Habitat preferences and behaviour of newly settled Jasus edwardsii (Palinuridae)

Abstract

Any attempt to enhance production of rock lobsters by increasing survival at and soon after settlement, or by catching pueruli for on-growing or out-planting, requires knowledge of settlement behaviour and the habitat of settlers and young juveniles. I investigated biotic and physical factors important in habitat use by recently settled Jasus edwardsii in laboratory tank experiments. Both pueruli and first-instar juveniles sought shelter over and above conspecifics or any of the other marine life tested. They preferred conditioned refuges over those unconditioned, horizontal apertures over upward-facing vertical ones, and rough surfaces over smooth. Although some structurally complex seaweed and bryozoan species seemingly provide suitable refuge, they were less often used by the young lobsters than were hard-walled shelters. These results are generally consistent with the few field observations available and the results of experiments with collectors. Both pueruli and first-instar juveniles are capable of almost completely burying themselves in sand, but they are intolerant of deep silt. Any structures deployed to catch pueruli or to increase survival of recently settled J. edwardsii should ideally provide wellconditioned, firm but rough-walled, horizontal holes or crevices. The availability of such situations in nature may strongly influence lobster survival and abundance, and hence productivity.