Modeling the Effects of Commercial Harvest on Population Growth of River Turtles

Abstract

Abstract Commercial turtle harvest is considered one of the major contributing factors to declines in turtle populations. Few long-term studies have evaluated turtle population response to harvest and little is known about demographic rates for many turtle species. We gathered demographic rates from the literature for snapping turtles (Chelydra serpentina), smooth softshells (Apalone mutica), and spiny softshells (Apalone spinifera), which are harvested in Missouri, and developed deterministic, density-independent, stage-based matrix models to assess turtle population response to plausible harvest rates we estimated from field sampling. Further, we used population modeling to determine annual harvest rates that would result in λ = 1 for each demographic scenario. We developed one model for snapping turtles and another for both softshell species combined due to the lack of available species-specific demographic data for either softshell species. Using mean demographic rates for survival and fecundity, sn...