Characteristics and value of the Thukela Banks crustacean and linefish fisheries, and the potential impacts of changes in river flow

  • JK Turpie
  • SJ Lamberth

Abstract

This study describes the Thukela Banks crustacean and linefish fisheries and investigates the potential impacts of reduced flow from the Thukela River on the value of these fisheries. Data were obtained from published and unpublished material, key informants and government records. The crustacean fishery employs about 300 people, and comprises an inshore and offshore fishery. Inshore catches and effort are strongly seasonal, peaking in April to June. The probability of fishing in any particular month is positively correlated with catch per unit effort. Average overall annual catch (inshore and offshore) was estimated to be in the region of 700 tonnes for 1992–2002 with a gross output of about R36.7 million per annum, and a gross value added (net output) of R13.8 million (1 US$ = R6.40; 2003). Inshore prawns were estimated to contribute R8.5 million of the gross output. The Thukela Banks was estimated to contribute R4.5 million and R35 million (rand value in 2003) to the gross output of the commercial linefishery and boat-based recreational angling fishery respectively. Freshwater reduction scenarios yielded 0.7–11% reductions in prawn catches, which translated into only a 1–2% drop in the annual value of the fishery. The latter was attributed to the fishery’s diversity (predominantly the buffering effect of bycatch) and the fact that the stocks of the species targeted by the offshore component are largely independent of flow. Catches and value of the recreational boat-based linefishery were predicted to remain fairly constant irrespective of any changes in flow. The commercial linefishery was the most  responsive, with a 20% decline in total catch and 17% value predicted for the most extreme flow reduction scenario.

Keywords: catch flow relationships, economic implications, marine freshwater flow requirements, multispecies fisheries

African Journal of Marine Science 2010, 32(3): 613–624

Author Biographies

JK Turpie
Anchor Environmental Consultants, 8 Steenberg House, Silverwood Close, Tokai 7945, South Africa
SJ Lamberth
Branch Fisheries, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, South Africa; South African Institute for Aquatic Biodiversity (SAIAB), Private Bag 1015, Grahamstown 6140, South Africa
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Articles

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eISSN: 1814-2338
print ISSN: 1814-232X