DENSITY AND GROWTH IN POPULATIONS OF JUVENILE WESTERN ROCK LOBSTERS, PANULIRUS-CYGNUS (GEORGE)

SCUBA divers surveyed populations of juvenile Panulirus cygnus on lime stone reefs at Seven Mile Beach and Cliff Head, Western Australia, bet ween 1987 and 1989. Estimates of the density and size structure of pop ulations of early-juvenile P. cygnus had high precision, but their acc uracy was lower because visual surveys underestimated the population s ize. Nevertheless, these estimates may be useful indices of puerulus s ettlement and the growth, habitat use and population densities of juve nile 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 H ead. However, juveniles grew faster at Cliff Head than at Seven Mile B each. The density of juveniles in reef ledges was twice that in caves; the density in caves was 10 times that on the reef face.