KZN Prawn Trawl

White prawns (Penaeus indicus), brown prawns (Metapenaeus monoceros) and tiger prawns (Penaeus monodon) occur on the shallow water mud banks along the north east coast. Bamboo prawns (Penaeus japonicus) are also occasionally trawled on the St Lucia grounds. These prawn species grow fast and have a life-span of approximately one year. Eggs are carried on the abdomen of females. Larvae hatch during the second half of the year, and are transported by currents into estuaries along the KZN coast, where they remain up to the first quarter of the following year and grow into juveniles. Juvenile prawns move out of estuaries and recruit onto the mud banks, where they grow to maturity and reproduce, thus completing the life cycle.

Deep water species include pink (knife) and red prawns Haliporoides triarthrus and Aristaeomorpha foliacea, langoustines Metanephrops mozambicus and Nephropsis stewartii, red crab Chaceon macphersoni, and deep-water rock lobster Palinurus delagoae. The life cycles of these species are diverse, but some (such as rock lobster) are slow-growing and long-lived, making them more vulnerable to fishing. Little is known about the biology of the deep-water prawns and langoustines.

The KZN prawn trawl fishery is based in KwaZulu-Natal ("KZN") and consists of two components: an inshore fishery (5m to 40m depth) on the Tugela Bank and at St Lucia in an area of roughly 500 square kilometres; and an offshore fishery (100m to 600m depth) extending from Cape Vidal in the north to Amanzimtoti in the south, covering approximately 1 700 square kilometres along the edge of the continental shelf.

Up to the 1960s, trawling was sporadic, but thereafter the sector comprised up to 12 companies and 21 vessels, many of which also fished in Mozambique. Regular statistics were collected from 1988 onwards.

Catches and catch rates of individual species or groups of species fluctuate widely, sometimes as a result of fishing strategy (targeting of specific species) rather than fluctuations in abundance. The abundance of shallow-water prawns depends on rainfall patterns and their effects on the flushing of estuaries where larval and juvenile prawns develop. In general, the last two decades have seen declines in the landings of white prawns, pink prawns, langoustines, rock lobster and red crab.

The fishery is managed using a Total Applied Effort ("TAE") strategy, which limits the number of vessels permitted to fish on the inshore and offshore fishing grounds. A TAE of eight fishing permits has been maintained for the past decade. This TAE has now been decreased to a maximum of seven vessels.

The sector is capital-intensive and its infrastructure, marketing and product distribution are dominated by established companies. The fishery requires specialised trawling vessels and equipment and is suitable for commercial fishing only. Fishing grounds are on the South African continental shelf and no foreign fishing vessels are allowed. Vessels are ex side trawl vessels trawling over the stern with a single net boom vessels trawling with a single or with twin nets per boom, and stern trawlers operating with single, twin or triple nets over the stern. Trawl net sizes range from 25- to 72-metre footrope length, with a minimum of 60mm mesh size measured from knot to knot. Trawling takes place on a 24-hour basis, at speeds of two to three knots and an average drag duration of four hours. Trawlers carry about 15 crew and remain at sea for two to three weeks at a time.

Catches (by mass) of the KZN prawn trawl fisheries consist of roughly 20 percent target species, 10 percent retained by-catch, and 70 percent discarded by-catch. The retained by-catch includes cephalopods (octopus, squid and cuttlefish), molluscs, and substantial quantities of several fish species. The discarded by-catch (juvenile or small fish, low-value crustaceans, elasmobranch