an example a fishery for Walleye Pollock in the Far Eastern seas of the Russian Federation. It is shown that the current regulations governing the impact of fishing contained in the Fishing Regulations do not quite consider changes related to the dynamics of pollock populations parameters. As a result, there is an uncontrolled and often negative impact of fishing, which leads to changes in the phenotypic and size-age structure of W. Pollock populations being fished, which ultimately affects the profitability of fishing. It is proposed to develop a separate strategy for each W. Pollock stock unit, which annually regulates the level of fishing impact, depending on the state of the stocks and market conditions. The proposed strategy concept makes it possible to regulate not only the allowable volume of catch, but also the size structure of catches, by changing the fishing parameters every year. It will keep the harvested stocks stable and will help to obtain the maximum possible fishing profitability.

Integrating seabird dietary and groundfish stock assessment data: Can puffins predict pollock spawning stock biomass in the North Pacific?

AbstractInformation on the annual variability in abundance and growth of juvenile groundfish can be useful for predicting fisheries stocks, but is often poorly known owing to difficulties in sampling fish in their first year of life. In the Western Gulf of Alaska (WGoA) and Eastern Bering Sea (EBS) ecosystems, three species of puffin (tufted and horned puffin, Fratercula cirrhata, Fratercula corniculata, and rhinoceros auklet, Cerorhinca monocerata, Alcidae), regularly prey upon (i.e., “sample”) age‐0 groundfish, including walleye pollock (Gadus chalcogramma, Gadidae) and Pacific cod (Gadus microcephalus, Gadidae). Here, we test the hypothesis that integrating puffin dietary data with walleye pollock stock assessment data provides information useful for fisheries management, including indices of interannual variation in age‐0 abundance and growth. To test this hypothesis, we conducted cross‐correlation and regression analyses of puffin‐based indices and spawning stock biomass (SSB) for the WGoA and EBS walleye pollock stocks. For the WGoA, SSB leads the abundance of age‐0 fish in the puffin diet, indicating that puffins sample the downstream production of the WGoA spawning stock. By contrast, the abundance and growth of age‐0 fish sampled by puffins lead SSB for the EBS stock by 1–3 years, indicating that the puffin diet proxies incoming year class strength for this stock. Our study indicates connectivity between the WGoA and EBS walleye pollock stocks. Integration of non‐traditional data sources, such as seabird diet data, with stock assessment data appears useful to inform information gaps important for managing US fisheries in the North Pacific.

Responses of a pelagic fish community to reduced fishing pressure in the central Bering Sea

Ecosystem-based fishery management (EBFM) requires minimizing the risk of irreversible change to a natural assemblage of species. Because pelagic fisheries modify the biotic community rather than the physical environment and often target migratory species, the pelagic community can be expected to respond quickly after fishing pressure is reduced. We monitored the pelagic zooplanktivore community over 4 decades in the central Bering Sea before and after the closures of large-scale pelagic fisheries. We found a quick and steep change in the pelagic fish community structure after fishing pressure was reduced, which reflected increased abundance of salmon species; however, walleye pollock stocks, one of the most valuable fisheries resources in this area, have not recovered. A lower population growth rate might contribute to the slow recovery of pollock stocks. Long-term ecosystem monitoring of fishing grounds and surrounding ecosystems will be required for successful implementation of EBFM of pelagic fish stocks.

Standardization of CPUE for walleye pollock in the Okhotsk Sea with inclusion of some environmental factors

Catch of walleye pollock by Russia is the highest in the northern Okhotsk Sea where on average 0.94 million metric tons were caught annually in the period between 1962 and 2017, or around 24 % of the total yield of Russian fishery. The total stock and spawning stock of pollock grow there since 2002, though the catch per unit effort (CPUE) has significantly decreased in the beginning of 2018 despite expected high levels of both total and spawning stocks. The sea surface temperature, ice cover and storms frequency were examined as possible reasons of low fishing efficiency in 2018. For this purpose, the generalized linear models (GLM) and generalized additive models (GAM) of catch dynamics are compared. GAM with addition of temperature and storms factors has the lowest Schwarz’s Bayesian criterion and the highest explained deviance (61.6 %). Efficiency of fishing gears has nonlinear relationship with the towing time. CPUE has hypersensitivity to the stock biomass presented as the power dependence (γ = 0.94, r = 0.923). Standardized CPUE is recommended for using in the final GAM for the pollock stock assessment in the northern Okhotsk Sea, hypersensitivity of CPUE should be estimated and corrected if necessary.

