Abstract

Queen conch (Lobatus gigas) are harvested intensively throughout the Caribbean for their meat, shell, and pearls. To ensure sustainability, fishery management strategies need to consider the distinctive biology of the species (e.g. density-dependent reproduction, determinate growth). In this vein, it is unknown if fecundity is influenced by size and age as in fish and lobster. Therefore, managers need to know if fecundity declines with age (i.e. thicker lips), and if so, does compensation occur by increasing mating and spawning frequency. We tracked 22 female conch at Looe Key, Flori-da and collected all egg masses laid from June to August 2011. Conch were grouped into age classes based on lip thickness: young adult 11 - 15 mm, adult 15 - 25 mm, very old > 25 mm. Female fecundity (i.e. the estimated number of eggs in an egg mass) showed no significant difference among age groups. However, transect surveys of spawning aggregations throughout the Florida Keys from 2003 - 2011 showed that young adults did not mate or spawn as frequently as adults and very old adults (p < 0.001). So while age does not seem to affect an individual’s fecundity, young adults as a group have lower reproductive output because they do not engage in reproductive activities as frequently as older individuals. As such, population demographics play a crucial role in recovery and/or sustainable harvest. This argues for incorporating management approaches that maximize reproductive output from mature aggregations whose densities exceed minimum thresholds to avoid Allee effects.

PDF Preview