Papers by Vladimir Radchenko
The early marine life period of Pacific salmon is considered to be critical for the formation of ... more The early marine life period of Pacific salmon is considered to be critical for the formation of their broodline numbers (Watanabe 2000). However, for a long time, this period was not investigated with research efforts concentrated in the offshore zone of far-eastern seas. It was believed that juveniles of the Sakhalin pink salmon stocks did not stay in the coastal zone for a long time. Migrations of 5–20 miles and more were thought to occur from the coast during the first days (Shershnev et al. 1982). In 2002, SakhNIRO began a study of juvenile salmon in the Sakhalin-Kurile region from the board of R/V Dmitry Peskov. Since 2003, a pelagic trawl (54.4/192 m) with the fine mesh size insert in the codend was used to catch salmon. The net fished in an area of 0.17 km 2 during one half-hour. Calculations of juvenile pink salmon abundance were executed by the squares method assuming a trawl catch-ability coefficient of 0.1 for such small fish. During June–July of 2002–2003, 337 trawl hau...
Technical Report
Winter surveys to the Gulf of Alaska in 2019 and 2020 examined the winter ecology of Pacific salm... more Winter surveys to the Gulf of Alaska in 2019 and 2020 examined the winter ecology of Pacific salmon, a season and location about which little is known. Coho salmon Oncorhynchus kisutch were mostly found in the southern areas of the Gulf of Alaska south of 52 o N where they appear to be in deeper water during the day. They were the second most abundant species of Pacific salmon indicating that most populations move off the shelf to spend the winter in the offshore areas covered by the surveys. Coho salmon from the Strait of Georgia and Puget Sound remained closer to shore off the west coast of British Columbia. These results indicate that large aggregations of mixed populations that are not associated with other species of Pacific salmon may form in the winter. The large schools may be associated with finding prey to maintain metabolic requirements as growth during the winter was minimal. The period of rapid growth started about late March to early April and may be associated with the appearance of large abundances of squid.
Technical Report
Abundant mesopelagic fishes play an important role in the trophic structure of the ocean pelagic ... more Abundant mesopelagic fishes play an important role in the trophic structure of the ocean pelagic fish community, both as zooplankton consumers and as a prey for predatory species. Since they mainly consume smaller planktonic prey than the most of commercially significant fish species and can be eaten by them, lanternfish (myctophids) provide an energy and matter transport from the small-sized part of planktonic community to the upper trophic layers. Myctophids and other small-sized mesopelagic fish are a common food of salmon, cods, sea perches, squid, and many cetaceans and seals (
Environmental Biology of Fishes
Technical Report
Winter is a highly important time in Pacific salmon (Oncorhynchus spp.) marine life, first, due t... more Winter is a highly important time in Pacific salmon (Oncorhynchus spp.) marine life, first, due to its duration. If we consider winter to be the four months from December to March in the latitude range of Pacific salmon ocean migration, it makes up from one-third to one half of the ocean residence time for pink O. gorbuscha and coho O. kisutch salmon originated from the marginal seas' basins. Some researchers consider winter as a critical period for Pacific salmon, likely due to a general feeling of inconvenience and danger associated with the stormy ocean environment, low water temperatures, significant decreases in forage fish and zooplankton biomasses in the upper pelagic layer that imply limited food availability. Physiological studies revealed salmon growth slowing and lowering of muscle lipid content (Naydenko et al. 2016). The ocean distribution of salmon is complex and variable, depending on spatio-temporal scale and synergies among heredity, environment, population dynamics, and phenotypic plasticity (Myers et al. 2016). Recently, new information was collected in scarcely studied regions and seasons, and summary reviews were published on the marine life phase of Pacific salmon (
Ecosystem Objectives and Indicators 1. Ecosystem-level and community-level conservation threshold... more Ecosystem Objectives and Indicators 1. Ecosystem-level and community-level conservation thresholds are relatively new ideas in marine conservation. Since they will require new kinds of indicators, research is needed for their development and application to the Bering Sea. 2. New research is needed to understand how to synthesize the large set of Bering Sea data records into a reasonable number of ecosystem status indicators. 3. A formal process of evaluating and selecting ecosystem indicators is a general requirement. The Alaska Fisheries Science Center should consider developing and applying such a process to the indicators in its Ecosystem Considerations appendix. 4. Enhancements to the ocean/ecosystem monitoring network are needed to fill data gaps at ecological pulse points (plankton, benthic infauna and epifauna, seasonal species interactions and movements, small pelagics, and cephalopods) to improve predictive models and the development of ecosystem indicators. 