Egg cannibalism in Barents Sea capelin in relation to a narrow spawning distribution
Abstract:The spawning distribution of Barents Sea capelin Mallotus villosus off northern Norway in 2002 was restricted to a narrow area at the easternmost spawning grounds. There was an increase in abundance and a marked shift in aggregation area from east towards west during 11 March to 4 April, as the capelin went from prespawning through spawning to spent stages. The capelin stomachs were either empty or contained capelin eggs, often mixed with sand. Both the occurrence of cannibals and stomach fullness increased with stage of maturity, being highest in spent fish, and higher in males than in females. No differences were found between cannibals and non-cannibals of the same sex when adjusted for total length (LT), age, LT at age and condition factor. At similar stomach fullness, the females had consumed more eggs than the males. This was attributed to a higher proportion of empty and broken eggs and less sand in females compared to males. In the full stomachs, the mean consumption in females and males was 623 and 334 eggs, respectively, whereas the respective maximum egg consumption was 871 and 683 eggs. The minimum estimates (given no digestion) of mean ± 95% CL egg consumption in spent females and males were 75·4 ± 6·9 and 58·4 ± 12·0 eggs, respectively, implying a minimum mortality of 1–2% of the total egg production caused by cannibalism.
Document Type: Regular Paper
Publication date: 2006-07-01