Temporal variability in the reproductive parameters of deepwater rockfishes in the Gulf of Alaska

Abstract

Reproductive parameters directly influence estimates of stock biomass and therefore affect the determination of catch levels of many federally managed fish species. These parameters can vary over different temporal scales and a better understanding of how and why reproductive traits change will aid in the management of these species. We examined the reproductive parameters of rougheye rockfish, Sebastes aleutianus, and shortraker rockfish, S. borealis, captured in December 2015 and compared them with parameters from an earlier published study. Maturity values in the earlier study were derived from samples collected in from 2008 to 2014 with a concentration of fish collected in the winter of 2009 and 2010. Rougheye rockfish had a smaller length and age at maturity during 2015 (447 mm, 17.7 years) compared to the earlier sampling period (450 mm, 19.6 years), but neither the interaction of length and time period (P = 0.507) nor the interaction of age and time period (P = 0.270) was significant. Shortraker rockfish also had a smaller length at maturity during 2015 (467 mm) compared to the earlier period of time (499 mm) and the interaction of length and time period was not significant (P = 0.830). Relative fecundity for rougheye rockfish was not significantly different between the two time periods (P = 0.444) and this was also true for shortraker rockfish (P = 0.341). Skipped spawning rates were significantly lower in 2015 for both rougheye rockfish (2010 = 37.4 %, 2016 = 21.8 %, P < 0.001) and shortraker rockfish (2010 = 60.0 %, 2016 = 47.0 %, P < 0.001). This study was a first step in examining how reproductive parameters for these species may change over time. A comprehensive approach to examining temporal trends in reproductive parameters will aid in the understanding of how changing environmental conditions are affecting the productivity of commercially important species.