Comparison of Reef Fish Catch per Unit Effort and Total Mortality between the 1970s and 2005-2006 in Onslow Bay, North Carolina

Abstract

Stock assessments indicate many reef fish species have declined in size and abundance in the Atlantic Ocean off the southeastern coast of the United States. However, commercial fishers often state that stock assessments do not match their observations. We compared fishery-independent catch per unit effort (CPUE) and species composition data between the 1970s and 2005-2006 for reef fishes in the vicinity of Onslow Bay, North Carolina. Additionally, total mortality (Z) was estimated by means of a length-based catch-curve analysis. Effort (drops) by rod and reel focused on three sites, two inshore (30 m deep) and one offshore (125 m). The CPUE was compared between periods within each site and larger area (inshore, offshore). The CPUEs of red porgy Pagrus pagrus, vermilion snapper Rhomboplites aurorubens, black sea bass Centropristis striata, and gray triggerfish Balistes capriscus were greater in the 1970s than in 2005-2006 at specific capture sites. Conversely, the CPUEs of red grouper Epinephelus morio, white grunt Haemulon plumieri, and bank sea bass C. ocyura were greater in 2005-2006 than in the 1970s. The CPUEs of snowy grouper E. niveatus, blueline tilefish Caulolatilus microps, and gag Mycteroperca microlepis remained steady or increased between periods. Estimates of Z for snowy grouper, blueline tilefish, red porgy, white grunt, and vermilion snapper were generally greater in 2005-2006 than in the 1970s. Apex species caught in the 1970s but not in 2005-2006 included red snapper Lutjanus campechanus, silk snapper L. vivanus, warsaw grouper E. nigritus, and speckled hind E. drummondhayi. Catch rates and composition may have differed owing to differences in captains' skills and electronics despite efforts to standardize the fishing methods between periods. Estimates of total mortality are generally inconsistent with fisher observations and agree with recent stock assessments concluding that important reef species are overfished. Altogether, our results suggest that fishing and possibly other variables have affected the abundance and mortality of major species in this fishery.