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Greg Albrecht Dr. Sarah M. Hardy Dr. Kris Hundertmark

Defining genetic population structure of snow crab ( Chionoecetes opilio ) in the Bering, Chukchi and Beaufort Seas . Greg Albrecht Dr. Sarah M. Hardy Dr. Kris Hundertmark. Outline. Species information Study area Factors influencing current populations Purpose of study Methods Progress.

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Greg Albrecht Dr. Sarah M. Hardy Dr. Kris Hundertmark

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  1. Defining genetic population structure of snow crab (Chionoecetes opilio) in the Bering, Chukchi and Beaufort Seas Greg Albrecht Dr. Sarah M. Hardy Dr. Kris Hundertmark

  2. Outline Species information Study area Factors influencing current populations Purpose of study Methods Progress

  3. Distribution(Approximated) Koryaks.net

  4. Life History • Planktonic zoea – (hatch in winter – spring, 2 stages, 3-5 months) • Settle as megalopae • Molt through 7-9 instars • Males: 5-10 years • Females: 3-7 years • Terminal molt to maturity • Up to 7 years post terminal molt • Males: 11-17 years • Females: 10-13 years uwlax.edu Kruse et al. 2007

  5. Shell condition Index (Not full representation) Abdominal flap is proportionally larger in mature females 1 2 3 4

  6. Mating • Mating in late winter • Females can store sperm in spermathaeca for later use • Males can fertilize several females • Young are brooded 12-15 months then released into water column Female Male

  7. Larval Dispersal • Predominantly northward flow • Bering Strait to Pt. Barrow ~6 months Weingartner et al. 2005

  8. Bering Sea Mean circulation of upper 40 m • Local recruitment • Eddies • Weak currents in central • Southward migration? Stabeno 2001

  9. Migration • Adult females move from coastal domain towards outer domain (SW) • Male migration not studied as well Ernst et al. 2005 Koryaks.net

  10. The forces at work • Commercial fishing pressure • Concentrating on southern extent of population • Climate change • Temperatures, ice extent, ocean currents, wind & mixing • Predator prey • Pacific Cod (Gadus macrocephalus) and other bottom fish • Resource exploration

  11. Commercial Harvest • One of the largest crab fisheries in the world • 2008~ 90 million dollars • 1992~ 192 million • Replaced dwindling Tanner (C. bairdi) stocks in 1980s rcrawford79.wordpress.com Kruse et al. 2007

  12. Climate change • Ice extent determines cold pool (<2 C) • Cold pool trapped by stratified warm water • Crabs follow cold pool • Can crabs re-colonize south after a warm year? • Cod predation may be too intense Orensanz et al . 2004

  13. Resource Exploration Areas Alaska Annual Studies Plan. U.S. Dept. of Interior 2009

  14. Purpose of Study • Gain a better understanding of genetic connectivity • Identify genetically distinct subpopulations if they exist • Gain a better understanding of larval dispersal distances

  15. Sampling Sampled Commercial fishing Planned sampling Resource development

  16. Methods • Based on Puebla et al. 2008 (North Atlantic) • Extract DNA samples from tissue in ~ 1000 adult female C. opilio samples collected from throughout their range • Amplify DNA using PCR at 8 microsatellite locations • Genotype each individual • Use statistical programs to analyze results and look for distinct populations • Match larval crabs with upstream populations

  17. Why Microsatellites? • Definition: Molecular markers consisting of repeat nucleotide units at various locations within nuclear DNA • Previously established for this species by Puebla et al. 2003 • Shown to be informative in this species • Highly polymorphic, yet not under selection pressures • Deviation from Hardy-Weinberg equilibrium can be used to detect isolation of a group of individuals

  18. Statistics • A suite of computer programs will be used to identify genetically isolated populations • F-statistics • Compare pre-established groups in a framework similar to ANOVA • Bayesian methods • Assemble populations based on similarity of genetic signatures

  19. The big picture Crab DNA PCR (Copying of target DNA) 8 primers (Identify region for copying) Electrophoresis Taq polymerase (Copies DNA) Scoring of each individual’s electropherogram Statistical analysis of genetic signatures

  20. Microsatellite locations are represented by different colors

  21. So how does this work?

  22. Population “A” Population “B” Electropherogram Allele “A” Allele “B” 110 100 Heterozygote Mating 100 Electrophoresis PCR Primer region 110

  23. Population “A” Population “A” Electropherogram Allele “A” Allele “A” 100 100 Homozygote Mating 100 Electrophoresis PCR Primer region PCR conditions must be optimized for good amplification 100

  24. Chukchi Chukchi

  25. Chukchi Beaufort

  26. Progress to date • Extracted ~150 samples • Tested DNA quality and found donated Bering samples to be low • Multiplexed all 8 primers • Trial and error of PCR conditions (various annealing temperatures and times, Taq polymerases) • Initial genotyping of individuals

  27. Timeline • Winter 2009/10 – begin genotyping (currently underway) • May 2010 – have completed genotyping and preliminary statistical analysis for 60 individuals • July 2010 – Collect samples from Bering Sea on F&G trawl survey cruise • February 2011 – have completed genotyping and analysis for entire sample collection • September 2011 – have written and defended thesis

  28. Literature Cited • Ernst, B., Orensanz J. M. & Armstrong, D. A. 2005. Spatial dynamics of female snow crab (Chionoecetes opilio) in the eastern Bering Sea. Canadian Journal of Fisheries and Aquatic Science 62:250-268. • Kruse, G.H. , Tyler, A.V, Sainte-Marie, B., Pengilly, D. 2007. A workshop on mechanisms affecting year-class strength formation in snow crabs Chionoecetes opilio in the Eastern Bering Sea • Orensanz, J., B. Ernst, D. A. Armstrong, P. Stabeno, and P. Livingston. 2004. Contraction of the geographic range of distribution of snow crab (Chionoecetes opilio) in the Eastern Bering Sea: An environmental ratchet? Pages 65-79, CalCOFI Report. • Puebla, O., Parent, E. & Sevigny, J.-M. 2003. New microsatellite markers for the snow crab Chionoecetes opilio (Brachyura: Majidae). Molecular Ecology Notes. 3:644-646. • Puebla, O., Sevigny, J.-M., Sainte-Marie, B., Brethes, J.-C., Burmeister, A., Dawe, E. G. and Moriyasu. M. 2008. Population genetic structure of the snow crab (Chionoecetes opilio) at the Northwest Atlantic scale. Canadian Journal of Fisheries and Aquatic Sciences 65:425-436. • Stabeno, P.J., Kachel, N.B., Salo, S.A. & Schumacher, J.D. 2001. On the temporal variability of the physical environment over the south-eastern Bering Sea. Fisheries Oceanography 10(1) 81-98. • Weingartner, T., Aagaard, K., Woodgate, R., Danielson, S., Yasunori, S. & Cavalieri, D. 2005. Circulation on the north central Chukchi Sea shelf. Deep-Sea Research II 52: 3150-3174.

  29. Questions and Comments?

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