Response of diurnal and nocturnal coral reef fish to protection from fishing: An assessment using baited remote underwater video

Abstract

Diel variation is known to alter the compositionand structure of reef fish assemblages. What is unknown ishow nocturnal fish assemblages respond to closed fisheryarea management. Diurnal and nocturnal reef fishassemblages at the Houtman Abrolhos Islands, WesternAustralia, were studied using baited remote underwaterstereo-video systems (stereo-BRUVs). Surveys were conductedduring the day and at night (using blue illumination)from three sites inside and three sites outside a closedfishery area (CFA). The relative abundance of 116 fishspecies from 41 families was recorded. Significant changeswere observed in fish assemblage structure from day tonight (driven by high dispersion at night) and in areas openversus closed to fishing (driven by increased abundancewithin the CFA). The effect of protection from fishing wasconsistent for both diurnal and nocturnal fish assemblages.Closer examination of six targeted fish species showed that their response to diel changes and the absence of fishingpressure varied from species to species. The targeted fishesPagrus auratus and Glaucosoma hebraicum were sampledduring the day and at night with both species respondingpositively to protection from fishing. Results suggest thatthe inclusion of diurnal and nocturnal fish assemblage datawill provide an improved ability to assess the effectivenessof closed fishery area management.