Updated Maturity Estimates for Flatfishes (Pleuronectidae) in the Eastern Bering Sea, with Implications for Fisheries Management

Abstract

AbstractFemale Yellowfin Sole Limanda aspera, Alaska Plaice Pleuronectes quadrituberculatus, and Flathead Sole Hippoglossoides elassodon were collected from the eastern Bering Sea during known prespawning, spawning, and postspawning periods in 2012 and 2013, and their ovaries and otoliths were sampled for use in histological analysis to update historical maturity estimates. For fisheries management, new information on maturity at age can lead to possible changes in estimated reproduction potential (measured as female spawning stock biomass [SSB]) and values of fishing mortality reference points. Our analysis indicated that Yellowfin Sole currently mature at an age similar to that estimated in a study conducted 20 years ago. An evaluation of impacts on the stock assessment indicated that updated estimates of Yellowfin Sole SSB were over 7% higher, but the reference points only changed slightly. The first histologically derived maturity estimates for Alaska Plaice were close to the anatomically derived estimates (visual assessments from 1987), resulting in a marginal decrease (5%) in SSB, but changes in reference points were near 10%. Based on the new maturity estimates for Flathead Sole, SSB estimates increased by 7% compared with estimates currently used in the stock assessment, which relied on maturity data collected in 1999 and 2000. The change in Flathead Sole SSB was concomitant with changes of 16–18% in fishing mortality reference points. Our results indicated minimal differences from historical maturity estimates after re‐examination, but in some cases those differences led to relatively large changes in the respective reference points, underscoring the reference points' sensitivity to changes in maturity. Incorporation of these new maturity estimates into the stock assessment process provides valuable updated information for fisheries managers. However, a more comprehensive sampling program is needed to investigate the spatial and temporal aspects of reproduction for each species.Received November 13, 2014; accepted September 3, 2015