Population assessment of snow crab, Chionoecetes opilio, in the Chukchi and Beaufort Seas including oil and gas lease area

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Background information

Snow crab Chionoecetes opilio O. Fabricius support major fisheries in the US eastern Bering Sea. Since the onset of this fishery in the US in the 1970s, catches increased until the early 1990s but were much reduced in the early 2000s. The male-only fishery is regulated by a quota, by season and by a minimum legal size, preventing the harvest of the much smaller females. Snow crabs are not fished in the Chukchi and Beaufort Seas, but occur all across the Chukchi shelf and at least in the western Beaufort Sea. They have not been found at the adjacent lower slopes (1000 m and deeper) or in the Canada Basin. In recent years the geographic range of distribution of C. opilio in the Bering Sea has contracted northward. Our own work suggests distribution shifts of C. opilio also within the Chukchi Sea.

Snow crab stock size and structure is strongly shaped by life cycle characteristics. Snow crabs are long-lived (~15 years in the case of large males) and undergo a series of molts during their first years of life before final size is reached at terminal molt. In the Bering Sea, reproductive maturity is reached at about 5-8 years of age at an average carapace width (CW) of 8.4 cm for males and 5.1 cm for females (www.nmfs.noaa.gov/fishwatch). Female snow crabs mature at smaller size in colder waters at higher latitudes and at larger size in warmer temperatures at lower latitudes (Jewett 1981). Snow crabs found in the Chukchi Sea are generally smaller than in the Eastern Bering Sea (mostly smaller than 5 cm CW), but crabs as large as 10 cm CW were recently found on the Beaufort Sea slope.

There is an urgent need for stock assessments of key Arctic marine species in light of increased interest in oil and gas development and climate change-related environmental shifts in the Chukchi and Beaufort Seas. The recent shifts in distribution of invertebrates and fishes in the sub-Arctic and Arctic are not only potential indicators of climate warming, but have also spurred interest in evaluating potential future Arctic fisheries and assessing risk associated with oil and gas activities. This requires sound background information on stock size and structure and reproductive condition.

Useful references

Alvsvåg J, Agnalt AL, Jørstad KE (2009) Evidence for a permanent establishment of the snow crab (Chionoecetes opilio) in the Barents Sea. Biol Invasions 11:587-595
Bluhm BA, Iken K, Mincks SL, Sirenko BI, Holladay BA (2009) Community structure of epibenthic megafauna in the Chukchi Sea. Aquat Biol 7:269-293
Ernst B, Orensanz JM, Armstrong DA (2005) Spatial dynamics of females snow crab (Chionoecetes opilio) in the eastern Bering Sea. Can J Fish Aquat Sci 62:250-268
Feder HM, Jewett SC, Blanchard A (2005) Southeastern Chukchi Sea (Alaska) epibenthos. Polar Biol 28:402-421
Frost KJ, Lowry LF (1983) Demersal fishes and invertebrates trawled in the northeastern Chukchi and western Beaufort Seas, 1976-77. NOAA Technical Report NMFS SSRF-764
Hardy SM, Lindgren M, Konakanchi H, Huettmann F (2011) Predicting the distribution and ecological niche of unexploited snow crab (Chionoecetes opilio) populations in Alaskan waters: A first open-access ensemble model. Integr Comp Biol 51: 608-622.
Iken K, Bluhm BA, Dunton K (2010) Benthic food web structure serves as indicator of water mass properties in the southern Chukchi Sea. Deep-Sea Res II 57:71-85
Jadamec LS, Donaldson WE, Cullenberg P (1999) Biological field techniques for Chionoecetes crabs. Alaska Sea Grant College Program AK-SG-99-02
Jewett SC (1981) Variations in some reproductive aspects of female snow crabs Chionoecetes opilio. J Shellfish Res 1:95-99
Kruse GH, Eckert GL, Foy RJ, Lipcius RN, Sainte-Marine B, Stram DL, Woodby D (2010) Biology and management of exploited crab populations under climate change. Alaska Sea Grant College Program, University of Alaska Fairbanks
Logerwell L, Rand K (2010) Beaufort Sea marine fish monitoring 2008: pilot survey and test of hypotheses. OCS Study MMS 2008-062, Final report
Orensanz JM, Ernst B, Armstrong DA (2007) Variation of female size and stage at maturity in snow crab (Chionoecetes opilio) (Brachyura: Majidae) from the eastern Bering Sea. J Crust Biol 27:576-591
Orensanz J, Ernst B, Armstrong DA, Stabeno P, Livingston P (2004) Contraction of the geographic range of distribution of snow crab (Chionoecetes opilio) in the Eastern Bering Sea: An environmental ratchet? CalCOFI Report, p 65-79
Paul JM, Paul AJ, Barber WE (1997) Reproductive biology and distribution of the snow crab from the northeastern Chukchi Sea. Am Fish Soc Sym 19: 287-294
Rand KM, Logerwell EA (2010) The first demersal trawl survey of benthic fish and invertebrates in the Beaufort Sea since the late 1970s. Polar Biol 34:475-488
Sainte-Marie B, Sevigny JM, Smith BD, Lovrich GA (1996) Recruitment variability in snow crab (Chionoecetes opilio): patterns, possible causes, and implications for fishery management. In: High latitude crabs: Biology, management and economics. Alaska Sea Grant College Program Report 96-02, University of Alaska Fairbanks, pp 451-478
Sainte-Marie B, Sevigny JM, Carpentier M (2002) Interannual variability of sperm reserves and fecundity of primiparous females of snow crab (Chionoecetes opilio) in relation to sex ratio. Can J Fish Aquat Sci 59:1932-1940
Zheng J, Kruse GH, Ackley DR (2001) Spatial distribution and recruitment patterns of snow crabs in the eastern Bering Sea. In: Spatial processes and management of marine populations. Alaska Sea Grant College Program AK-SG-01-02, University of Alaska, pp 233-255

Links to snow crab information
Snow crab stock assessment through annual Eastern Bering Sea trawl surveys: http://www.afsc.noaa.gov/Kodiak/shellfish/crabEBS/crabsurvey.htm
Snow crab trawl survey database southern Gulf of St. Lawrence Canada: http://gcmd.nasa.gov/records/GCMD_OBIS.DFO_Gulf_SnowCrabSurveys.html
Biology and ecology of Atlantic snow crab: http://www.dfo-mpo.gc.ca/Science/publications/uww-msm/articles/snowcrab-crabedesneiges-eng.html
Ecology, fisheries and management of Bering Sea snow crab: http://www.nmfs.noaa.gov/fishwatch/species/snow_crab.htm
Snow crab in west Greenland: http://www.marine.ie/NR/rdonlyres/27790180-34A6-4B17-B9FA-91CEA5783EB3/0/Snowcrab07.pdf
Relatively new snow crab stock in the Barents Sea: http://www.barentsportal.com/barentsportal09/index.php?option=com_content&view=article&id=368&Itemid=268&lang=en

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page modified February 14, 2013.