The Snow Crab, Chionoecetes opilio (Decapoda, Majoidea, Oregoniidae) in the Barents Sea

Abstract

The snow crab, Chionoecetes opilio (Fabricius, 1788), is recorded from the North Pacific, Arctic and Northwest Atlantic. In 1996 however, Russian fishing vessels captured five snow crabs in the Barents Sea and since then, fishing vessels operating in the area have occasionally reported this spider crab in the by-catch. Annual bottom-trawl surveys conducted jointly by Russia and Norway since 2004 have confirmed the presence of C. opilio in the northern region of the Barents Sea. Furthermore, in 2008 an increase in abundance and distribution range was found with a significant number of crabs being recorded in the central region of the Barents Sea, mainly between 180 and 350 m deep, in depths and temperatures similar to the species natural habitat in the Northwest Atlantic and North Pacific. The carapace width (CW) of the captured snow crabs typically range from 14 to 130 mm. About 40% of the crabs were juveniles (CW smaller than 50 mm), providing evidence for successful recruitment. These small-sized crabs were exclusively found on Goose Bank, identifying it as the main recruiting area. Ovigerous crabs have been collected since 2004, and the smallest female with extruded eggs measured 65 mm CW. Females larger than 80 mm CW were all egg carrying. Minimum size at maturity in male snow crab, based on presence of spermatophores, was estimated to be 43 mm CW. All males larger than 45 mm CW were mature and can potentially engage in mating. Their diet consisted of benthic organisms such as crustaceans (mainly decapods), polychaetes, molluscs, echinoderms and fish. The Barents Sea population of the snow crab seems to possess similar biological characteristic as those occurring in its natural distribution areas. Chionoecetes opilio was unintentionally introduced to the Barents Sea and as yet the processes that might limit recruitment and distribution are unknown as are its origins. Genetic methods based on new microsatellite markers have been developed and applied to several Northwestern Atlantic crab populations. It is hoped that these markers will allow identification of the origins of the snow crab population in the Barents Sea.