Depletion Based Population Estimates for Western Rock Lobster

Depletion methods examine the decline in catch rate as catch is removed from a closed population. These methods provide a way to estimate original population size before fishing and the residual biomass after fishing and hence exploitation rate. This approach allows long-term changes in catchability and hence fishing efficiency to be assessed in the estimate of exploitation rate. The technique is applied to the western rock lobster fishery in Western Australia for the non-migrating part of the season, March to June. The trends in catchability, residual biomass and exploitation for three zones of the fishery since the 1984/85 season are examined.

Time: completion June 2004