Assessment of the South African hake resource taking its two-species nature into account

  • RA Rademeyer MARAM (Marine Resource Assessment and Management Group), Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
  • DS Butterworth MARAM (Marine Resource Assessment and Management Group), Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
  • ÉE Plagányi MARAM (Marine Resource Assessment and Management Group), Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa

Abstract

The commercially valuable hake fishery off South Africa consists of two morphologically similar species, the shallow-water Cape hake Merluccius capensis and the deep-water Cape hake M. paradoxus. Because catch-andeffort statistics collected from the fishery are not species-disaggregated, previous published quantitative assessment methods have treated the two hake species as one. Furthermore, recent evidence suggests that (although treated as two separate populations in past assessments) the South and West coasts components of each species form a single stock. This paper describes the development of the first fully species-disaggregated coast-wide baseline assessment of the South African hake resource. M. paradoxus is estimated to be currently at <10% of its pre-exploitation level whereas M. capensis is estimated to be well above its maximum sustainable yield level. By taking into consideration the primary sources of uncertainty in this assessment, a Reference Set of 24 operating models is developed to be used in Operational Management Procedure testing.

Keywords: fisheries stock assessment; hake; multistocks; Reference Set; South Africa

African Journal of Marine Science 2008, 30(2): 263–290
Published
2008-10-20
Section
Articles

Journal Identifiers


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