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Squid Overload: Berryteuthis magister in the Bering Sea

Squid Overload: Berryteuthis magister in the Bering Sea. Paige Drobny, UAF Brenda Norcross, UAF Nate Bickford, UAF. Berryteuthis magister. Magister armhook squid Hooks on their arms Maximum recorded length = 43 cm DML Weight to 2.6 kg Up to 2 year life cycle Die after spawning

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Squid Overload: Berryteuthis magister in the Bering Sea

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  1. Squid Overload: Berryteuthis magister in the Bering Sea Paige Drobny, UAF Brenda Norcross, UAF Nate Bickford, UAF

  2. Berryteuthis magister Magister armhook squid • Hooks on their arms • Maximum recorded length = 43 cm DML • Weight to 2.6 kg • Up to 2 year life cycle • Die after spawning • Sexual dimorphism • Central to the ecosystem food web • Temperature sensitive: good bioindicator! Photo credit Alaska Fisheries Science Center

  3. Distribution • Pelagic up to 1000 m • Associated with the continental shelf • Diel migrations • Ontogenetic shifts • Subspecies • B. magister nipponensis • B. magister shevtsovi Modified from Okutani et al. 1983 Kubodera 1982

  4. The role of statoliths in squid • Housed in statocyst with endolymph fluid • Controls orientation in space • Daily rings • Take up trace elements in relative proportion as the surrounding water mass

  5. Bering Sea Stabeno and Reed 1994

  6. Objectives • To establish age and growth patterns for Bering Sea B. magister and determine if there are changes in age and growth across the Bering Sea. • Use statolith chemistry to determine past movement patterns of individual B. magister. • Use statolith chemistry to combine B. magister into stock units, to develop a stock movement pattern.

  7. Western Bering Sea study on B. magister • Dispersed during summer • September and October formed large dense schools over the continental shelf • Stock stucture: Summer-hatched Fall-hatched Winter-hatched • Growth, maturation, and mortality rates varied among seasonal cohorts • Each cohort used the same areas for different portions of the life cycle Arkhipkin et.al, 1996

  8. Methods Growth • Obtain length and weight Age • Polished both sides with water on fine grit paper • Magnify 100x to count daily rings LA-ICP-MS • Core = hatch location • Edge = capture location • Transect =movement through lifetime Core line Edge line Transect line

  9. Opportunistic sampling locations • 2004 samples (numbered locations) collected from the Bering Sea Slope survey (AFSC/NMFS)- June to August • 2006 samples (red triangle) caught as bycatch in pollock trawls -September Northern Central Southern

  10. Size Distribution 2004 2006

  11. Results

  12. Max Age =188 days

  13. Age = 95-122 days Age = 84-115 days Age = 127-166 days Age = 120-177 days Age = 73-113 days Age = 114- 151 days

  14. 180 2006

  15. 180 2006

  16. Location 180/ central Location 115/ northern Location 22/ southern 2006

  17. 2004 samples

  18. 2006 samples

  19. BM1 BM10 BM182 BM219

  20. Conclusions • Squid in the Eastern Bering Sea may only live up to one year • Two cohorts are present in 2004 • At least 2 natal areas are represented by the 2 different cohorts • Squid are moving to the continental shelf from a natal area Northern Central Southern

  21. Acknowledgements • North Pacific Research Board • Dr. George Jackson, U. Tasmania • Dr. Ron O’Dor, Census of Marine Life • Mary Hunsicker, U. Washington • NMFS

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