Habitat use and growth of juvenile ornate rock lobsters, Panulirus ornatus (Fabricius, 1798), in Torres Strait, Australia

Abstract

Habitat use and growth of juvenile (8–90 mm carapace length, or CL) ornate rock lobsters, Panulirus ornatus, were described with the aid of information from field surveys in Torres Strait and from a laboratory growth experiment. In north-western Torres Strait, small juveniles (<40 mm CL) sheltered in solution holes in the seabed that matched their body size. Most shelters were in limestone pavement and near macroalgae. Larger juveniles sheltered in both solution holes and crevices. Juveniles were found at all depths sampled (3–21 m), and densities of juveniles were uniform over this depth range. The average density of juveniles in the study area in 1992–93 was 63 ha^-1. Size distributions of juveniles sampled during August 1992 to March 1993 showed that early growth was 1·4 mm CL week^-1. A laboratory trial to examine the effect of temperature on growth showed that juveniles grew 31% faster at 30°C (0·88 mm CL week^-1) compared with growth at 26°C (0·67 mm CL week^-1) as a result of shorter moult intervals in large juveniles. Size distributions of juveniles sampled at mid year between 1990 and 1995 showed that 10–20% reach legal size (75 mm CL) about one year after settlement.