Thirty years of monitoring traditional fish trap catches at Kosi Bay, KwaZulu-Natal, South Africa, and management implications

Abstract

The catches of the traditional fish traps in the Kosi Bay estuarine lakes were monitored over a 30-year period from 1981 to 2010. Monitoring data were used to provide estimates of, and insights into, catch size and species composition as well as seasonal and annual cycles of catch abundance. Over 1.2 million fish, comprising 43 species and 23 families, were estimated to have been caught during the study period. Tag-and-release data were used to estimate the impact of trap fishing on fish stocks and comparisons were made with recreational fishing to indicate overall fishing pressure and the sustainability of the fishing. Trap numbers remained fairly similar from the first year of monitoring (1981) until 1994, but thereafter they more than trebled by 2001; although numbers decreased after this, they remained well above earlier levels. During this period, recreational angling was an important factor, and gillnetting — both legal and illegal — added to the fishing pressure. Information from the fish trap monitoring, together with results from fish mark and recapture studies, suggest a very high, and possibly unsustainable, catch rate that requires management intervention to return them back to historical and sustainable levels.