EPIBIONTS OF THE TANNER CRAB CHIONOECETES BAIRDI IN THE REGION OF KODIAK ISLAND, ALASKA

Abstract

ABSTRACT We examined the epibionts on 98 legal male Tanner crabs (Chionoecetes bairdi) of varying, known shell ages, which were tagged in the region of Kodiak Island, Alaska, and recovered in the commercial fishery. We found 39 species or collective taxa of organisms on C. bairdi, a conservative estimate of the number of species involved. Seven species or collective taxa occurred on the exposed outer surface of ≥50% of all crabs examined: Alcyonidium sp., Balanus spp., a tube-dwelling amphipod, Spirorbis spp., Serpula spp., a lichenoporid bryozoan, and the fungus Trichomaris invadens.At least 12 species occurred in the branchial chamber. Of these, Triticella sp., Alcyonidiumsp., and mucoid-tube polychaetes were found in ≥50% of 25 branchial cavities examined. Three species (Triticella sp.; a small, white flatworm; and Hiatella arctica) were found only in the branchial chamber. Our data showed trends of increasing frequency of occurrence and increasing mean number of epibionts with increasing shell age. Crab-shell age was a significant factor in determining the number of epibiotic species on crabs; the area of origin was not a significant factor. Epibionts are likely to be of limited use as a management tool, because of difficulties in accurately assessing the age composition of commercial samples and the likelihood of temporal and geographic variation in recruitment of epibiont organisms. However, epibionts are probably a significant factor in the population dynamics of C. bairdi and, hence, worthy of further investigation.