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

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 conse rvative estimate of the number of species involved. Seven species or c ollective taxa occurred on the exposed outer surface of greater than o r equal to 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 occ urred in the branchial chamber. Of these, Triticella sp., Alcyonidium sp., and mucoid-tube polychaetes were found in greater than or equal t o 50% of 25 branchial cavities examined. Three species (Triticella sp. ; a small, white flatworm; and Hiatella arctica) were found only in th e branchial chamber. Our data showed trends of increasing frequency of occurrence and increasing mean number of epibionts with increasing sh ell age. Crab-shell age was a significant factor in determining the nu mber of epibiotic species on crabs; the area of origin was not a signi ficant factor. Epibionts are likely to be of limited use as a manageme nt tool, because of difficulties in accurately assessing the age compo sition of commercial samples and the likelihood of temporal and geogra phic variation in recruitment of epibiont organisms. However, epibiont s are probably a significant factor in the population dynamics of C. b airdi and, hence, worthy of further investigation.