High abundance of larval rockfish over Cobb Seamount, an isolated seamountin the Northeast Pacific

The larval fish community in the region of Cobb Seamount (500 km west of Or egon) is dominated by myctophid species commonly encountered in the subarct ic North Pacific. However, during a survey in June 1992, the ichthyoplankto n community within 30 km of the seamount summit was almost completely domin ated by larvae of various rockfish (Sebastes) species. Given their very sma ll size (and hence very young age) and the fact that they occurred only rar ely in samples collected >30 km from the seamount summit, we conclude that these Sebastes larvae were produced locally over Cobb Seamount. Previous st udies have shown that the Cobb fish fauna is dominated by various Sebastes spp. and that, unlike other fish present on the seamount, the rockfish popu lations may be self-recruiting. We suggest that a persistent clockwise (i.e . downwelling) eddy, consistent with a stratified Taylor cone, plays a crit ical role in retaining larval rockfish over Cobb Seamount and may con, trib ute to the process of self-recruitment. The key to the success of rockfish on Cobb and other shallow Northeast Pacific seamounts seems to be linked to their viviparous life history.