Life history characteristics of fjord-dwelling golden king crabs Lithodes aequispina

Abstract

In a n interconnecting system of silled, narrow, steep-walled fjords in northern British Columbia (Canada) 3800 golden king crab Lithodes aequispina Benedict and 184 red king crab Paralithodes camtschatica (Tilesius) were taken between 51 to 569 m In 3 samples over a 10 mo period. Larval retention within the most isolated fjords is suggested as an explanation for the relatively high numbers of L. aequispina and the relatively high (41.0 %) infection level of the crabs by the castrating rhizocephalan barnacle parasite Briarosaccus callosus Boschma. Life history characteristics of king crab species In fjords are related to depth. The normaly continental shelf-and slope-dwelling L. aequispina were found significantly deeper than the characteristically intert~dal to continental shelfdwelling P. camtschatica. Depth stratification of L. aequispina was related to reproductive state among unparasitized crabs and parasitism by B. callosus of the others. Reproduction of unparasitized L. aequispina was continuous and aseasonal. Coexisting female P camtschatica displayed strong synchronous reproduction characteristic of the species elsewhere. I propose that juvenile female L. aequispina recruit in the shallows (usually < 100 m). Females mate and extrude eggs at usually < 150 m and incubate eggs slightly deeper (= 150 to 250 m ) . Spawned out (matted setae) females dominate the unparasitized female population at >200 m and comprise the largest proportion of unparasitized females overall. This last phase may exceed a year in length and is probably followed by upward migration to the level (50 to 150 m) at which the less migratory unparasitized adult males are most abundant. Parasitized male and female L. aequispina behave l ~k e matted setae females and are the largest component of the total crab population from 200 to 400 m.