Over 2,000 species of fish are found in the waters around South Africa; most are tropical and subtropical and about 16 percent are endemic, which means that they are found nowhere else in the world. Fish species range from tiny gobies to huge whale sharks, and include both bony fish and cartilaginous fish – the sharks and rays. Commercial, subsistence and recreational fisheries in South Africa catch more than 630 marine species, most of them fish species. Traditional methods of monitoring and management of fish species have proven to be inadequate for certain species and regulations are often difficult to enforce effectively. This has meant that the stock status of only 41 species is known. Of those 41 species, 25 are considered to be overexploited, collapsed or threatened.
Globally MPAs are increasingly being used as an additional management tool to ensure sustainable use of many of fish species, particularly slow growing, resident species. There is a substantial body of research that demonstrates the effectiveness of MPAs in fish conservation in South Africa. Most of this research has been undertaken in our coastal MPAs such as De Hoop, Tsitsikamma (the oldest), Dwesa-Cwebe, Pondoland and iSimangaliso. In all of these MPAs the abundance of linefish inside the zoned no-take areas is far higher than in the adjacent exploited areas and the size of many of the recreationally and commercially important linefish species is also significantly greater within the no-take areas. There is thus conclusive evidence that no-take MPAs help to protect important linefish species.
Many offshore MPAs contribute towards the management of commercially important fish species such as hake, kingklip and sole. The Agulhas Mud MPA protects some of the habitat of the Agulhas sole, while Port Elizabeth Corals MPA contribute towards the protection of kingklip, one of South Africa’s most valuable fishes that aggregate to spawn here. Protection of rough grounds in Brown's Bank Complex and Namaqua National Park MPAs will assist hake populations that spawn in these areas. Even highly migratory species like tuna benefit from MPAs. The Agulhas Front MPA is within an Ecologically and Biologically Significant Area (EBSA) recognised for its role in the life history of tuna and other fishes. The Agulhas Bank Complex MPA provides protection for migratory species such as geelbek and resident linefish such as red stumpnose, red roman and spawning aggregations of endangered red steenbras.
Unlike humans and most mammals, whose breeding ability declines after a certain age, in many fish species, the older and bigger the females get, the more fertile and productive they become. Where fish are allowed to mature undisturbed in a no-take area, the returns increase exponentially as their number of offspring increases. These young fish can move outside the no-take area into exploited areas. This flow of benefits is known as the “spillover effect” where fish populations build up inside the MPA and eggs and larvae from the large breeding adults can restock fishing grounds. This is extremely important as fishermen can benefit directly from this spillover in adjacent exploited areas. In many ways it is similar to having money in a bank account which, if carefully managed, can grow and produce interest which can be sustainably used without plundering the capital.