SEMINAR: OI Seminar Series - Cordelia Moore

Title: Does my bottomfish look big in this?

Abstract: Hawai‘i's deepwater handline fishery is the second most valuable fishery in the state. It targets a suite of bottomfish species including snappers (Lutjanidae), jacks (Carangidae) and an endemic grouper (Epinephelidae). Many of these species have a relatively high age of maturity, long life span and slow growth rate making them highly susceptible to overfishing. Following a steady decline in catch rates, and evidence of overfishing, the State of Hawai‘i implemented a network of bottomfish restricted fishing areas (BRFAs). These were designed to protect 20% of the population by protecting 20% of their essential fish habitat (those waters and substrate necessary for fish spawning, feeding or growth to maturity). Our research evaluated bottomfish relative abundance and size distribution both inside and outside six of the BRFAs. No differences were detected in species relative abundance. However, evaluation of size frequency distributions found two species (Etelis coruscans and Pristipomoides filamentosus) to be significantly larger inside the BRFA at Ni‘ihau. This BRFA is one of two ongoing BRFAs offering 10 years of protection. No positive effects of protection were detected for the second ongoing BRFA off Hawai‘i. Instead, two species (P. filamentosus and Pristipomoides sieboldii) were significantly larger outside the BRFA. In contrast to Ni‘ihau, the BRFA off Hawai‘i originally included less preferred habitat and is next to the second largest port in Hawai‘i offering greater access, higher population pressure and more problematic enforcement. This study highlights the time it may take a long lived and slow growing species to show a detectable response to protection and that size distribution analyses can detect these more subtle changes. In addition, it demonstrates the importance of integrating biological, sociological and environmental context when interpreting results.

Cordelia Moore is a new UWA-AIMS-CSIRO Research Associate and will be presenting research conducted at the University of Hawai‘i at Mãnoa.