© 2005 International Council for the Exploration of the Sea
Analyses of Bering Sea bottom-trawl surveys in Norton Sound: absence of regime shift effect on epifauna and demersal fish
a Alaska Department of Fish & Game, Commercial Fishery Division Anchorage, AK 99518, USA
b Alaska Department of Fish & Game, Commercial Fishery Division Kodiak, AK 99615, USA
c Alaska Department of Fish & Game, Commercial Fishery Division Nome, AK 99762, USA
*Correspondence to T. Hamazaki: tel: +1 907 267 2158; fax: +1 907 267 2442. e-mail: hamachan_hamazaki{at}fishgame.state.ak.us.
This study retrospectively examined evidence of ocean climate regime shift effects on epifauna and demersal fish of Norton Sound, Alaska, northeast Bering Sea, based on triennial bottom-trawl surveys from 1976 to 2002. Throughout the period, benthic fauna was dominated by sea stars (48–78%), followed by cods (5–19%), flatfish (5–15%), sculpins (1.5–7%), and crabs (2–6%). From 1976 to 2002, the cpue index of total species increased exponentially (4.5% y–1) by threefold with some declines in 1991 and 1999. The increase was also observed in sea stars (5.1% y–1), flatfish (6.1% y–1), and crabs (2.5% y–1). However, trends of cods and sculpins were mixed. Regression analysis showed the cpue index of total species to be positively correlated with survey years and bottom-water temperature. However, bottom-water temperature, when considered by itself, was not significant. Results suggest that regime shifts caused biomass increases of Norton Sound epifauna and demersal fish.
Keywords: Bering Sea, demersal fishes, epifauna, Norton Sound, regime shift
Received 29 November 2004; accepted 14 June 2005.