Density and growth in populations of juvenile western rock lobsters, Panulirus cygnus (George)

Abstract

SCUBA divers surveyed populations of juvenile Panulirus cygnus on limestone reefs at Seven Mile Beach and Cliff Head, Western Australia, between 1987 and 1989. Estimates of the density and size structure of populations of early-juvenile P. cygnus had high precision, but their accuracy was lower because visual surveys underestimated the population size. Nevertheless, these estimates may be useful indices of puerulus settlement and the growth, habitat use and population densities of juvenile P. cygnus. Puerulus settlement on collectors correlated well with natural densities of early juveniles on reefs. Densities of juveniles were at least three times greater at Seven Mile Beach than at Cliff Head. However, juveniles grew faster at Cliff Head than at Seven Mile Beach. The density of juveniles in reef ledges was twice that in caves; the density in caves was 10 times that on the reef face.