The sea mullet (Mugil cephalus) occurs around much of the Australian coastline, as well as in many temperate and subtropical areas worldwide. In NSW waters, sea mullet are found primarily in estuaries and inshore waters, although they also occur in the freshwater reaches of coastal rivers. Within estuaries, sea mullet are found in association with shallow weed beds and bare substrates (Smallwood et al. 2013).

Sea mullet is an important species in many coastal fisheries of Australia with a long history of stable landings and catch rates is evident for both the estuary and ocean fisheries. Populations on the Australian east and west coasts are genetically distinct (Smith and Deguara 2002). The biological stock structure of Sea Mullet off Western Australia is likely to be complex, although limited tagging and genetic studies suggest mixing of fish throughout the lower west coast region, where the majority of the catch is taken. Therefore, a single Western Australian biological stock is assumed here. Stock status for Sea Mullet is reported at the level of individual biological stocks (Smallwood et al. 2013).

Sea mullet inhabit coastal waters and estuaries in tropical and temperate waters of all seas of the world and in WA are common from Esperance to Port Hedland. Sea mullet along the lower west and south coasts of WA are considered to represent a genetically homogeneous stock (Johnston et al. 2015). Taking a precautionary management approach, sea mullet in the West Coast Bioregion (Fletcher and Santoro 2015), which includes the PHE, is managed as a separate stock from populations in the neighbouring Gascoyne Coast and South Coast bioregions.

Sea Mullet occurs in all coastal regions of Western Australia, but commercial targeting of the species is mainly restricted to waters from Shark Bay southwards. Sea Mullet is managed separately in the four Western Australian bioregions, although the level of connectivity between the different populations is unknown (Smallwood et al. 2013).