Behavior of Juvenile Black Sea Bass, Centropristis striata (Linnaeus) on Oyster Reefs

Abstract

The substrate preferences of juvenile black sea bass Centropristis striata (Linnaeus) was tested in a circular tank (1.5 m diameter×0.4 m deep) divided into two equal areas of oysterrelated (oyster reef and whole oyster shell) and sand substrates. All trials were video taped for 20 min. Tapes were viewed on a monitor and locations of all fish recorded and timed with respect to substrate. Mean±SE times on oyster shell were 18.1±2.0 min (1-fish trial-1) and 17.5±1.7 min (5-fish trial-1). Mean±SE times on sand were 2.0±1.0 min (1-fish trial-1) and 2.5±1.7 min (5-fish trial-1). Black sea bass juveniles showed a significant preference for oyster reef and shell over sand substrate in single-fish trials (paired t-test, P/0.05) and also in five-fish trials (paired t-test, P/0.05). Mean±SE times under oyster reefs were 16.6±2.0 min in single-fish trials and 10.7±2.3 min in five-fish trials. Mean numbers of movements among oyster reefs were 1.1±1.0 in single-fish trials and 11.5±3.1 in fivefish trials. Fish spent significantly less time under oyster reefs in five-fish trials, compared to single-fish trials (paired t-test, P/0.05) and they moved more frequently in five-fish trials than in singlefish trials (paired t -test, P/0.05). Significantly higher competition for a refuge in five-fish trials may induce less time under oyster reefs as well as frequent movement of black sea bass juveniles on shell substrate.