Stock-environment recruitment analysis for Namibian Cape hake Merluccius capensis

Paulus Inekela Kainge, N. Bahamon, C. H. Bartholomae, Johannes N. Kathena, A. K. van der Plas, A. Gordoa

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The factors modulating recruitment success of Cape hake Merluccius capensis in Namibian waters are still unresolved. In this study, we used generalised additive models, regression tree analysis and the conventional Ricker model to examine the effect of environmental indices and spawning stock biomass (SSB) on hake recruitment success for the period 1984-2012. Results indicated that upwelling strength explained 51% of the recruitment variability, whereas SSB had no significant influence. The effect of SSB on recruitment only became significant when combined with upwelling strength, explaining 89% of the recruitment variability. SSB influenced recruitment during periods of strong upwelling. Optimal conditions for hake recruitment were associated with moderate upwelling strength. Low and high upwelling intensities reduced recruitment success. Our results are consistent with those of other studies suggesting a significant influence of environmental conditions on recruitment at a low spawning stock level. Our study highlights the importance of assessing the combined non-linear effects of both biotic and abiotic factors on hake recruitment.
Original languageEnglish
JournalAfrican Journal of Marine Science
Volume35
Issue number4
Pages (from-to)555-564
ISSN1814-232X
DOIs
Publication statusPublished - 2013
Externally publishedYes

Keywords

  • Aquatic Science
  • Ecology, Evolution, Behavior and Systematics
  • generalised additive models
  • sea surface temperature
  • spawning-stock biomass
  • upwelling indices
  • biomass
  • environmental conditions
  • environmental factor
  • gadoid
  • recruitment (population dynamics)
  • spawning
  • temporal analysis
  • upwelling
  • Namibia
  • MARINE
  • BENGUELA UPWELLING REGION
  • EARLY LIFE-HISTORY
  • COD GADUS-MORHUA
  • NORTHERN BENGUELA
  • FISH RECRUITMENT
  • FISHERIES MANAGEMENT
  • TRAWL FISHERY
  • LARGE-SCALE
  • BIOMASS
  • ECOSYSTEM
  • Namibia Africa Ethiopian region
  • abiotic factor
  • biotic factor
  • environmental index effect
  • spawning stock biomass
  • species recruitment success
  • upwelling strength
  • Pisces Vertebrata Chordata Animalia (Animals, Chordates, Fish, Nonhuman Vertebrates, Vertebrates) - Osteichthyes [85206] Merluccius capensis species cape hake common mature, immature protected species
  • 00512, General biology - Conservation and resource management
  • 04500, Mathematical biology and statistical methods
  • 07502, Ecology: environmental biology - General and methods
  • 07508, Ecology: environmental biology - Animal
  • 07512, Ecology: environmental biology - Oceanography
  • 07516, Ecology: environmental biology - Wildlife management: aquatic
  • 10515, Biophysics - Biocybernetics
  • Computational Biology
  • Conservation
  • Ecology, Environmental Sciences
  • generalized additive model mathematical and computer techniques
  • Holt stock-recruitment model mathematical and computer techniques
  • regression tree analysis mathematical and computer techniques
  • Ricker and Beverton stock-recruitment model mathematical and computer techniques
  • Marine Ecology
  • Models and Simulations
  • Wildlife Management
  • MARINE ecology

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