Tuesday, July 19, 2011

Arctic Opies

I’ve mentioned invasive crabs here (Chinese mitten crabs), here (kings in Antarctica) and briefly here (green shore crabs all over), but did you know snow crabs Chionoecetes opilio are turning up where they aren’t expected too?

Shocking, right? Because who wouldn’t want snow crabs around? Well, maybe the other critters in the Barents Sea, including the previously
introduced red king crab (Paralithodes camtschaticus). Snow crabs were first caught by Russian vessels in 1996 (5 in total) and have apparently grown in numbers since then.

"normal" distribution of snow crab Chionoecetes opilio in grey;
the blue star shows the Barents Sea

Alvsvåg et al (2009) showed, through surveys from 2004 – 2006, that opies have in fact established a population in the Barents Sea. Not only were there large males and females, but the researchers also measured little opies, indicating successful recruitment into the Barents Sea population.

quite the range: large and small male opies from the Barents Sea

In their snow crab chapter of the new book, In The Wrong Place, Agnalt et al (2011) also mentioned the abundance of juvenile snow crabs during yearly Barents Sea surveys; about 40% of the measured crabs were juvies! New recruits in the Barents Sea suggest that this snow crab population either has no competition with other benthic animals or they are out-competing their benthic neighbors for food/space. My question: what could this mean for the red kings?

Invasive opies:
Alvsvåg, J., A.-L. Agnalt, and K. E. Jørstad. 2009. Evidence for a permanent establishment of the snow crab (Chionoecetes opilio) in the Barents Sea. Biological Invasions 11: 587 – 595.

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