Stock assessment of the Australian east coast grey mackerel (Scomberomorus semifasciatus) fishery.

Abstract

This stock assessment used an age structured model with a yearly time step and age based selectivity to estimate the population size and sustainable harvest limits for Queensland east coast grey mackerel. Separate models were assessed for the north-east and south-east stocks. Data inputs included total harvest, standardised catch rates, age and length structures. For both stocks, unfished biomass was relative to 1960-61, before substantial fishing pressure began.
 
For the north-east stock, model results suggested that biomass declined to 46 per cent unfished, exploitable biomass in 2010-11. The assessment suggests that the north-east stock is currently between 37 and 58 per cent unfished biomass.
 
For the south-east stock the results suggest that biomass declined to 38 per cent unfished biomass in 2010-11. The assessment suggests that the south-east stock is currently between 40 and 61 per cent of unfished biomass.