Abstract

Queen conch are among the most economically, socially, and culturally important fishery resources in the Caribbean. Despite a multitude of fisheries management measures enacted across the region, populations are depleted and failing to recover. It is believed that queen conch are highly susceptible to depensatory processes, impacting reproductive success and contributing to the lack of recovery (Appeldoorn 1995). Empirical observations have suggested mating and egg laying in queen conch are directly related to the density of mature adults (Stoner and Ray-Culp 2000, Stoner et al. 2011, Stoner et al. 2012). In animals that aggregate, low population densities can make it difficult or impossible to find a mate, an issue which is likely compounded for slow-moving animals such as conch. Observations of queen conch populations also suggest an Allee effect, where little to no mating occurs below a critical density threshold (Stoner et al. 2011, Delgado and Glazer 2020). To test whether challenges in mate finding at low densities could explain mating frequency patterns observed in the field, male and female conch movements, mating (i.e., collisions), and spawning (i.e., egg laying) were simulated in R using package ‘particles’. The simulation assumes a constant unit time step Δt = 1 d for each step and a constant unit mass m = 1 for all particles (i.e., adult conch). As a result, a force F acting on a conch is equivalent to a constant acceleration a over the time interval Δt and can be simulated simply by adding to the conch’s velocity, which is then added to the conch’s position.

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