Queensland Stout Whiting Fishery 1991 TO 2002

Abstract

The stout whiting (Sillago robusta) fishery in southern Queensland is restricted to offshore waters between Caloundra and Sandy Cape in depths ranging between 20 and 50 fathoms. The fishery consists of five licensed trawlers (T4 endorsement). The fishery is managed by means of a ‘industry agreed’ yearly Total Allowable Catch (TAC), which is reviewed annually and divided equally among the vessels. The TAC quota was set at 1000 tonnes for the managed area in 2002.
The stout whiting resource was assessed using a newly developed age-structured model, along side with the previous virtual population and surplus production models.
The new model was tuned simultaneously to standardised monthly-catch-rates and yearly patterns in the stout whiting catch age-structure. The limit reference point B/K
(the ratio of exploitable biomass in 2002 to the exploitable component of the virgin carrying capacity) was estimated to be at about 0.19 (B/K less than 0.2 is generally accepted as high risk of over exploitation). The results from all three models should be viewed cautiously as their uncertainty is high. Given the high uncertainty, any increase in TAC above 1000 t has high risk. In the last four years total catch has varied between 1178 t and 498 t. This year’s assessment has shown no increase in
recruitment and biomass after the catch levels of 881 t in 2000 and 855 t in 2002. The management strategy evaluation suggests this years TAC should range between 700t and 900t depending on the target management objectives of risk and yield from the fishery (Table 3.6). This Table 3.6 should be used to guide the decision on TAC setting and to understand how best to compromise the issues of risk (over fishing) and optimising yield (maximising catch and value in the fishery). Summary of the assessment is given in Table 1.1.