Sandbar Shark Carcharhinus plumbeus

Western Australian biological stock

In Western Australia, Sandbar Shark is targeted by the West Coast Demersal Gillnet and Demersal Longline Fishery, and taken in lesser quantities by the Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery⁴. It was also previously targeted by the Western Australian North Coast Shark Fishery⁵. The Western Australian stock assessment uses current and historical data from all of these fisheries. Minor catches historically reported from the Offshore Net and Line Fishery (Northern Territory) are assumed to be from the western biological stock, but these are not explicitly included in assessments of this stock.

Because of the longevity of Sandbar Shark and the age-specific nature of targeted fishing mortality, a sufficiently long time series of catch-per-unit-effort data is not yet available for dynamic stock assessment modelling. Assessment of this stock has therefore been undertaken using empirically derived estimates of fishing mortality between 2001 and 2004, and demographic modelling techniques^6,7.

Demographic modelling indicated that combined levels of fishing mortality in Western Australian targeted shark fisheries, nontarget commercial fisheries and the recreational fishing sector became increasingly unsustainable between 2001 and 2004 (when catches peaked at 918 tonnes [t]) and had probably exceeded sustainable levels since 1997–98. These conclusions are supported by fishery-independent survey data that indicated declining breeding stock abundance between 2002 and 2005^5,6.

Since 2010, Sandbar Shark catches have remained well below the levels that will allow a gradual recovery of the breeding stock. The expected reductions in recruitment from previously excessive exploitation of the breeding stock are likely to be ameliorated by significant reduction in targeted fishing effort. Therefore, although the breeding stock is considered to be close to the minimum acceptable limit (40 per cent of unfished biomass), current levels of fishing are considered suitably precautionary to ensure the recovery of this biological stock.

On the basis of the evidence provided above, the biological stock is classified as a transitional–recovering stock.

Eastern Australian biological stock

In New South Wales, whaler sharks (Carcharhinus spp.), including Sandbar Shark (C. plumbeus), have historically not been adequately identified and reported at a species level in commercial catch logbooks. However, observer data indicate that Sandbar Shark represents the largest single-species component of catches in the Ocean Trap and Line Fishery (New South Wales), at 35 per cent of the overall shark catch⁸. Insufficient information is available to determine status for any of the whaler shark species in New South Wales, including Sandbar Shark⁹. The net fishery of the East Coast Inshore Fin Fish Fishery (Queensland) contributes minimal quantities (less than 2 t per year) to the overall eastern Australian harvest of Sandbar Shark.

On the basis of the evidence provided above, the biological stock is classified as an undefined stock.