IDENTIFICATION: Orange-brown body; tail-fan orange with blue and green. The thorax is covered with spines, and the front of the carapace has two large spines and a central projection (rostrum) between the eyes. SIZE: 30 cm.

BIOLOGY: This is the most important commercial rock lobster in southern Africa, 2200 tonnes being harvested in 1992. In past years the industry took up to 10 000 tonnes, but steadily eroded the supply of animals of legal size (then 89 mm carapace length). Jasus grows slowly. Males of 80 mm are 5-7 years old; Females about 12 years old. Stunted growth in 1990-92 severely reduced catches. To spread the fishing effort over a wider size-range, the size-limit was reduced to 80 mm in 1992 and (for commercial fisheries) to 75 mm in 1993. Jasus is intolerant of low oxygen levels and, on the northern West Coast, regularly becomes concentrated inshore to avoid water that has little oxygen. Occasionally hundreds of thousands are stranded on the shore.

Jasus feeds on mussels, urchins and even barnacles, and is capable of eliminating many species in areas where rock lobsters are abundant. Rock lobsters are eaten by octopus, dogsharks and seals.