Substrate preference in age-0 red snapper, Lutjanus campechanus

We tested age-0 red snapper, Lutjanus campechanus, for sand or shell substrate preference in a circular tank (1.5 m diameter × 0.6 m deep). The test tank was divided into two equal areas of whole oyster shell or sand substrates. All trials were video taped for 20 to 25 min. Tapes were viewed on a monitor and locations of all fish recorded and timed with respect to substrate. Mean ± SE time on shell was 11.6 ± 0.5 sec (4 fish trial^–1) and 13.8 ± 1.1 sec (1 fish trial^–1). Mean ± SE time on sand was 9.7 ± 0.4 sec (4 fish trial^–1) and 8.9 ± 0.5 sec (1 fish trial^–1). Fish spent significantly more time on shell compared to sand substrate in four-fish trials (paired t-test, p < 0.10) and also in single-fish trials (paired t-test, p < 0.05). Shell substrate may offer increased food and shelter for age-0 red snapper compared to sand substrate. However, a preference for shell substrate in the natural habitat may occur only during the nursery period, because as fish grow (> 100 mm TL) in the late fall they probably outgrow the shell habitat.