Population dynamics of the invasive lithodid crab, Paralithodes camtschaticus, in a typical bay of the Barents Sea

We investigated population dynamics of the introduced red king crab, Paralithodes camtschaticus (Tilesius, 1815), in Dalnezelenetskaya Bay, a typical coastal site of the Eastern Murman (Barents Sea) in summer over an 8-year period. In this bay, as in other coastal sites, juvenile crabs were most abundant. Among large crabs, the sex ratio was highly biased to females suggesting the important role of shallow water areas in reproduction of the red king crab. In 2002-2004, the carapace length (CL) frequency distribution of small crabs tended to be bimodal (30 and 60 mm). In 2005-2007 and 2009, crabs with a modal CL of 20 and 40 mm dominated. For small crabs, weight-length relationships were similar in males and females, while for large crabs the relationships differed significantly between sexes. Large males had a greater carapace width (CW) and merus length (ML), and higher CW/CL and ML/CL ratios, than large females due to sexual dimorphism. In 2002-2007, the total number of red king crabs was estimated to be 4100-7400 individuals; in 2008, we observed a marked decline to 350 individuals; in 2009, the total stock increased again to 3760 individuals. The observed patterns are in accordance with the stock dynamics reported for other coastal areas and could be associated with high levels of illegal fishing including recreational diving.