RESEARCH PAPER
Revisiting Beverton–Holt recruitment in the presence
of variation in food availability
Brett van Poorten
.
Josh Korman
.
Carl Walters
Received: 13 October 2017 / Accepted: 26 May 2018
Ó Springer International Publishing AG, part of Springer Nature 2018
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 recruit-
ment 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 chang-
ing 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 dra-
matic changes in juvenile recruitment and carrying
capacity.
Keywords Density-dependent Á Growth Á Juvenile
survival Á Predation Á Prey density Á Recruitment Á Risk
Introduction
During early life when fishes may be subject to
density-dependent mortality leading to stock recruit-
ment relationships like the Beverton–Holt, mortality
rates are likely to be high due to predation and to be
dependent on growth rates and/or time spent foraging,
both of which could be sensitive to food availability in
B. van Poorten (&)
British Columbia Ministry of Environment and Climate
Change Strategy, 2202 Main Mall, Vancouver, Canada
e-mail: Brett.vanPoorten@gov.bc.ca
B. van Poorten Á C. Walters
Institute for the Oceans and Fisheries, 2202 Main Mall,
Vancouver, Canada
J. Korman
Ecometric Research Inc, 3560 W 22nd Ave., Vancouver,
Canada
123
Rev Fish Biol Fisheries
https://doi.org/10.1007/s11160-018-9521-6
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