Somerton and Donaldson: Parasitism of Lithodes aequispinus by two species of Careproctus 
873 
Figure 2 
64°N 
62° 
60° 
58° 
56° 
54° 
52° 
50° 
Collecting sites for the 1982 trawl survey (shaded area) and the 1996 commercial catch 
sampling areas in the Bering Sea and Aleutian Islands (unshaded areas). 
Materials and methods 
Golden king crab were sampled 1 1 Julv-25 August 
1982 aboard the FV Rujin Maru no. 8 while it was 
conducting a bottom trawl survey of the benthic re- 
sources along the continental slope of the eastern 
Bering Sea (Fig. 2). All golden king crab were first 
sorted to sex, then measured for carapace length (CL) 
from the base of the eye to the posterior midline of 
the carapace. Females were evaluated for maturity, 
on the basis of relative width of their abdomens, and 
if mature, their pleopods were examined to deter- 
mine whether they were carrying uneyed embryos, 
eyed embryos, or remnants of recently hatched em- 
bryos (egg cases and funiculi), or whether they were 
bare. 
During this sampling, the senior author discovered 
that many of the crabs contained Careproctus - like 
egg masses or larvae within their branchial cham- 
bers. Further inspection of the egg masses and lar- 
vae revealed that there appeared to be two distinct 
types, one with egg diameters or larvae lengths con- 
siderably larger than the other. Several species of 
Careproctus were also captured in the trawls but two 
species, pink and red snailfish, predominated. Gentle 
pressure applied to the abdomens of some individu- 
als of both species resulted in eggs being extruded 
through the ovipositor (Fig. 1) or milt being extruded 
out the genital papilla (Stein, 1980). The eggs of pink 
snailfish were visibly larger than those of red 
snailfish and the egg sizes of both species clearly 
matched the egg sizes found within the crabs. Con- 
sequently, starting on 27 July, 48 consecutive trawl 
hauls were sampled as follows for Careproctus spp. 
and their eggs and larvae. 
All golden king crabs were examined for the pres- 
ence of Careproctus egg masses or larvae clusters by 
removing their carapaces. Each mass was evaluated 
to type (uneyed embryos, eyed embryos, or larvae) 
and species (large eggs and larvae were assigned to 
pink snailfish; small eggs and larvae were assigned 
to red snailfish), and for location (i.e. which side of 
the crab it was obtained). Snailfish were first sorted 
to species, then externally sexed, if possible, by the 
presence of either an ovipositor or a genital papilla. 
Snailfish were then gently squeezed about the abdo- 
men and classified as ripe if either eggs or milt were 
extruded. Thus, the sex could be either known or 
unknown and, if known, the individual could be ei- 
ther ripe or unripe. 
The 1996 incidence of snailfish eggs and larvae 
within golden king crab were assessed by Alaska 
Department of Fish and Game at-sea observers and 
port samplers during the golden king crab fishing 
season in the Aleutian Islands and eastern Bering 
Sea. Female and small (<135 mm-CL) male golden 
