Limitations and applications of macroscopic maturity analyses: a comparison of histological and visual maturity for three west coast groundfish species

Accurate maturity schedules are critical to ensure that stock assessment models can track changes in spawning stock biomass. To generate updated maturity estimates, the Northwest Fisheries Science Center’s Fishery Resource Analysis and Monitoring Division instituted a reproductive biology program in 2009. This program uses histological analysis of ovaries to determine maturity, a technique that is more reliable than the traditional macroscopic method but is also time-consuming and expensive. As macroscopic maturity data are still being collected by multiple agencies on the US west coast, most prominently the Oregon Department of Fish and Wildlife (ODFW), we evaluated the usefulness of these macroscopic maturity recordings by verifying their accuracy using histological methods. Two species in this study, arrowtooth flounder ( Atheresthes stomias ) and canary rockfish ( Sebastes pinniger ), representative of west coast flatfishes and rockfishes ( Sebastes spp.), had high correspondence between length at 50% biological (physiological) maturity (L 50 ) evaluated histologically and macroscopically. Estimates of L 50 for sablefish ( Anoplopoma fimbria ), a representative west coast roundfish, varied significantly between macroscopic and histological methods. Functional maturity (potential spawners in a given year) determined via histology did not correlate with macroscopic maturity for any studied species. In its current form, macroscopic maturity collections are insufficient for assessments of species with significant reproductive complexities but have limited application in assessing changes in maturity schedules over time. However, a lack of standardization among different state departments of fish and wildlife severely hinders any attempt at using macroscopic maturity data to analyze spatial trends in maturity.