Ontogeny of swimming ability in the European Sea Bass, Dicentrarchus labrax (L.) (Teleostei: Moronidae)

Abstract

Development of critical speed (Ucrit) of reared young Sea Bass [6–63 days after hatch (DAH), 4–30 mm body length (BL)] at 18.5–21°C was measured using a swimming chamber. Critical speed increased from a mean of 2 cm s−1 at 6 DAH to 41 cm s−1 at 63 DAH at a rate of 0.6±0.03 cm s−1 day−1. When based on size (BL), Ucrit increased at a rate of 2.0±0.1 cm s−1 mm−1. Relative speed increased from 4.7 BL s−1 at 6 DAH to 13.1 BL s−1 at 33 DAH, and was thereafter 13.5–15.7 BL s−1. Sea Bass larger than about 11 mm (when the caudal fin forms) swam at Reynolds numbers > 1000, and were thus swimming in an inertial hydrodynamic environment. Sea Bass young swim fast enough from about 15 mm (approx. 27 DAH) to influence dispersal outcomes.