Individual-based movement behaviour in a simple marine reserve-fishery system: why predictive models should be handled with care
Authored by Edward A Codling
Date Published: 2008
DOI: 10.1007/s10750-008-9345-9
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Abstract
The problem of overexploitation and unsustainability is a major issue in
global fisheries. Marine reserves or protected no-take zones have been
suggested as a possible solution that would maintain yield and protect
stocks indefinitely. A key factor in the effectiveness of a marine
reserve-fishery system is the rate of exchange of biomass between
reserve and fishery: if the rate of exchange is too low then the fishery
is not viable, but if the rate of exchange is too high then stocks may
be exploited unsustainably and the reserve is rendered ineffective. The
rate of exchange is determined by both the physical design and shape of
the reserve, and the movement and dispersal behaviour of both the adult
and larval-stage fish. Previous models looking at optimal reserve design
usually only consider a diffusive population scale movement and
dispersal, even though most animal movement is more realistically
modelled as being correlated at the individual level. In this article, a
deliberately simple simulation of a theoretical marine reserve-fishery
system is used to demonstrate the danger of making predictions using
only a population-level simplistic diffusive movement model. Further
predictions based on the population average of a more realistic
correlated movement model are also shown to be inaccurate. This result
is due to both the high levels of individual variability in movement
behaviour, and the heterogeneity of the environment. This suggests that
in future studies, individual-based (rather than population-level)
simulations and models are likely to give more useful insights into the
dynamics of the marine fishery environment.
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Recruitment