Merluccius capensis spawn in Namibian waters, but do M. paradoxus?

Paulus Inekela Kainge, O. S. Kjesbu, A. Thorsen, A. G. Salvanes

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Spawning time and areas, and the length of the spawning season of shallow-water (Merluccius capensis) and deep-water (M. paradoxus) hake, were investigated from bottom trawl collections taken in Namibian waters between September 1998 and October 2000 and from August to November 2001. The gonadosomatic index (GSI) and the incidence of advanced maturity stages of M. paradoxus were low along the entire coast throughout the year, but with a few exceptions in the south (between Luderitz and Orange River). By contrast, M. capensis spawn in the area throughout the year, but mainly between July and October. Evaluating the accuracy of visual maturity staging by comparing results with those of image and histological analyses revealed few errors in classifications of maturity stage in the field, with the exception of Stage 5 (spent and resting) in M. paradoxus. Specific GSI values were intercalibrated with the appearance of developing oocytes. As the GSI is quickly estimated, this new concept, designated here as a 'maturity reference line', could enhance understanding of the spawning biology of other species with a similarly complex, indeterminate spawning strategy. It is concluded that M. paradoxus do not appear to spawn in Namibian waters.
Original languageEnglish
JournalAfrican Journal of Marine Science
Volume29
Issue number3
Pages (from-to)379-392
ISSN1814-232X
DOIs
Publication statusPublished - 2007
Externally publishedYes

Keywords

  • Aquatic Science
  • GSI
  • Hake
  • Image analysis
  • Maturity staging
  • Namibia
  • Spawning time
  • Coastal zones
  • Error analysis
  • Fish
  • Water analysis
  • bottom trawling
  • comparative study
  • gadoid
  • histology
  • image analysis
  • sexual maturity
  • spawning population
  • Africa
  • Southern Africa
  • Sub-Saharan Africa
  • Merluccius capensis
  • Rexea solandri
  • MARINE
  • COD GADUS-MORHUA
  • HERRING CLUPEA-HARENGUS
  • BATCH FECUNDITY
  • OVARIAN DEVELOPMENT
  • OOCYTE DIAMETER
  • EGG-PRODUCTION
  • ATLANTIC
  • MATURITY
  • BISCAY
  • FISH
  • hake
  • maturity staging
  • spawning time
  • Namibia Africa Ethiopian region
  • gonadosomatic index
  • maturity reference line
  • spawning
  • visual maturity
  • Pisces Vertebrata Chordata Animalia (Animals, Chordates, Fish, Nonhuman Vertebrates, Vertebrates) - Osteichthyes [85206] Merluccius capensis species Merluccius paradoxus species
  • 02506, Cytology - Animal
  • 07502, Ecology: environmental biology - General and methods
  • 07508, Ecology: environmental biology - Animal
  • 07512, Ecology: environmental biology - Oceanography
  • 16504, Reproductive system - Physiology and biochemistry
  • 62800, Animal distribution
  • Ecology, Environmental Sciences
  • Population Studies
  • oocyte reproductive system
  • Biogeography
  • Marine Ecology
  • Reproduction

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