Spawning strategies and transport of early stages of the two Cape hake species, Merluccius paradoxus and M. capensis, in the southern Benguela upwelling system

  • B Grote
  • EK Stenevik
  • W Ekau
  • HM Verheye
  • MR Lipiński
  • W Hagen

Abstract

Seasonal and short-term variability of environmental parameters influence the spawning strategies of fish species. In this study, the spawning strategies and the transport of early stages of the two Cape hake species off South Africa were investigated. Distribution of eggs and larvae of Merluccius paradoxus and M. capensis was analysed in order to derive more detailed and species-specific information on spawning season, spawning location, and transport of early stages. Samples were collected during three pilot surveys between January and October 2007 and during an extensive survey in September/October 2008 in the southern Benguela upwelling system off South Africa. Eggs and larvae of M. paradoxus were found in greater numbers than those of M. capensis during all surveys. Highest abundances were found from September to October, indicating one spawning peak for M. paradoxus during late austral winter to spring. The western Agulhas Bank was identified as the primary spawning ground, and smaller spawning events occurred on the West Coast. Larvae of both species were mainly distributed in subsurface waters between 25 and 100 m. More than 50% of all larvae caught had a total length between 3 and 4 mm and size increased significantly with decreasing latitude. Merluccius capensis were found closer inshore than M. paradoxus, indicating that early stages of the two species followed separate drift routes. We assume that this distribution pattern most likely evolved from differences in spawning location and phenology. The spawning strategies of M. paradoxus and M. capensis are well adapted to a time-frame of optimal transport conditions favourable for larval survival in the highly variable environment of the southern Benguela upwelling system, but the peak spawning of the two species is separated in time and space.

Keywords: Benguela Current, drift pattern, early life history, spawning strategy

African Journal of Marine Science 2012, 34(2): 195–204

Author Biographies

B Grote
Leibniz Centre for Tropical Marine Ecology, Fahrenheitstrasse 6, 28359 Bremen, Germany; Marine Zoology, University of Bremen, Leobenerstrasse, PO Box 330440, 28359 Bremen, Germany
EK Stenevik
Institute of Marine Research, PO Box 1870, Nordnes, 5817 Bergen, Norway
W Ekau
Leibniz Centre for Tropical Marine Ecology, Fahrenheitstrasse 6, 28359 Bremen, Germany
HM Verheye
Oceans and Coasts Research, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7701, South Africa
MR Lipiński
Branch: Fisheries, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, South Africa
W Hagen
Marine Zoology, University of Bremen, Leobenerstrasse, PO Box 330440, 28359 Bremen, Germany
Section
Articles

Journal Identifiers


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