The Age-Structured Production Model for the South Coast rock lobster population extended to be sex- and area-specific, to fit to catch-at-length data, and to use Pope's approximation

Abstract

The south coast rock lobster resource is modelled using an age-structured-productionmodel (ASPM) which fits to catch-at-length data directly. The model is sexdisaggregated (m/f) and area-disaggregated (A=1,2,3). Population equations have been modified from Baranov equations to Pope’s approximation. This has reduced the number of estimable parameters, and speeded up runtime of the program. Note that the model now includes an option for annual variability in the proportion of recruitment (age 0 lobsters) to each area each year. Though formally there is not interArea movement after this recruitment, in effect this means that there is allowance for such movement, but only for ages less than those which the fishing exploits.