Resilience and exploitation of mussels: the convergence of history and biology leads to overexploitation of a key marine natural resource

Abstract

History, geography, and biology have converged to establish two west–east gradients along the southern coast of South Africa, one biological, one human. Historically, the Nguni-speaking peoples of the country spread from east to west along the coast, with the later European settlers moving west to east. The two peoples met in the vicinity of the Great Fish River. Under apartheid, two “homelands”, Ciskei and Transkei, were established leading to starkly different contemporary patterns of settlement and economic development. Poverty and reliance on marine natural resources, particularly mussels, are markedly higher in these former homelands. Mussel recruitment diminishes from west to east in South Africa, and the coastline of these former homelands, dominated by the oligotrophic Agulhas Current, exhibits low primary productivity and particularly low recruitment. The result is a west–east gradient of greater poverty and dependence on marine natural resources mirrored by decreased recruitment and biological resilience of mussel populations. Similarly, mussel recruitment and growth are greater on inaccessible wave-exposed shores and toward the low shore where exploitation is more difficult. The mismatch across large and small scales between where marine resources are most able to sustain exploitation and where exploitation is most intense leads to serious environmental degradation.