A Preliminary Analysis of Freshwater Mussel Population Dynamics in Texas

Abstract

Freshwater mussels are among the most widespread riverine fauna in North America, constituting 50% or more of benthic biomass, but also one of the most imperiled. Although most of the 300 species in North American are poorly characterized, estimates of population parameters and detection probabilities from existing studies can be used to design monitoring programs that balance effort and statistical rigor. We used existing estimates of survival and detection probabilities within a simulation framework to assess minimum monitoring design requirements (numbers of sites and individuals) for analyzing freshwater mussel populations using mark-recapture methods. The simulations indicated that both the number of individuals available, and number of sampling occasions had potential to affect accuracy and precision of resultant estimates. Accuracy of survival estimates generally increased with increasing number of individuals until about 300 individuals and likewise increased with increasing number of sampling occasions until error was minimized at about 30 occasions. Precision similarly increased until a minimum of 250 individuals or 50 occasions. Future simulations will incorporate additional complexities and help guide management and research efforts. This will include exploration of robust design approaches incorporating both primary and secondary (replicate) sampling events for better estimation within shorter time frames.