Effects of predation from pelagic 0-group cod (Gadus morhua) on mortality rates of capelin (Mallotus villosus) larvae in the Barents Sea

摘要

Surveys were carried out in 2002 and 2003 to test whether predation from pelagic 0-group cod (Gadus morhua) juveniles affects mortality rates of Barents Sea capelin (Mallotus villosus) larvae. In 2002, capelin larvae were observed in 17% of the cod stomachs and predation was observed at 19 of 50 stations. In 2003, capelin larvae were observed in 8% of the cod stomachs and predation was observed at 19 of 37 stations. The stomach contents and zoo-plankton samples were dominated by copepods and krill. The number of capelin larvae in cod stomachs increased with increasing capelin larvae abundance and cod length and decreased with increasing stomach content of copepods and prey abundance of krill. The time when capelin larvae could be recognised after ingestion in the cod stomachs was estimated experimentally and depended on predator and prey lengths. The estimated overall predation mortality rate from juvenile cod on capelin larvae was about 1.5% per day for both years and can potentially have a significant effect on the survival of capelin larvae, depending on the overlap in the different years.