Parasitism of the golden king crab, Lithodes aequispinus, by two species of snailfish, genus Careproctus

Somerton, D.A.; Donaldson, W.

Fishery Bulletin (Washington D C) 96(4): 871-884

1998


ISSN/ISBN: 0090-0656
Accession: 018045084

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Abstract
Along the continental slope of the eastern Bering Sea, two species of Careproctus snailfishes deposit eggs within the branchial chambers of the commercially important golden king crab (Lithodes aequispinus). The larger of the two species is the pink snailfish (C. furcellus); the smaller species is an undescribed species referred to as the red snailfish. According to 1982 trawl survey data, incidence of snailfish eggs and larvae within crab branchial chambers increases with carapace length (CL) and is greater for male than female crabs. A logistic model fitted to the incidence data predicts that a 140-mm-CL male will have an incidence of 0.52, approximately 1.9 times greater than the incidence for a 100-mm male. Incidence for a 100-mm-CL male is approximately 1.9 times greater than that for a female of equal size. On the basis of developmental stages of embryos carried by female golden king crab and the developmental stages of snailfish embryos within a female's branchial chambers, snailfish appear to deposit eggs preferentially in crabs that are early in their molt cycle. The presence of the egg masses results in gill compression, localized necrosis of gill tissue and, in extreme cases, total loss of gill tissue on one side of the body. For crabs of commercial size, the presence of eggs and larvae increases mortality within the holds of fishing vessels by 35%. The current incidence of eggs and larvae in commercial sized males, however, is so low that the effect on the commercial fishery is considered to be small.