5. More collaboration between modelers at the Alaska Fisheries Science Center and the Pacific Marine Environmental Laboratory, and elsewhere is encouraged to link various climate/ecosystem and conservation/assessment models, and to use these models to evaluate management strategies. Socio-economics While the workshop did not address socioeconomic operational objectives for the Bering Sea and North Pacific, linkages between the well-being of people and healthy marine ecosystems require a level of attention comparable to those for ecosystem conservation objectives: 6. Socioeconomic objectives related with the marine environment should be developed for the region, along with their indicators and reference points. 7. The North Pacific Fishery Management Council should play a central role in shepherding the development of these socioeconomic objectives and indicators for the southeastern Bering Sea and Gulf of Alaska ecosystems; 8. There is a need to conduct scientific and policy analyses of pathways to achieve socioeconomic objectives while remaining within ecosystem-level conservation limits. Communication 9. Plans should be developed at an early stage on how the information from indicators can best be communicated to scientists, policy and decision makers, and the general public. The plans should include publishing concise, attractive executive summaries of major ecosystem status reports that will describe important trends and patterns in marine ecosystems for non-scientists. 10. To reach policy makers and the public in Asian countries, future iterations of the Synthesis chapter in the PICES North Pacific Ecosystem Status report should be published in multiple languages. 11. The development by the National Marine Fisheries Service of an Ecosystem Considerations website greatly increased access to time series of ecosystem indicators for the Alaska region, and should be maintained and enhanced. 12. An overview of the status of the Bering Sea ecosystem(s) should be presented at the annual Marine Science in Alaska Symposium to foster broader communication among the diversity of regional scientists, managers and the public. Specific recommendations from individuals/groups can be found under Discussion Group Results in this report. xi Foreword This project entitled "Integration of ecological indicators for the North Pacific with emphasis on the Bering Sea: A workshop approach" was developed from a proposal submitted in response to the North Pacific Research Board's (NPRB's) request for proposals for 2005, specifically Project Need 1, Item 2, as stated below: Evaluate the Utility of Ecosystem Indicators in Explaining Processes underlying Marine Production. Processes related to physical (e.g., atmospheric forcing, ocean temperature, salinity, sea level, freshwater discharges, transport of planktonic life history stages, sea ice extent and duration, turbulence and cold pool extent), chemical (e.g., nutrient/micronutrient availability to phytoplankton), and biological (e.g., predation, timing of plankton/zooplankton production, commercial catch composition, biomass/abundance trends) phenomena provide indicators of ecosystem status. The project would report on the current understanding of ecosystem indicators in the Bering Sea and Aleutian Islands, evaluate pros and cons of existing indicators, and identify next steps toward developing and/or validating indicators and evaluating their performance (e.g., using hind-casts of indicators and various marine populations). In addition, the report will describe how indicators can best be used as a tool for resource managers. The approach would include a workshop of regional experts to address the challenge of developing indicators and interpreting their utility. The North Pacific Marine Science Organization (PICES) appreciates NPRB funding for this work, which attempts to further the development of integrated ecosystem indicators for the Bering Sea. The following four objectives/activities were central for the PICES/NPRB Indicators Workshop held on June 1-3, 2006, in Seattle (Washington, U.S.A.): 1. Involve the Bering Sea and international communities in developing a set of operational objectives for the southeastern Bering Sea ecosystem; 2. Evaluate two status reports with a goal of integrating results and streamlining the presentation: a. NPFMC
Journal of Marine Science and Engineering, 2021
Following a brief review of their biology, this contribution is an attempt to provide a global ov... more Following a brief review of their biology, this contribution is an attempt to provide a global overview of the catches of mesopelagic fishes (of which 2.68 million tonnes were officially reported to the FAO) throughout the world ocean from 1950 to 2018, to serve as a baseline to a future development of these fisheries. The overview is based on a thorough scanning of the literature dealing with commercial or experimental fisheries for mesopelagics and their catches, and/or the mesopelagic bycatch of other fisheries. All commercial (industrial and artisanal) fisheries for mesopelagic fishes were included, as well as experimental fisheries of which we were aware, while catches performed only to obtain scientific samples were omitted. The processes of generating bycatch and causing discards are discussed, with emphasis on Russian fisheries. From peer-reviewed and gray literature, we lifted information on mesopelagic fisheries and assembled it into one document, which we then summarized ...
