Fall 2007 Update: Silver Hake Cannibalism
The percent diet composition of silver hake eaten by silver hake, i.e. cannibalized, has changed over time. This index of cannibalism denotes three things: 1) changes in the amount of other prey items eaten by silver hake, with an increase in cannibalism suggestive of less suitable food available; 2) changes in the abundance of pre-recruits of silver hake, with 0 and 1 age-groups comprising the bulk of cannibalistic prey eaten by silver hake, with implications for stock-recruitment relationships for these notoriously difficult-to-assess stocks; and 3) potential environmental factors influencing these stock dynamics. The southern stock has had a percent incidence of cannibalism between 10-18% for most of the time series, with only slight increases in recent years. Conversely, the northern stock has exhibited notable increases in cannibalism, with up to 35-40% of the diet cannibalistic in recent years. As silver hake is an important predator of and prey for other species in this ecosystem, it will continue to be important to monitor it’s incidence of cannibalism and stock dynamics.