Pacific Islands Fisheries Science Center (U.S.)

A stock assessment of the main Hawaiian Islands Deep 7 bottomfish complex was conducted in 2018. The assessment used a Bayesian surplus production model fit to bottomfish catch and effort data from commercial catch reports for fishing years 1949-2015. Recommendations from the Center of Independent Experts panel concerning the initial 2014 assessment update were addressed, including improved data filtering and standardization techniques, readdressing assumptions for prior values, the inclusion of a fishery-independent estimate of abundance, and exploration of a single-species assessment model for opakapaka (Pristipomoides filamentosus). The surplus production model for the Deep 7 complex was used to evaluate the risk of overfishing as a function of alternative annual reported catches from fishing years 2018 through 2022. The projections included uncertainty in the posterior distribution of estimated bottomfish biomass in 2015 and population dynamics parameters estimated from the assessment model. The Deep 7 bottomfish stock complex in the Main Hawaiian Islands was categorized as not overfished (where overfished was defined as B/BMSY < 0.844) and not experiencing overfishing (where overfishing was defined as H/HMSY > 1) in 2015. The overfishing limit (OFL), defined as the future amount of reported catch that would yield a P*=50% probability of overfishing ranged from 558-604 thousand pounds depending on future year. The smallest Deep 7 future catch that would lead to a roughly P*=40% chance of overfishing was about 490 thousand pounds. The Bayesian surplus production model developed for opakapaka produced similar overall results to the model for the Deep 7 complex. Results were approximately proportional to the corresponding value in the Deep 7 bottomfish model with biomass over all years scaled by 68%, which was similar to the ratio of opakapaka to Deep 7 from two data sources: the estimate of opakapaka biomass to Deep 7 biomass from the fishery-independent survey (68%), and the overall proportion of total catch biomass of Deep 7 bottomfish comprised of opakapaka (67%)

https://doi.org/10.7289/V5/TM-PIFSC-69

Hawaii

National Marine Fisheries Service (NMFS)