Commercial fishingCommercial fishing

Commercial fishing

Despite not being commercially targeted, White Sharks are caught as bycatch on long-lines and in nets of professional fishers, and this is currently suspected to be the largest cause of mortality (Presser & Allen 1995). The actual rate of capture of White Sharks by commercial fishers is difficult to assess and has not yet been quantified (Bruce 1992). This is because captures are not usually recorded, and in many cases, captured sharks are either not landed intact or not landed at all. Estimates of annual capture, based on anecdotal reports, range from less than 10 to 100 per annum in South Australia (Bruce 1992) and 100 to 440 per annum for all fisheries (recreational and commercial combined) in Australian waters (Environment Australia 1996, Standing Committee on Fisheries and Aquaculture 1996).

Commercial fisheries that are known to take White Sharks as by-catch include:

• the Southern Shark fishery;
• the snapper fisheries in Victoria and the Gulf of St Vincent and Spencer Gulf in South Australia;
• the tuna farming industry (White Sharks have been killed after entering cages or harassing stock during capture and transport operations);
• the Western Australian Shark fishery; and
• the Tasmanian Scalefish Fishery.

White Sharks are typically bold and inquisitive in their approach to vessels and fishing gear. This behaviour renders them susceptible to incidental capture through becoming entangled in fishing gear and also to targeted killing (for example being shot at the surface without being hooked). Encounter rates between White Sharks and fishing gear may be high in some areas. Bruce (1992) reported that 30 per centof White Sharks sighted at Dangerous Reef, South Australia, had evidence of previous encounters with commercial fishing gear. It is possible that some cryptic mortality occurs after such encounters and subsequent escape from this gear (Bruce and Stevens 1998). The targeted killing of “nuisance” White Sharks (ie. those interfering with fishing or aquaculture operations for other species) has also been reported by several commercial fishers, however the number of White Sharks that continue to be intentionally taken or killed by people prepared to break the law is unknown.

The number of interactions with the domestic longline industry is not known but may be quantified during an observer program scheduled to be implemented with the suite of actions for the Threat Abatement Plan for the Incidental Catch (or bycatch) of Seabirds During Oceanic Longline Fishing Operations (Environment Australia 1999). White Sharks have also been occasionally reported taken in prawn trawls in South Australia, gill nets set for reef fish in Tasmania and entangled in rock lobster pot lines in South Australia. In the past, commercial fishers have also received large amounts of money from the sale of shark products such as fins and jaws (NSW Fisheries 1997).