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Master Thesis

A dynamic model of parrotfish (family: Scaridae) populations for the management of herbivory on Caribbean coral reefs

Abstract : A population model of the stoplight parrotfish (Sparisoma viride), an important herbivorous fish of Caribbean coral reefs, was developed to support the management of reef resilience. The model is in discrete-time and structured by size and habitat occupation, and simulates the abundance of S. viride as a function of natural mortality, individual growth, and recruitment. Habitat occupation for large fish is driven by density-dependence in deep reef habitats, as suggested by observations of a limited number of mature adults on deep reefs due to territoriality. The model was developed and calibrated with a time series of S. viride abundance in Bonaire (Southern Caribbean), a marine reserve, where the population is assumed to be at equilibrium. With parameter values derived from the literature, the model was able to reproduce the size distribution of the parrotfish population. Different mortality functions were tested, and optimisation results showed that a size-dependent mortality did not improve much the model fit compared to a constant mortality per size. With the calibrated model, we then explored the ability of the parrotfish population to recover from a depleted stock by simulating a fishing disturbance similar in proportion to that experienced by S. viride in Bermuda (Northern Caribbean) before a fishery ban was implemented. The calibrated model simulated a full recovery at a much lower speed (3 times slower) than observed in Bermuda. Among other assumptions, a much lower mortality of S. viride in Bermuda is suggested to explain this difference. Being the main herbivores on today Caribbean reefs, parrotfish are essential for the maintenance of corals face to global warming-induced disturbances. Thus, this preliminary model may become a useful tool for the exploration of fishing and conservation scenarios on herbivory and reef resilience in the Caribbean.
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Master Thesis
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Submitted on : Wednesday, November 20, 2013 - 2:33:53 PM
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  • HAL Id : dumas-00906910, version 1

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Caroline Baille. A dynamic model of parrotfish (family: Scaridae) populations for the management of herbivory on Caribbean coral reefs. Sciences agricoles. 2013. ⟨dumas-00906910⟩

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