An alternative method for estimating the status of resident reef fish stocks, based on differential fishing effort across a marine reserve boundary

  • A Götz
  • SE Kerwath
  • CG Attwood
  • WHH Sauer

Abstract

The stock status of roman Chrysoblephus laticeps was estimated in the Goukamma, a temperate South African marine protected area (MPA). Standardised catch per unit effort (CPUE) from a controlled angling survey on both sides of the MPA border was employed to extrapolate the CPUE at zero fishing mortality. Converted into biomass, the estimate (61% of unexploited biomass) lay midway between those of two biomass-per-recruit (B/R) models for the same population based on angling and diving surveys (i.e. 52% and 69% of unexploited biomass respectively). The extrapolated CPUE at zero fishing mortality (4.4 fish angler-hour–1) in this study compared well with the mean CPUE of 4.6 fish angler-hour–1 determined during a concomitant survey in the core area of the nearby Tsitsikamma MPA — the oldest, and one of the largest, MPAs in Africa. Extrapolations of CPUE have the potential to deliver reliable and consistent estimates of stock status and could offer a practical alternative to conventional B/R models.

Keywords: biomass-per-recruit models, Chrysoblephus laticeps, CPUE extrapolation, fisheries management, marine protected area, stock status

African Journal of Marine Science 2011, 33(1): 107–113

Author Biographies

A Götz
Elwandle Node, South African Environmental Observation Network (SAEON), Private Bag 1015, Grahamstown 6140, South Africa
SE Kerwath
Branch Fisheries, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, South Africa
CG Attwood
Marine Research Institute, Zoology Department, University of Cape Town, Private Bag Rondebosch 7700, South Africa
WHH Sauer
Department of Ichthyology and Fisheries Science, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
Section
Articles

Journal Identifiers


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