1. Analyses of Bering Sea bottom- trawl surveys in Norton Sound: Absence of regime shift effect on epifauna and demersal fish Toshihide “Hamachan” Hamazaki Alaska Department of Fish & Game Division of Commercial Fisheries Anchorage Alaska ICES Journal of Marine Science 62: 1597-1602 (2005)

2. Effects of Regime Shifts are Real! Anderson 2000 Effects of Regime Shifts on the Bering Sea Ecosystem is well documented Several mechanisms have been proposed -Ocean current pattern -Sea ice distribution -Location of upwelling -Bottom up vs. Top down

3. However, most studies are limited to the Gulf of Alaska and Southeastern Bering Sea. Hare & Mantua 2000

4. Bering Sea Ecosystem Consists of Several Distinct Water Masses / Ecosystems Are the effects of Regime Shift the same among various ecosystems?

5. Norton Sound Ecosystem Inshore water system isolated from major ocean currents Inshore water system isolated from major ocean currents Shallow water depth (< 30 m) Shallow water depth (< 30 m) Ice Cover for 6 months Ice Cover for 6 months Influx of freshwater and nutrients from rivers Influx of freshwater and nutrients from rivers Dominated by Invertebrates Dominated by Invertebrates

6. Norton Sound Trawl Survey One of a few long-term survey data available in the north Bering Sea One of a few long-term survey data available in the north Bering Sea Started 1976 for development of red king crab fishery. (There has been no major fisheries in Norton Sound) Started 1976 for development of red king crab fishery. (There has been no major fisheries in Norton Sound) Triennially by NMFS (76-91) and by ADF&G (96-02) Triennially by NMFS (76-91) and by ADF&G (96-02) Identify & weigh all vertebrates and invertebrates captured. Identify & weigh all vertebrates and invertebrates captured.

7. Total Biomass Change

8. Increasing Trends Total CPUE Flat-fishesCrabs Sea-Stars

9. Trends among 48 taxonomic groups

10. Taxonomic Composition

11. Bottom Water Temperature

12. Other Species Nome Air Temperature Coho Catch Chinook CatchChum Catch Sockeye Catch

13. Conclusion Norton Sound benthic biomass increased by 3 folds from 1976 to 2002 across major taxoninc groups. Norton Sound benthic biomass increased by 3 folds from 1976 to 2002 across major taxoninc groups. Benthic composition did not significantly change from 1976 to 2002. Benthic composition did not significantly change from 1976 to 2002. No Apparent Regime Shifts Effects were detected. No Apparent Regime Shifts Effects were detected. –Increase of overall biomass can be attributed to temperature increase since 1976 (Regime shifts effects?)

14. Discussion Norton Sound ecosystem characteristics differ from SE Bering Sea, which resulted in the lack of Regime Shift effects Norton Sound ecosystem characteristics differ from SE Bering Sea, which resulted in the lack of Regime Shift effects Effects and influential mechanisms of Regime Shift would differ among regional ecosystems Effects and influential mechanisms of Regime Shift would differ among regional ecosystems Need to study/monitor various parts of Bering Sea Need to study/monitor various parts of Bering Sea

15. Further Study Directions 2006 Trawl Survey 2006 Trawl Survey (Pending: No bidders 2005 ) (Pending: No bidders 2005 ) –This Survey may show a significant faunal change. –Virtual disappearance of sea star from winter king crab survey since 2003 Spatial-Temporal Analyses Spatial-Temporal Analyses (NPRB funding proposal) (NPRB funding proposal) –Identify areas of high biomass, species richness and diversity –Examine changes in spatial distribution –Correlate spatial distribution of major species with environmental variables –Construct potential habitat prediction model

16. 1976 Red King Crab Distribution

17. 1979 Red King Crab Distribution

18. 1982 Red King Crab Distribution

19. 1985 Red King Crab Distribution

20. 1988 Red King Crab Distribution

21. 1991 Red King Crab Distribution

22. 1996 Red King Crab Distribution

23. 1999 Red King Crab Distribution

24. 2002 Red King Crab Distribution What Caused Those Changes?

25. Further Study Directions 2006 Trawl Survey 2006 Trawl Survey (Pending: No bidders 2005 ) (Pending: No bidders 2005 ) –This Survey may show a significant faunal change. –Virtual disappearance of sea star from winter king crab survey since 2003 Spatial-Temporal Analyses Spatial-Temporal Analyses (NPRB funding proposal) (NPRB funding proposal) –Identify areas of high biomass, species richness and diversity –Examine changes in spatial distribution –Correlate spatial distribution of major species with environmental variables –Construct potential habitat prediction model

26. Q & A