COHABITATION IN THE SPINY LOBSTER JASUS-EDWARDSII (HUTTON, 1875)

Cohabitation in the southern temperate spiny lobster Fasus edwardsii was investigated on a coastal reef in north-east New Zealand over 3 years. During daytime most lobsters occurred in aggregations of up to 105 individuals. Fifty percent of lobsters occurred in the 9% of shelters containing greater-than-or-equal-to 7 individuals. There was not an equal occurrence of categories of lobsters (based on size, sex and reproductive status) in shelters. juveniles (<85 mm CL) occurred in only 10% of shelters while mature females (>85 mm CL) occurred in 61%. Every lobster category occurred in shelters significantly less frequently than expected, based on abundance, indicating frequent cohabitation with peers. Cohabitation varied with lobster size and sex, and season. The smallest size classes (<30 mm CL) were more solitary than larger juveniles (30-70 mm CL) which almost always cohabited. Cohabitation decreased to 64% in lobsters 175 mm CL. Categories of lobster showed different patterns of cohabitation. juveniles (<85 mm CL) cohabited in a few large aggregations, principally in shallow reef habitats, with no seasonal change in cohabitation. Conversely, large reproductive males (>140 mm CL) were often solitary and demonstrated clear seasonal trends in cohabitation, independent of population density. Among mature females (>85 mm CL) and large reproductive males the proportion cohabiting with peers was highest during the austral summer and least in June, the peak of mating. During this period reproductive males were randomly distributed, rarely with >1 per den, and the number of mature females cohabiting with reproductive males increased with male size. The relative importance of depth, abundance and season in regulating the distribution of F. edwardsii among dens varied with lobster size and sex.