Investigating the trophic ecologies of early life stages of small pelagic fishes in the Benguela upwelling ecosystem
type: CreativeWork
description: The Benguela upwelling system, located on the west coast of southern Africa, harbours large biomasses of three small pelagic fishes; anchovy Engraulis encrasicolus, sardine Sardinops sagax and west coast round herring Etrumeus whiteheadi. Despite fisheries management interventions, stocks of sardine have been low for the past decade following consecutive years of poor recruitment. This has highlighted that despite low fishing mortality, variance in recruitment may be largely governed by fluctuations in early-stage mortality rates. Therefore, examining early life traits that may explain a fraction of this mortality could be fundamental to understanding the underlying mechanics of recruitment. This study seeks to investigate the ontogenetic development in morphology and trophic ecology of early life stages of these three small pelagic fish species in the Benguela, and how they compare interspecifically and spatially. Increasing our temporal resolution of the ecological ontogeny of a species will enable accurate future analysis of trophic pathways and linkages within ecosystems and their feedback to vital ecosystem services such as fisheries. Results show that there is a high likelihood of trophic partitioning between sardine and anchovy larvae through distinct differences in their ecomorphology. Sardines exhibit traits in their development such as increased relative gut length, that would suggest a higher degree of herbivory compared to anchovy. Contrastingly, anchovy display positive allometric growth patterns in their cranial development at a younger age, suggesting a greater importance of particulate feeding on larger prey. These results provide an anatomical basis of how both the feeding ability and behaviour of these two species may differ which would predispose them to distinct diets. Both species exhibited trophic progression inferred through (a) a 15N enrichment and (b) an increase in carnivory fatty acid trophic markers. Interspecific partitioning is facilita…
abstract: The Benguela upwelling system, located on the west coast of southern Africa, harbours large biomasses of three small pelagic fishes; anchovy Engraulis encrasicolus, sardine Sardinops sagax and west coast round herring Etrumeus whiteheadi. Despite fisheries management interventions, stocks of sardine have been low for the past decade following consecutive years of poor recruitment. This has highlighted that despite low fishing mortality, variance in recruitment may be largely governed by fluctuations in early-stage mortality rates. Therefore, examining early life traits that may explain a fraction of this mortality could be fundamental to understanding the underlying mechanics of recruitment. This study seeks to investigate the ontogenetic development in morphology and trophic ecology of early life stages of these three small pelagic fish species in the Benguela, and how they compare interspecifically and spatially. Increasing our temporal resolution of the ecological ontogeny of a species will enable accurate future analysis of trophic pathways and linkages within ecosystems and their feedback to vital ecosystem services such as fisheries. Results show that there is a high likelihood of trophic partitioning between sardine and anchovy larvae through distinct differences in their ecomorphology. Sardines exhibit traits in their development such as increased relative gut length, that would suggest a higher degree of herbivory compared to anchovy. Contrastingly, anchovy display positive allometric growth patterns in their cranial development at a younger age, suggesting a greater importance of particulate feeding on larger prey. These results provide an anatomical basis of how both the feeding ability and behaviour of these two species may differ which would predispose them to distinct diets. Both species exhibited trophic progression inferred through (a) a 15N enrichment and (b) an increase in carnivory fatty acid trophic markers. Interspecific partitioning is facilita…
author: Horton, Matthew
keywords: Biological Sciences
date published: 2024
date modified: 2026-07-22T22:22:57Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Biological Sciences

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/40275