Technical Report 11, 2018
North Pacific Anadromous Fish Commission Bulletin, 2016
A comparative analysis of the trophic structure and interactions between Pacifi c salmon (Oncorhy... more A comparative analysis of the trophic structure and interactions between Pacifi c salmon (Oncorhynchus spp.) and epipelagic communities in the western Bering Sea and Pacifi c waters off the Kuril Islands was conducted using the Ecopath modeling approach. In recent decades, the nekton communities in the Bering Sea and western North Pacifi c Ocean have changed greatly. For each region, we built two models describing the trophic structure of communities (1) in a period of relatively low salmon biomass and high biomass of other nekton species (walleye pollock, Theragra chalcogramma, and/or Pacifi c sardine, Sardinops melanostictus) characteristic of the 1980s and early 1990s, and (2) in a period of high salmon biomass and greatly decreased biomass of walleye pollock and/or sardine characteristic of the 2000s. To evaluate possible changes in trophic fl ows, we also examined hypothetical scenarios in which Pacifi c salmon biomass was multiplied by 1.5 relative to their highest level in the 2000s. Despite drastic changes in the biomass of several abundant species, the overall trophic structure of epipelagic nekton communities in both the western Bering Sea and Pacifi c waters off the Kuril Islands has not changed appreciably during the last 30 years. Between the 1980s and 2000s, Pacifi c salmon biomass increased greatly in the western Bering Sea and Pacifi c waters off the Kuril Islands resulting in increased food consumption. The increase in total food consumption appears to be associated with decreases in their diet composition from groups occupying relatively high trophic levels (e.g., amphipods and squids) and a rise in prey groups occupying relatively low trophic levels (e.g., euphausiids, copepods, and pteropods). As a result of this diet shift, the estimated trophic level of Pacifi c salmon in the food web declined between the 1980s and 2000s. In the simulation with salmon biomass expanded 1.5 times relative to the 2000s estimate, the abundance of forage species was suffi cient to maintain higher salmon consumption. The ability of Pacifi c salmon to access a variety of prey species at a variety of trophic levels appears to give them the capacity to satisfy their food requirements even during periods of extremely high biomass.
Journal of Ichthyology, Oct 1, 1998
In the 1990s, an extensive body of data was gathered on the size of the Oncorhynchus gorbuscha pi... more In the 1990s, an extensive body of data was gathered on the size of the Oncorhynchus gorbuscha pink salmon populations of the Sea of Okhotsk at all the main developmental stages. A significant increase in numbers was found for juvenile pink salmon migrating into the offshore regions of the Sea of Okhotsk and the Pacific waters around the Kurils: from 250-450 million in 1990-1991 to 807-1570 million fish in 1993-1999. The overall number of migrating pink salmon in even years sharply increased in 1994 up to 215 million fish. After 1994, this estimate exceeded the number of migrating pink salmon in preceding odd years. Ocean survival of juvenile pink salmon gradually declined. This may be related to changes in the North Pacific pelagic ecosystems.
Progress in Oceanography, 2002
Journal of Fish Biology, 1996
ICES Journal of Marine Science, 2013
Hollowed, A. B., Barange, M., Beamish, R., Brander, K., Cochrane, K., Drinkwater, K., Foreman, M.... more Hollowed, A. B., Barange, M., Beamish, R., Brander, K., Cochrane, K., Drinkwater, K., Foreman, M., Hare, J., Holt, J., Ito, S-I., Kim, S., King, J., Loeng, H., MacKenzie, B., Mueter, F., Okey, T., Peck, M. A., Radchenko, V., Rice, J., Schirripa, M., Yatsu, A., and Yamanaka, Y. 2013. Projected impacts of climate change on marine fish and fisheries. – ICES Journal of Marine Science, 70: 1023–1037. This paper reviews current literature on the projected effects of climate change on marine fish and shellfish, their fisheries, and fishery-dependent communities throughout the northern hemisphere. The review addresses the following issues: (i) expected impacts on ecosystem productivity and habitat quantity and quality; (ii) impacts of changes in production and habitat on marine fish and shellfish species including effects on the community species composition, spatial distributions, interactions, and vital rates of fish and shellfish; (iii) impacts on fisheries and their associated communiti...
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Papers by Vladimir Radchenko