The Durban Metropolitan Area's growing population has resulted in extensive urban development along the coast. Many residents and visitors use the coast for recreational purposes, and the marine resources are harvested by numerous recreational and commercial boat fishers, shore anglers, spear fishers, seine-netters and invertebrate collectors. Eighteen point sources discharge sewage and industrial effluent into the sea around the Durban Metropolitan Area (DMA).

1) Population growth
The DMA has a population of approximately 2.5 million people, and this is increasing at a rate of 2% per year. A large proportion of this population lives within one kilometre of the coast. This has resulted in housing and other infrastructure such as transport and waste disposal systems being located along the DMA's coast. Many residents and visitors use the coast for recreation and as a source of food. For example, on New Year's Day 1999, over 100 000 people flocked to the beaches between Brighton Beach and the Umgeni River.

2) Increased harvesting of marine resources
The number of people using the DMA's marine resources, and the amount harvested each year, is growing steadily. Fishing, and to a lesser extent invertebrate harvesting, is higher during holiday periods, because Durban is one of the most popular domestic holiday destinations in South Africa. Catches are particularly high in July when both school holidays and the shad season coincide.

Commercial and recreational boat fishing
Before the development of the skiboat, commercial line fishing was carried out from inboard-powered boats that ranged in size from 10 to 20 metres. The development of the skiboat has led to a very rapid growth in the fishing effort directed at all fish stocks. This is because skiboats allow both commercial fishers and recreational anglers to launch from many more places along the coast. The advent of 'rubber ducks' and semi-rigid crafts has also brought the sport of offshore fishing within the reach of many more anglers. More than one third of all skiboat launches along the KwaZulu-Natal coast take place in the Durban Metropolitan Area. Recreational anglers can also go deep-sea fishing on any of about 30 charter boats operating out of Durban Harbour.

Trends in the number of recreational skiboats in KwaZulu-Natal
(from NDSSA and DOT registrations)

Recreational shore anglers
Fish such as shad, karanteen and blacktail are caught by about 55 000 recreational anglers from the shore (Mann et al. 1997). These anglers catch in the region of 0.25 fish/angler/hour or 0.1 kg fish/angler/hour. The average angler outing is about 5 hours and an angler fishes approximately 30 times a year. Thus, shore anglers catch about 1 000 tonnes of fish along the KwaZulu-Natal coast each year. Shore angling effort is particularly high in July when both school holidays and the shad season coincide.

Mean monthly shore angling effort along the Durban Metropolitan coastline, based on
KZNNCS shore patrols 1988-1998 (NMLS data)

Spearfishers
Approximately 3 000 spearfishers in KwaZulu-Natal target a wide range of game and reef fish, particularly king mackerel, queen mackerel, knifejaws and fingerfins.

Seine-netters
Seine-netters in the DMA concentrate on shoaling species like sardines.

Invertebrate harvesting
Large quantities of invertebrate animals like crayfish, mussels, prawns, crabs and red bait are collected from the shore every year, almost exclusively by recreational harvesters. With the exception of crab collectors, invertebrate harvesters make approximately one collecting outing a month for each of the organisms, although there is a trend of gradually declining use of collecting permits in most categories. The average diver catches 4 crayfish on each outing and a mussel collector will harvest 47 mussels on each collecting day. Permits allow for the capture of 15 sea lice and 2 octopus per outing. Generally 43 prawns and 4 swimming crabs are the average catch for each collector outing.

3) Marine disposal of waste
A growing population means an increasing need for waste disposal facilities. Eighteen point sources (including sewerage works outflows and marine pipelines incl Sappi Saiccor) discharge effluent into the sea around the DMA.

The location of coastal effluent discharges along Durban's coast

Sewage outfalls
Together, the Durban Central outfall and the Durban Southern outfall carry in excess of 200 000 m³ of domestic and industrial effluent, which includes sewage sludge, into the sea each day. In addition, the growth of informal settlements has resulted in increasing run-off of untreated sewage and discharge into the coastal environment. The southern metropolitan region, around the Umlaas and Reunion canals, is the most heavily polluted marine area in the Durban Metropolitan Area. At least 14 500 m³ per day of mainly domestic effluent finds its way into the sea from these canals. Several sewage works each discharging 20 000 to 30 000 m³ per day are situated along the Umgeni River. This effluent eventually enters the sea via the estuary mouth.

Industrial outfalls
Industrial outfalls include the SA Tioxide, AECI and SAPPI-SAICCOR pipelines (The SAPPI SAICCOR pipeline discharges at Umkomaas which is not included in the Metropolitan Area. The effluent does, however, impact on the waters of the DMA and for this reason it is included in this report). These pipelines extend 2 to 4 kilometres out to sea. AECI pumps 3 500 m³ of calcium and sodium salts, which include trace levels of mercury, through their pipeline into the sea every day. The adjacent SA Tioxide pipeline adds a further 5 000 m³ of sulphuric acid and ferrous sulphate each day. The SAPPI-SAICCOR pipeline carries approximately 90 000 m³ of lignosulphate into the sea daily. (SAPPI-SAICCOR has recently extended the length of its pipeline and installed a lignosulphonate extraction plant to reduce the impact that the effluent has on the environment). Information in the following table has been sourced from Connell (1998), Schleyer et al. (1996), Tioxide (1998) and the CSIR (1999).