Walleye Pollock Reproductive Development Described through Image Analysis Software: Implications for Stock Assessment

Walleye pollock (Gadus chalcogrammus) supports the largest commercial groundfish fishery off Alaska. Walleye pollock fishery managers apply harvest control rules to annual estimates of spawning stock biomass (SSB) from age-structured stock assessments to set catch quotas. However, stock assessments typically do not account for annual and regional variability in the seasonal timing and location of maturation and spawning. Walleye pollock are described as a partial-batch spawning species where ova are released in batches over the course of a month though there appears to be plasticity in oocyte development and spawning phenology between different spawning locations. Here we present analysis of 20 years of maturity collections using image analysis software and histological to describe the maturation process. These results also suggest that spatially explicit information of pollock maturity has implications for estimates of stock productivity and therefore the harvest control used to manage this valuable fishery.