Practical Application of a Bioenergetic Model to Inform Management of a Declining Fur Seal Population and Their Commercially Important Prey

Food availability is a key concern for the conservation of marine top predators, particularly during a time when they face a rapidly changing environment and continued pressure from commercial fishing activities. Northern fur seals (Callorhinus ursinus) breeding on the Pribilof Islands in the eastern Bering Sea have experienced an unexplained population decline since the late-1990s. Dietary overlap with a large U.S. fishery for walleye pollock (Gadus chalcogrammus) in combination with changes in maternal foraging behavior and pup growth has led to the hypothesis that food limitation may be contributing to the population decline. We developed age- and sex-specific bioenergetic models to estimate fur seal energy intake from May–December in six target years, which were combined with diet data to quantify prey consumption. There was considerable sex- and age-specific variation in energy intake because of differences in body size, energetic costs, and behavior; net energy intake was lowest for juveniles (18.9 MJ sea-day–1, 1,409.4 MJ season–1) and highest for adult males (66.0 MJ sea-day–1, 7,651.7 MJ season–1). Population-level prey consumption ranged from 255,232 t (222,159 – 350,755 t, 95% CI) in 2006 to 500,039 t (453,720 – 555,205 t) in 1996, with pollock comprising between 41.4 and 76.5% of this biomass. Interannual variation in size-specific pollock consumption appeared largely driven by the availability of juvenile fish, with up to 81.6% of pollock biomass coming from mature pollock in years of poor age-1 recruitment. Relationships among metabolic rates, trip durations, pup growth rates, and energy intake of lactating females suggest the most feasible mechanism to increase pup growth rates is by increasing foraging efficiency through reductions in maternal foraging effort, which is unlikely to occur without increases in localized prey density. By quantifying year-specific fur seal consumption of pollock, our study provides a pathway to incorporate fur seals into multispecies pollock stock assessment models, which is critical for fur seal and fishery management given they were a significant source of mortality for both juvenile and mature pollock.

Large copepods as leading indicators of walleye pollock recruitment in the southeastern Bering Sea: Sample-Based and spatio-temporal model (VAST) results

In the southeastern Bering Sea, years with above-average sea ice extent have been associated with elevated abundances of large lipid-rich copepods in both net tows and age-0 walleye pollock (Gaduschalcogrammus) diets, followed by high overwinter pollock survival and stronger recruitment into the fishery three years later. In this study, we directly compare large copepod abundances of taxa important in age-0 pollock diets (Calanus glacialis/marshallae, Metridia pacifica and Neocalanus spp.) to age-3 pollock abundance from stock assessments for year classes 2002–2015 (excluding 2013). Copepod samples from bongo nets were collected on fishery oceanography surveys in late summer during warm (low ice) and cold (high ice) climate stanzas. In addition to mean estimates of large copepods among stations (sample-based), we implemented a spatial delta-generalized linear mixed model using the Vector Autoregressive Spatio-Temporal (VAST) package to account for variations in survey coverage among years. Positive significant linear relationships were found for both of these estimates of large copepods during the age-0 year and the abundance of these pollock at age-3. Correlations were stronger using VAST model-based indices compared with sample-based indices (R2 = 0.74 versus 0.43, respectively, all copepod taxa combined). A significant relationship was also observed between the bottom cold pool (< 2 °C) area (indicative of sea ice coverage in the prior winter) during the age-0 year and subsequent age-3 pollock abundance (R2 = 0.56) and recruits per spawner, (ln(age-3 abundance /spawning stock biomass), R2 = 0.77). Consequently, the large copepod index or cold pool index may be used to predict future recruitment success of pollock three years in advance. Results provide support for the revised oscillating control hypothesis that suggests as the climate warms, reductions in sea ice and consequent reduced availability of ice-associated algae, an early spring food source, could be detrimental to large copepods and recruitment of the pollock stock in the region.

Adapting to climate‐driven distribution shifts using model‐based indices and age composition from multiple surveys in the walleye pollock (Gadus chalcogrammus) stock assessment

AbstractThe northern Bering Sea is transitioning from an Arctic to subarctic fish community as climate warms. Scientists and managers aim to understand how these changing conditions are influencing fish biomass and spatial distribution in this region, as both are used to inform stock assessments and fisheries management advice. Here, we use a spatio‐temporal model for walleye pollock (Gadus chalcogrammus) to provide two inputs to its stock assessment model: (a) an alternative model‐based biomass index and (b) alternative model‐based age compositions. Both inputs were derived from multiple fishery‐independent data that span different regions of space and time. We developed an assessment model that utilizes both the standard and model‐based inputs from multiple surveys despite inconsistencies in spatial and temporal coverage, and we found that using these data provide an improved spatial and temporal scope of total pollock biomass. Age composition information indicated that pollock density is increasing and moving farther north, particularly for older pollock. We found that including an index of cold pool extent could be used to extrapolate pollock densities in the northern Bering Sea in unsampled years. Stock assessment parameter estimates were similar for standard and model‐based input. This study demonstrates that spatio‐temporal model‐based estimates of a biomass index and age composition can facilitate rapid changes in stock assessment structure in response to climate‐driven shifts in spatial distribution. We conclude that assimilating data from regions neighboring standard survey areas, such as the Chukchi Sea and western Bering Sea, would improve understanding and management efforts as fish distributions change under a warming climate.

