Feeding habits of the false southern king crab Paralomis granulosa (Lithodidae) in the Beagle Channel, Tierra del Fuego, Argentina

Abstract

Stomach contents of 282 false southern king crabs (Paralomis granulosa), between 10 to 90 mm CL from the Beagle Channel (Golondrina Bay and Roca Mora), Argentina, were examined by the frequency of occurrence method of analysis and by a food index. Roca Mora is an area where juveniles (<50 mm CL) dominate and in Golondrina Bay adults (>60 mm CL) are common; in this last area sexual segregation was also observed. The principal food groups for crabs of Golondrina Bay were algae, molluscs, crustaceans, bryozoans and foraminiferans; for crabs from Roca Mora the natural diet consisted of three major food groups: hydrozoans, echinoderms and foraminiferans. The relative frequency of different prey groups varied in relation to the size, season and sex. There were no significant differences in the quantity of food consumed by sexes in both areas. Generally small crabs (<40 mm CL) contained more food than large crabs (>50 mm CL). Juveniles consumed a greater amount of food during winter and spring. In summer (moulting period), juveniles had the highest vacuity index. Adults consumed minor amounts of food during autumn, before the spawning-moulting-mating period when the vacuity index was higher (spring).