Migration of the Ornate Rock Lobster, Panulirus ornatus (Fabricius), in Papua New Guinea

Abstract

In Papua New Guinean waters, there are two reef fisheries and a trawl fishery for the ornate rock lobster, P. ornatus. A single stock of lobsters is the basis of all three fisheries. The migration pattern of this species was determined by tagging 6077 lobsters, of which 719 (11 .8%) were recaptured. In August-September each year, adult lobsters in northern Torres Strait undertake a mass migration across the Gulf of Papua to spawning grounds at the eastern limit of the Gulf. Lobsters walk across an open sand-mud seabed for 2-3 months at an average speed of 6.1 km day-1. The maximum recorded distance was 511 km. No return migration was detected and probably there is a high mortality of lobsters after spawning. The reason and stimulus for this mass migration are discussed. Larval recruitment is generally to a different area from the adult population in northern Torres Strait, necessitating a subsequent migration of juveniles into the adult habitat. Once these juveniles have moved into the northern reef systems, they remain in the area, usually within a specific reef complex, for 1-2 years before undertaking the mass migration into the Gulf of Papua.