Harvest strategy evaluation for the eastern stock of gemfish (Rexea solandri)

The eastern stock of gemfish in south-eastern Australia is currently assess ed to be overfished and to be depleted below the performance criterion esta blished by the Australian Fisheries Management Authority (AFMA). Assessment s of the stock indicate that there was a substantial decline in abundance d uring the late 1970s and early 1980s and that the year classes spawned at t he end of the 1980s were much weaker than expected from the (estimated) sto ck-recruitment relationship. The performances of a variety of alternative m anagement procedures are contrasted. The factors considered in the operatin g models include uncertainty about historical catches, the comparability of recent survey estimates, the form of the stock-recruitment relationship, w hether variations in recruitment about the stock-recruitment relationship a re auto-correlated, and the quantity and quality of the data available for assessment purposes. The management procedures differ in terms of their dat a needs (survey data only, survey and age-composition data) and their targe t levels. The results indicate that, even though yields from the fishery ar e likely to be low, the benefits of conducting annual surveys exceed the co sts. The value of collecting age-composition data is less clear. Management procedures based on Virtual Population Analysis achieve more variable catc hes and are less likely to satisfy AFMA performance criteria than managemen t procedures based on a Schaefer production model, but they achieve higher levels of "guaranteed" catch for the industry. (C) 1999 International Counc il for the Exploration of the Sea.