Heavy harvesting of the Durban Metropolitan Area's (DMA) marine resources over many years has reduced the size of the stock of economically valuable species available for harvest. This, in turn, has reduced the value of the commercial and recreational fishing opportunities. Some species such as shad are providing a sustainable harvest. Urban development has, in some cases, impacted on the sustainability of Durban's beaches requiring expensive sand replenishment exercises. Durban's relatively good seawater quality supports a wide range of recreational and tourist activities which support increased quality of life and economic activity.

1) Decline in diversity and economic value of marine resources
The major impact of harvesting on Durban's marine resources has been to reduce the size of the stock of economically valuable species available for harvest. This, in turn, has reduced the value of the commercial and recreational fishing opportunities.

Catch composition of the KwaZulu Natal commercial line fishery in the early (1922-33) and later (1983) parts of this century (van der Elst 1989) Note reduction in endemics!

The reduction in stock has occurred through a process of serial over-fishing. As a preferred target species becomes less available, fishing effort is directed towards a less-favoured species. When this species is, in turn over-fished, effort is directed at yet another species. For example, when catches of fish like red steenbras, poenskop and seventy four declined, slinger, santer, scotsman and englishmen were targeted. When these catch rates declined, fishermen targeted shoaling migrants like king mackerel, geelbek and kobs.

Catch composition of commercial and recreational skiboat fishers along the KwaZulu-Natal coast (Data from Mann-Lang et al. 1997).

This sequential fishing of target species has allowed total catches to be sustained despite rapid declines in catch per unit effort (CPUE) of previously important target species. The CPUE of today's technologically advanced commercial vessels is less than a quarter of that caught by the steam-powered lineboats in the 1920s and 1930s.

Recreational skiboat CPUE has also shown a slow but steady decline, although this has been less marked than in the commercial fishery, because recreational anglers have increasingly targeted gamefishes. Current catch rates of recreational skiboat anglers are about 0.41 fish/angler/hour or 0.79 kg fish/angler/hour (Mann-Lang et al ., 1997).

2) Sustained harvest provided by some species 
Shore angler catches
There has been little change in the overall species composition of shore angler catches during the past 11 years. Generally the CPUE for shore anglers over this period has shown no decreasing trend.

Catch composition of recreational shore anglers along the KwaZulu-Natal coast

Shad is the most heavily targeted fish species along the entire KwaZulu-Natal coast. At times there may be several hundred anglers fishing for shad off a single pier or from a short stretch of beach. Shad and karanteen make up, on average, 84% of recreational shore angler catches. In the years when shad catches are good, the proportion of karanteen in the total catch declines and vice versa.

Invertebrates
The mean catch per outing has remained fairly constant for most invertebrate species for the last 25 years. A stable CPUE is indicative of sustainable exploitation of most of these stocks. This must, in part, be attributed to the regular patrols and enforcement capacity of the KwaZulu-Natal Nature Conservation Service. The values in the graph below relate to the whole province of KwaZulu-Natal, but about 80% of the harvesting occurs between the Tugela River and Port Shepstone. The DMA is a consistently exploited area within this section of coast.

Mean annual recreational harvest of marine invertebrates in KwaZulu-Natal
(Tomalin & Kruger, 1999)

3) Unstable beaches
Coastal urban development has, in some cases, resulted in changing the profile of the DMA's beaches. For example, harbour development in Durban Bay has resulted in unstable beaches to the north. The construction of harbour breakwaters, and the sand trap to the south of the southern breakwater, have interfered with the northward movement of sand that would naturally have replenished the beaches. As a result, the northern beaches need to be replenished by pumping about 280 000 m³ of sand from the sand trap area and spreading it on the northern beaches every year, at considerable financial cost. View this site for more information on the sandpumping scheme.