Interannual variation and seasonal changes in black rockfish (Sebastes melanops) diets off Newport, Oregon

As revealed by the diets of upper level predators, variable oceanographic conditions and extensive fishing may alter the assortment and abundance of mid trophic level prey items. The commercially important black rockfish (Sebastes melanops) is an example of an upper level predator that preys on forage fish species such as smelt and sandlance. By collaborating with commercial fishermen in the local city of Newport, Oregon, the stomachs of these predators were obtained to compare the interannual and seasonal changes of their diets between 2010 and 2011. They were also utilized to determine if the diets can point to fluctuations in prey availability. Important prey items include Cancer magister megalopae and adult Mysid spp in May, Mysid spp, Cancer spp, and adult Thysanoessa spinifera (krill) in June, and juvenile fish in July. Preliminary results indicate a large variation in diet between years and seasons, with Sebastes melanops acting as opportunistic feeders. Diet analysis will ultimately provide more information on the predator-prey dynamics needed to create fisheries management plans that better capture the complexity of this marine ecosystem.