Vol. 53 - Alaska Resources Library and Information Services

species. The attached invertebrate fauna may, in fact, be the most
important aspect of the habitat, for very few juvenile crabs were found
in samples of bare gravel. Shipboard substrate preference tests were
conducted with age 1+ crabs during the June cruise (see Appendix F).
While far from conclusive, the tests indicated that in the absence of
epifauna, young crabs preferred a medium-sized rock substrate over small
rock, gravel or sand. When small "reefs" of natural epifaunal material
were placed on the previously bare substrates, the highest percentages
of crabs were found on tube worms/sand and mussels/small rock combinations.
The erect bryozoan/ medium rock combination attracted the
smallest percentage of crabs. Crabs were observed during the experiments
feeding directly on the tube worms and scavenging food from the
spaces between mussels.
Further studies are needed to test the relationship between post-larval
survival and refuge habitat. The successful settlement of young-of-theyear
crabs during 1983 was apparently on the habitats described in the
Port Heiden and Kvichak Bay sampling areas. These areas are on the edge
of the area of apparent maximum larval concentration found during June.
Larval transport by water currents is the apparent mechanism determining
the distribution of premetamorphic king crab larvae (Armstrong, et al.
1983b; Haynes 1974; Hebard 1959). It is possible that larvae are
transported by near-surface as well as bottom currents, as indicated by
the diurnal vertical distribution patterns found during this study
(Section 3.2.2). The appearance of young-of-the-year king crabs in the
Port Moller-Port Heiden area between June and September is easily
explained using the available current data that show a slow counterclockwise
movement along the North Aleutian Shelf (Haynes 1974).
More difficult to explain is the occurrence of young-of-the-year crabs
in the upper reaches of Kvichak Bay since pelagic larvae were not found
in that subarea. No current data are available for Kvichak Bay except
the general westward drift of low salinity surface water originating
primarily from the Kvichak and Nushagak Rivers.
395