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Revisiting Beverton–Holt recruitment in the presence of variation in food availability

Authors
  • van Poorten, Brett1, 2
  • Korman, Josh3
  • Walters, Carl2
  • 1 British Columbia Ministry of Environment and Climate Change Strategy, 2202 Main Mall, Vancouver, Canada , Vancouver (Canada)
  • 2 Institute for the Oceans and Fisheries, 2202 Main Mall, Vancouver, Canada , Vancouver (Canada)
  • 3 Ecometric Research Inc, 3560 W 22nd Ave., Vancouver, Canada , Vancouver (Canada)
Type
Published Article
Journal
Reviews in Fish Biology and Fisheries
Publisher
Springer-Verlag
Publication Date
Jun 02, 2018
Volume
28
Issue
3
Pages
607–624
Identifiers
DOI: 10.1007/s11160-018-9521-6
Source
Springer Nature
Keywords
License
Yellow

Abstract

Understanding density-dependent changes in juvenile survival and growth rates is of great importance because these rates determine recovery rates for imperiled populations and/or sustainable harvest rates. Unfortunately, the mechanisms leading to density dependent survival and growth are among the least understood process in biology and fisheries. Previous work has shown that small fish may vary foraging times to achieve a target growth rate, resulting in the well-known Beverton–Holt recruitment function with variation in food availability affected the initial slope of the recruitment curve. We amend their derivation to show that incorporating fish growth under a variety of evolutionary strategies for balancing foraging time and predation risk still leads to recruitment approximately as expected under the Beverton–Holt recruitment model but that changing food availability affects both the initial slope and maximum recruitment level. We demonstrate that when food availability is known to vary over time, these models often result in a more parsimonious alternative than the standard Beverton–Holt function. Further, Beverton–Holt recruitment is expected when foraging times are adjusted to balance fitness gains from growth against mortality risk. Finally, linking recruitment success to food availability warns that species with high scope for density dependent survival (high compensation ratio or steepness) may be extremely sensitive to changes in available food densities. This work emphasizes the sensitivity of stock-recruitment parameters to food availability and strongly suggests a need to carefully monitor lower trophic levels to better understand and predict dramatic changes in juvenile recruitment and carrying capacity.

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