Measures of habitat quality for Black Sea Bass using oyster aquaculture cages

ABSTRACT Objective Black Sea Bass Centropristis striata are a temperate reef finfish that occupy natural and artificial structured habitats. This study used fish behavior, condition indices, and production estimates to evaluate how oyster aquaculture cages serve as artificial reefs for Black Sea Bass in central Long Island Sound, USA. Methods Underwater video was recorded on oyster farms and a natural rock reef to identify and quantify the behavior of Black Sea Bass that is associated with oyster aquaculture cages and boulders. Juvenile Black Sea Bass were sampled from farms and reefs in Clinton and Milford, Connecticut, to assess individual energy density and relative condition factor as measures of habitat quality. Proximate analysis was conducted to develop a predictive regression for percentage of dry weight and energy density in juvenile Black Sea Bass, which was then applied to estimate energy density in fish that were collected from farms and reefs. The abundance of young-of-the-year Black Sea Bass was used to quantify fish production on the oyster farms. Results Significantly greater shelter and grouping activity were observed on cages than were observed among boulders. Instances of courtship/reproduction in mature fish, escape, foraging, and territorial behavior were statistically similar across the cage and boulder habitats. The condition metrics of energy density and relative condition factor showed no difference in the physiological status of juvenile fish that inhabited farms versus reefs. The enhanced production of Black Sea Bass was estimated to be 4.1 kg/100 cages per year based on higher abundance of young-of-the-year fish on farms relative to the rock reef reference habitat. Conclusions Our results suggest that aquaculture gear provides valuable habitat services that are similar to those obtained via other man-made structures that are considered essential fish habitat for Black Sea Bass throughout their life history.