A brief exploitation of the stone crab Lithodes murrayi (Henderson) off south west Africa, 1979/80

The stone crab Lithodes murrayi was exploited briefly off South West Africa between November 1979 and April 1980, the fishery being terminated when the catch per unit effort fell to an uneconomic level. The extent of the L. murrayi grounds is examined on the basis of catch-per-unit-effort data. The species is largely confined to a bathymetric corridor of 500–700 m off South West Africa. Prior to commercial fishing, there was a densely populated region between 24°00'S and 24°40'S, although the crabs were present in small numbers over a much larger area. Over 90 per cent of the fishing effort was applied in this area of high concentration, accounting for almost 95 per cent by mass of the total catch. Although the catch rate declined, the mean size of exploitable crabs and of undersize crabs stayed virtually constant. Some morphometric relationships and a factor for converting processed crab section mass to whole crab mass have been calculated.