scholarly journals The Aleutian Low and Winter Climatic Conditions in the Bering Sea. Part I: Classification*

2005 ◽  
Vol 18 (1) ◽  
pp. 160-177 ◽  
Author(s):  
S. N. Rodionov ◽  
J. E. Overland ◽  
N. A. Bond

Abstract The Aleutian low is examined as a primary determinant of surface air temperature (SAT) variability in the Bering Sea during the winter [December–January–February–March (DJFM)] months. The Classification and Regression Tree (CART) method is used to classify five types of atmospheric circulation for anomalously warm months (W1–W5) and cold months (C1–C5). For the Bering Sea, changes in the position of the Aleutian low are shown to be more important than changes in its central pressure. The first two types, W1 and C1, account for 51% of the “warm” and 37% of the “cold” months. The W1-type pattern is characterized by the anomalously deep Aleutian low shifted west and north of its mean position. In this situation, an increased cyclonic activity occurs in the western Bering Sea. The C1-type pattern represents a split Aleutian low with one center in the northwestern Pacific and the other in the Gulf of Alaska. The relative frequency of the W1 to C1 types of atmospheric circulation varies on decadal time scales, which helps to explain the predominance of fluctuations on these time scales in the weather of the Bering Sea. Previous work has noted the prominence of multidecadal variability in the North Pacific. The present study finds multidecadal variations in frequencies of the W3 and C3 patterns, both of which are characterized by increased cyclonic activity south of 51°N. In general, the CART method is found to be a suitable means for characterizing the wintertime atmospheric circulation of the North Pacific in terms of its impact on the Bering Sea. The results show that similar pressure anomaly patterns for the North Pacific as a whole can actually result in different conditions for the Bering Sea, and that similar weather conditions in the Bering Sea can arise from decidedly different large-scale pressure patterns.

2009 ◽  
Vol 75 (2) ◽  
pp. 359-367 ◽  
Author(s):  
Shogo Moriya ◽  
Shunpei Sato ◽  
Moongeun Yoon ◽  
Tomonori Azumaya ◽  
Shigehiko Urawa ◽  
...  

1973 ◽  
Vol 30 (12) ◽  
pp. 2373-2385 ◽  
Author(s):  
A. T. Pruter

Fisheries for bottomfish in the Bering Sea are largely a post-second world war development, with landings having increased from 13,000 metric tons in 1954 to an estimated 2 million metric tons in 1971. Most of the harvest is off Alaska in the southeastern sector of the Bering Sea, where conditions are most favorable for development of resources and fisheries. In 1970 and 1971, Japan accounted for approximately 84% and the USSR 15% of the combined harvest by all nations. South Korea, United States, and Canada took the remaining 1% of the harvest. Initial target of the fisheries of Japan and USSR was yellowfin sole. Yields of yellowfin sole were not sustained and Japan shifted attention to Alaska pollock. Production of Alaska pollock in 1970 from the North Pacific (about half is from the Bering Sea) was tied with Atlantic cod for second place in worldwide landings of a single species.Analysis of condition of resources is handicapped by unavailability of adequate statistics for earlier years of the fishery. Even for those participants who provided detailed statistics, information is usually lacking on quantities offish discarded, and changes in fishing gear and fishing tactics that need to be corrected for in assessing the condition of stocks. There is no institutional mechanism for Bering Sea or the North Pacific that makes it mandatory for all nations to provide common and comprehensive statistics on their fisheries and to undertake joint management.Consideration of available data suggests that the pulse nature of the Bering Sea fisheries resulted in the depletion of several important resources. Yellowfin sole were overfished during the early period of the fishery. Although the picture is far from clear for other species, the Pacific Ocean perch, blackcod, and shrimp resources also appear to have been overfished at least on certain important grounds within the Bering Sea. The chronology of Japan’s fishery for herring suggests the initial exploitation of the stock in the western Bering Sea off Asia may have been intense enough to deplete that resource. Although there is yet no indication of depletion of Alaska pollock, the great increase in harvest of that species, coupled with reliance on a few year classes to support the fishery, should serve as a warning against further uncontrolled increases in fishing.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Sabrina Garcia ◽  
Cindy A. Tribuzio ◽  
Andrew C. Seitz ◽  
Michael B. Courtney ◽  
Julie K. Nielsen ◽  
...  

Abstract Background The salmon shark (Lamna ditropis) is a widely distributed apex predator in the North Pacific Ocean. Many salmon sharks from the eastern North Pacific, specifically Prince William Sound, Alaska, have been satellite tagged and tracked, but due to the sexual segregation present in salmon sharks, most of these tagged sharks were female. Consequently, little information exists regarding the migration patterns of male salmon sharks. To better understand the migration and distribution of this species, information on the male component of the population as well as from sharks outside of Prince William Sound, Alaska, is needed. In this study, we deployed satellite transmitters on two mature male salmon sharks caught in the Bering Sea. Results The two mature male salmon sharks tagged in the Bering Sea exhibited distinct migration patterns. The first male, tagged in August 2017, traveled to southern California where it remained from January to April after which it traveled north along the United States’ coast and returned to the Bering Sea in August 2018. The second male, tagged in September 2019, remained in the North Pacific between 38° N and 50° N before returning to the Bering Sea in July of year one and as of its last known location in year two. The straight-line distance traveled by the 2017 and 2019 sharks during their 12 and 22 months at liberty was 18,775 km and 27,100 km, respectively. Conclusions Before this study, our understanding of salmon shark migration was limited to female salmon sharks satellite tagged in the eastern North Pacific. The 2017 male salmon shark undertook a similar, but longer, north–south migration as tagged female sharks whereas the 2019 shark showed little overlap with previously tagged females. The different migration patterns between the two male sharks suggest distinct areas exist for foraging across the North Pacific. The return of both sharks to the Bering Sea suggests some fidelity to the region. Continued tagging efforts are necessary to understand the population structure of salmon sharks in the North Pacific. This tagging study highlights the importance of opportunistic efforts for obtaining information on species and sex with limited distribution data.


2019 ◽  
Vol 198 ◽  
pp. 239-261
Author(s):  
A. F. Volkov

Structure of the databases «Zooplankton…» and «Nekton trophology» is described and some techniques are proposed for nekton studies using these bases in conjunction with the database «Marine Biology». All three databases are regularly updated. The bases «Zooplankton…» and «Nekton trophology» contain raw data on plankton and feeding of nekton collected in the North Pacific and the Okhotsk, Bering and Chukchi Seas in 1984–2018. The «Nekton trofology» database contains information for 97 species of nekton, mostly for mass species (72–78 % of samples belong to 5 most numerous species), and 156 species of prey, including 27 species of Copepoda, 7 species of Euphausiacea, 9 species of Amphipoda, 14 species of Decapoda, 6 species of Coelenterata, 15 species of Cephalopoda, and 60 species of Pisces, other groups of prey are represented by 1–2 species. The data are spatially sorted by biostatistical areas and their sub-areas, in total 64 sub-areas in the Okhotsk Sea, 32 areas in the Bering Sea, 30 areas in the North Pacific, and 5 areas in the Chukchi Sea. Mean depth is determined for each sub-area. Method of spatial distribution mapping is demonstrated with using the sub-areas as integral stations or the 1-degree grid for Surfer software. Technique of regional inventory is explained with summarizing and averaging the data and calculation of various indicators as plankton–nekton ratio, etc. The 1-degree trapeziums are numbered for easier usage. Some useful examples are presented with the author’s comments (showing his personal opinion).


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