SANBI IDentifyIt - Species

Print Fact SheetBronze Whaler - Carcharhinus brachyurus

Family

Carcharhinidae

Geographic location / distribution

Habitat:  Bronze whalers are coastal-pelagic species, preferring inshore and offshore warm-temperate and tropical waters. They range from close inshore in the surf zone to far ofshore, from the sea surface to 400m depths.

The adults prefer deeper waters of the continental shelf between Mozambique and the southern Cape while the juveniles are more common closer inshore off KZN.  They are attracted inshore during the annual sardine run. 

It is thought that 2 separate populations exist in southern Africa, and that the inshore waters of the KwaZulu-Natal coast form the nursery grounds. 

Fishery

Bronze whalers (or dusky sharks) are caught as bycatch in the pelagic shark longline fishery and in the tuna/swordfish longline fishery.

They are also targeted by recreational linefishermen, and the newly born juveniles are commonly caught by shore anglers.

Size limits

Stock status

The dusky shark has one of the lowest intrinsic rebound potentials among shark. Therefore, its exploitation should be conducted with extreme caution and under close monitoring. According to the Natal Sharks Board, each year approximately 117 of all sizes are caught. Catches tend to be the highest during June and July; at this time pregnant females and those which have recently pupped are common.

Fisheries management

Bronze whalers are managed as a bycatch in the tuna/swordfish in the large pelagic fishery, and which are managed by Regional Fisheries Management Organisations. South Africa is a member of ICCAT and a co-operating non-member of IOTC and CCSBT. Although RFMO's manage high seas fisheries, management recommendations and resolutions are implemented by South Africa through national legislation and permit conditions. 

The South African Shark fishery was actually banned at the end of 2009 but vessels are allowed to fish on an exemption permit in 2010/2011. 

The Tuna fishery is managed by a Total Allowable Effort (TAE), meaning that instead of setting a limit on the catch, a limit is set on the number of rights holders allowed to catch tuna. Currently there is a limit of 200 rights holders in SA (including pole and longline).

Longlining is not a very selective form of fishing and many species are caught accidentally on the the hooks. Bycatch species in this fishery include: billfishes (swordfish, marlins etc), seabirds, turtles and sharks. Recent assessments show that eleven species of seabird, four species of turtle and 20 species of shark are caught incidentally by this fishery. The FAO estimates that approximately 28% of the catch is discarded. Local studies indicate that discards comprise approximately 22% of the catch. Bycatch restrictions therefore exist to protect vulnerable species like sharks:

Maturity and Sizes

Bonze whalers are born at a size of 69-100cm; reach maturity from 250-340cm, and will reach a maximum size over 300-400 cm.

Physical description

Identifying characters

 

Other similar species

Carcharodon carcharias - Great White Shark

Isurus oxyrinchus - Shortfin Mako Shark

Prionace glauca - Blue Shark

References

Natal Sharks Board

FAO fact sheets http://www.fao.org/fishery/species/2498/en

Fishery Resource Monitoring System Fact Sheets: http://firms.fao.org/firms/resource/9/en

ICCAT Tuna fact sheets. ICAT Manual. January 2010.

FAO. © 2006-2010. Fisheries and Aquaculture Department. Biological characteristics of tuna/Individual species sheets. FI Institutional Websites. Text by Michel Goujon and Jacek Majkowski. In: FAO Fisheries and Aquaculture Department[online]. Rome. Updated 24 February 2010. [Cited 30 November 2010]. Website: http://www.fao.org/fishery/topic/16082/en