Potential Mechanisms Influencing Growth and Survival of Young of the Year Pacific Ocean Perch Prior to Benthic Settlement

Pacific Ocean Perch (POP) are a commercially valuable species with a dominant biomass in the Gulf of Alaska. POP are ovoviviparous and release their young into the water column on the continental slope in the late spring in the GOA, but we know little else of their early life history.  We provide the results of 4 years of integrated surveys aimed at understanding their early life history and the mechanisms driving their growth and survival. Larvae POP are advected offshore after parturition and inhabit the mixed layer in the epipelagic for the summer. Otolith measurements of daily growth indicate offshore transport rates as high as 3.2 km per day. This transport is important because offshore epipelagic habitats are warmer and have deeper mixed layer depths than nearshore habitats. POP sampled offshore were rarely co-located with predators (e.g. salmon) and competitors (e.g. pollock) suggesting this habitat provides enhanced access to prey and improved growing conditions.  About midway during their epipelagic residence POP shift energy allocation strategies from favoring somatic growth to lipid storage with energy density peaking just before settlement begins. We conclude that habitat features afforded by the offshore epipelagic are important to production of POP juveniles.