Некоторые аспекты российского вклада в реализацию международной программы BASIS (20022006 гг.)

• Main Authors: Шунтов, В., Темных, О., Глебов, И.
• Format: Text
• Language: unknown
• Published: Федеральное государственное унитарное предприятие «Тихоокеанский научно-исследовательский рыбохозяйственный центр» 2007
• Subjects: Anadyr; Anadyr’; Bering Sea; Pacific; Anadyr'; Sea ice; Берингов*
• Online Access: http://cyberleninka.ru/article/n/nekotorye-aspekty-rossiyskogo-vklada-v-realizatsiyu-mezhdunarodnoy-programmy-basis-20022006-gg; http://cyberleninka.ru/article_covers/4001473.png

Приводятся некоторые результаты выполнения Россией международной программы по изучению лососей в беринговоморско-алеутском регионе. Несмотря на значительное расширение объема информации по морской экологии лососей, полученной в 20022006 гг., не по всем вопросам программы BASIS был достигнут значительный прогресс, в первую очередь в связи с некоторыми недостатками организации и выполнения исследований (отсутствие синхронности работы судов России, США и Японии, использование разных классов судов, работа иностранных судов только в светлое время суток, расхождение методик учета численности гидробионтов и т.п.). Обсуждаются результаты калибровки разных типов планктонных сетей, оттер-тралов, используемых на различных типах российских судов, а также иностранных судов, выполнявших BASIS-съемки. Приведена характеристика метео-синоптических и океанологических условий в Беринговом море для периода 20022006 гг. Отмечены особенности состава планктонных сообществ в западной и восточной частях Берингова моря, а также различия в питании лососей, обусловленные региональными особенностями структуры планктонных сообществ. На большом фактическом материале подтверждена пластичность и избирательность в питании всех видов лососей. Наличие избирательности при несомненной пищевой пластичности в данном случае является важным аргументом для выводов о том, что пища в открытых водах не является жестко лимитирующим фактором функционирования лососевых стад. Сопоставление данных комплексных съемок в западной части Берингова моря в 20022006 гг. с данными более чем 20-летних экосистемных исследований ТИНРО-центра позволило проследить динамику состава пелагических сообществ в данном регионе и определить современный статус лососей в них. Несмотря на значительное снижение численности минтая в Беринговом море, он остается доминирующим по численности видом и в 2000-е гг. Суммарная биомасса лососей на порядок меньше, чем минтая. Однако в верхнем 50-метровом слое эпипелагиали к началу 2000-х гг. произошло существенное увеличение численности лососей. Если в конце 1980-х гг. на долю лососей от общей биомассы рыб приходилось 1,52,0 %, в 1990-е 43,059,0 %, то в 2000-е гг. в летние месяцы 77,584,5 %, а осенью 25,977,9 %. Высокий уровень запасов лососей в западной части моря, возможно, во многом обусловлен снижением их смертности в морской период жизни в последние годы. Main results of Russian studies in the framework of international research program BASIS are discussed. The program was conducted in 20022006 and directed on the pacific salmon research in the Bering-Aleutian region. Despite of significant enlargement of information on marine ecology acquired in the period of BASIS, not all its aspects were succeeded, primarily because of drawbacks in surveys planning and implementation (as asynchronous surveys of Russian, American and Japanese research vessels, discrepancies in vessel and gear types in use, lack of nighttime trawl stations in the US and Japanese surveys, discrepancy in species abundance estimations, and other problems). The following results are considered as the major implementation of Russia to the BASIS program: Sampling gear calibration. Different plankton nets were intercalibrated. The Juday BSD net used in Russian surveys has better sampling capability (particularly for small-size fraction) as compared to the Norpac net used in the US and Japan. Taking into account predominantly daytime sampling during the US and Japan surveys, the difference between nets may cause an underestimation of plankton abundance in the upper pelagic layer (050 m) where pacific salmons dwell by as much as tenfold. Besides, all BASIS participants, except for TINRO-center, do not take into account different catch efficiency of plankton nets (in other words, use the coefficient of catch efficiency = 1 for any plankton net) that aggravates the underestimation. The otter-trawls used by different Russian and foreign vessels were also intercalibrated. Meteorological and oceanographic observations. After the "cold" late 1990s, warming tendency was evident in the Bering Sea with weakening winter monsoon and strengthening summer monsoon after 2002. However, opposite changes in atmospheric circulation patterns started in 2004, so strengthening of winter monsoon and weakening of summer monsoons are expected for the nearest future (20072010). The Bering Sea ice cover was below normal in 20022004 but increased significantly in the winter of 20052006. Similar tendencies were observed in SST dynamics: it grew from 1999 to 20032005 and began to lower in 2006. Inflow of Pacific waters to the Bering Sea with the Central Bering Sea Current had increased in 2000s that was possible cause of significant number of pacific salmons redistribution into the western part of the Sea. Moreover, trajectories of the pacific salmon migration into the Bering Sea became longer northward. Studies on plankton communities, food base and feeding behavior of pacific salmons. Average biomass of zooplankton in the deep basin of the western Bering Sea was estimated as 600800 mg/m3 (except for 2004), in the Anadyr Bay as 8001800 mg/m3. The major its part was presented by macroplankton: 5092 % that was higher than usual (7585 %). The biomass of zooplankton in the central deep-water part of the Bering Sea was estimated as 600800 mg/m3, and in the eastern Bering Sea as 3501600 mg/m3. In opposite to the western and central Bering Sea, the eastern Bering Sea was characterized by predominance of small and medium-size plankton whereas large-size fraction didn't exceed 1045 % of total zooplankton biomass. In 2006 only the share of large-size fraction here 6065 %. Pacific salmons prefer the feeding of euphausiids and hyperiids, sometimes pteropods. The highest concentrations of these species were observed in the Russian EEZ of the Bering Sea. Probably this is one of reasons for the salmons migration into this area during summer-autumn forage period. Some geographic differences in feeding behavior of salmons were revealed, which were obviously conditioned by features of plankton communities structure in the western and eastern parts of Bering Sea. All pacific salmons species displayed both plasticity and selectivity of feeding behavior. This is an argument for the viewpoint that food availability is not important limiting factor for pacific salmons in high seas. The pacific salmons consumed 1269 % of overall food consumption of forage species by nekton in the upper pelagic layer of the western Bering Sea. This volume is significant but not very high to consider the food base of Bering Sea as the factor that limits the salmons abundance. Nekton research. New data of complex trawl surveys in the western Bering Sea obtained in 20022006 added to the results of long-term (two decades) ecosystem observations conducted in this region by TINRO-center, allow to trace dynamics of pelagic communities composition and to determine the changeable status of pacific salmon in these communities. Despite of significant decrease of walleye pollock abundance, this species still dominated in the Bering Sea. Total biomass of pacific salmons was tenfold lower than that of walleye pollock. However, significant increase of pacific salmons abundance was observed in the upper 20 m layer in early 2000s. The share of pacific salmons biomass was 1.52.0 % of total fish species biomass in late 1980s, 43.059.0 % in 1990s, and 77.584.5 % in early 2000s (in summer). In the fall season of 2000s it was 25.977.9 %. High pacific salmon abundance in the western Bering Sea is presumably attributed to their lowered marine mortality.