SSL_Climate_Synthesis_FO_submitted
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SSL_Climate_Synthesis_FO_submitted
Bottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submitted D. G. Maschner3,Michael A. Alexander, Steven J. Bograd5, John A. Calder6, Antonietta Capotondr,Kenneth 0. Coyle’, Emanuele Di Lorenzo8, Bruce p. Finney', Lowell Fritz9,Edward J. Gregr1, Chester E. Grosch10, Steven R. Hare11, George L. Hunt12,Jaime Jahncke", Nancy B. Kachel13, Hey-Jin Kim2, Carol La SSL_Climate_Synthesis_FO_submitteddd12, Nathan J. Mantua14,Caren Marzban13, Wieslaw Mastowski16, R. Mendelssohn5, Douglas J. Neilson2, Stephen R. Okkonen*, James E. Overland13, KatheriSSL_Climate_Synthesis_FO_submitted
ne L. Reedy-Maschner3,Thomas c. Royer10, F. B. Schwing5, Julian X. L. Wang1' and Arliss J. Winship1‘University of British Columbia, Vancouver, BC, CanBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submittedEnvironmental Laboratory, Pacific Grove, CA4N0AA Oceanic and Atmospheric Research, Silver Springs. MD’University of Alaska. Fairbanks. AK•‘Georgia Institute of Technology, Atlanta, GA^National Marine Fisheries Service, Seattle, WA10Old Dominion University, Norfolk, VA“International Pacific Halibut C SSL_Climate_Synthesis_FO_submittedommission. Seattle. WA“University of California, Irvine, CA“Pacific Marine Environmental Laboratory. Seattle, WA“University of Washington, Seattle. WASSL_Climate_Synthesis_FO_submitted
“University of Oklahoma, Norman, OK14 Nava I Postgraduate School. Monterey. CA• NOAA Air Resources Lab, Silver Spring, MD•Correspondence, e-mail: ajmiBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submitted Gulf of Alaska could be a consequence of physical oceanographic changes associated with the 1976-77 climate regime shift. Changes in ocean climate are hypothesized to have affected the quantity, quality and accessibility of prey, which in turn may have affected the rates of birth and death of sea l SSL_Climate_Synthesis_FO_submittedions. Recent studies of the spatial and temporal variations in the ocean climate system of the North Pacific are consistent with this hypothesis. OceaSSL_Climate_Synthesis_FO_submitted
n climate changes appear to have created adaptive opportunities for various species that are preyed upon by Steller sea lions at mid-trophic levels. CBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submittedate 1970’s) and the spatial aspect of the decline (western, but not eastern, populations decreased). The basin-wide climate variations of the North Pacific also correspond with regionally sensitive biogeographic structures along the Aleutian Islands and Gulf of Alaska, which include a transition poi SSL_Climate_Synthesis_FO_submittednt from coastal to open-ocean conditions at Samalga Pass westward along the Aleutian Islands. Paleontological records spanning 4000 years further indiSSL_Climate_Synthesis_FO_submitted
cate that sea Hon populations have experienced major shifts in abundance in the past. Shifts in ocean climate are the most parsimonious underlying expBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submittedopulations (Eumetopias jubatus) declined by over 80% between the late 1970s and early 1990s in the western Gulf of Alaska and in the Aleutian Islands (Fig. 1). Concurrent declines also occurred farther west in the Russian coastal waters. However, population trends wore reversed along the coasts of S SSL_Climate_Synthesis_FO_submittedoutheast Alaska. British Columbia, Washington and Oregon where sea lions increased through the 1980s and 1990s (Loughlin, 1998; Trites and Larkin, 199SSL_Climate_Synthesis_FO_submitted
0). The cause orcauses of these population changes have not been resolved and have been the subject OÍ considerable debate and research (DeMaster and Bottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submitteds focused on trying to identify a single cause for the changes, rather than recognizing that many of the proposed theories are inter-related. As shown in Fig. 2, the leading hypotheses of epidemic diseases, predation by killer whales, ocean climate change (regime shifts), and nutritional shifts in t SSL_Climate_Synthesis_FO_submittedypes of prey available to sea lions (the junk food hypothesis) may all be linked through bottom-up processes. Conceptually, changes in water temperatuSSL_Climate_Synthesis_FO_submitted
res, ocean currents and other oceanographic variables can influence the survival and distribution of assemblages of species that are consumed by predaBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submittedsufficient energy will typically be fat and large, and experience reduced levels of oxidative stress al a cellular level. In contrast, inadequate nutrition can increase oxidative stress (and susceptibility' to disease), reduce body fat (and pregnancy rates), and increase rates of predation (as a fun SSL_Climate_Synthesis_FO_submittedction of reduced body size or increased vulnerability while spending longer times searching for prey). Such changes to the health of individuals ultimSSL_Climate_Synthesis_FO_submitted
ately translate into changes in numbers at a population level through decreased birth rates and increased death rates.A major change in both the physiBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. Herbert SSL_Climate_Synthesis_FO_submitted primary productivity, fisheries, and other variables (e.g. Beamish, 1993: Benson and Trites, 2002; Hare and Mantua. 2000; Mantua et al., 1997; Miller et al..3 SSL_Climate_Synthesis_FO_submittedBottom-Up Forcing and the Decline of Steller Sea Lions in Alaska: Assessing the Ocean climate HypothesisAndrew w. Trites1. Arthur J. Miller’. HerbertGọi ngay
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