Multispecies biomass dynamics models reveal effects of ocean temperature on predation of juvenile pollock in the eastern Bering Sea

AbstractWalleye pollock (Gadus chalcogrammus) supports one of the largest commercial fisheries in the world. Juvenile pollock are important forage fish in the eastern Bering Sea (EBS) ecosystem, often representing the largest fraction in the diets of major Bering Sea piscivores. Large variability in the EBS pollock stock biomass in recent years has been attributed primarily to fluctuations in recruitment. It has been hypothesized that predation rates on forage fishes increase when the cold pool (a body of cold water &lt; 2°C) is extensive and covers much of the middle continental shelf, which tends to concentrate larger predatory fishes in the outer shelf and slope regions. In contrast, young pollock appear to tolerate colder temperatures than older fish and can stay in the cold pool, thereby reducing predation. We used a multispecies modeling approach to examine the effects of the cold pool size on predation of juvenile pollock. We found that predation on age‐1 pollock by age‐3+ pollock decreased, and predation on age‐1 and age‐2 pollock by arrowtooth flounder increased with increasing bottom temperature, which was used as a proxy for the cold pool size. These results suggest that the cold pool creates spatial separation between juvenile pollock and arrowtooth flounder, but not between adult and juvenile pollock. The model developed in this study could be used to examine the effects of other covariates on interspecific interactions, help explain observed changes in fish communities, and understand implications of climate change on ecosystems and their productivity.

RECENT CHANGES IN THE OKHOTSK SEA ECOSYSTEM (2008–2018)

Recent changes of the main oceanographic, chemical, and biological parameters of the Okhotsk Sea ecosystem are considered briefly for the last decades (2000–2010s), mostly on the data obtained in marine expeditions conducted by Pacific Fish. Res. Center (TINRO) annually. Since the mid-2000s, anomalous oceanographic conditions were formed there with prevailing heightened temperature in all layers of the sea and lowered ice cover caused by changes in the atmosphere circulation with northward shift of cyclones tracks in winter and weakening of winter monsoon. The ice cover was below the normal value every year since 2004. In the warmer winter conditions, producing of the high-density water on the northern shelf decreased from 3.2–7.8 . 103 km3 in 1998–2002 to 1.2 . 103 km3 on average in 2004–2015, and the water with density sq &gt; 26.8 was not formed at all in 2007–2009, 2011, and 2014–2015. As the result, winter convection, including the slope convection, became weaker and shallower and ventilated worse the water column, so dissolved oxygen content decreased in the lower portion of the intermediate layer, usually ventilated by slope convection. For the core of the intermediate layer (isopycnal surface 27.0 σθ), positive trend of temperature is estimated as +0.04…+0.16 o/decade, by areas, while the trend of dissolved oxygen content is negative: –0.07…–0.14 mL/L.decade, by areas. From the other hand, spring phytoplankton bloom became less intensive, presumably because of poorer upward flux of nutrients in conditions of weaker vertical mixing, and zooplankton biomass decreased, particularly for phytophages. However, these changes did not cause significant response in fluctuations of stocks for the main commercial fish and crab species. The largest stock of walleye pollock had cyclic fluctuations driven mostly by intra-population regulations, the stocks of pacific herring were rather stable, and the stocks of deep-water fish species, as flounders and halibuts had a slight tendency to growth, possibly because of better conditions for reproduction. Indeed, the densest aggregations of greenland halibut shifted from the depth of 600–700 m to 500–600 m that may be caused by de-oxygenizing of the lower portion of the intermediate layer. Crabs abundance also had positive dynamics obviously because of the effect of protective measures for red king crab in the 2009–2012, though its biomass continued to grow even after restoring the commercial landings. There is concluded that recent changes in the macroecosystem of the Okhotsk Sea correspond to the conception of the sub-polar ecosystems transformation under climate warming toward decreasing of their productivity and increasing of their functioning efficiency that was proposed earlier for the Japan Sea. Thus, from position of commercial exploitation of marine biological resources, the modern reconstruction of the Okhotsk Sea ecosystem under the climate change impact could be considered as a positive process.