Can Unionid Mortality Be Estimated From Dead Shells? A Simulation Study

Environmentally persistent structures of dead individuals represent an unexplored avenue to estimate some population parameters for endangered species that cannot sustain lethal sampling. We used simulations to explore the feasibility of applying catch-curve analysis from dead unionid shells to estimate mortality. We found that when shell persistence was nonconstant across age-classes, weighted regressions produced biassed results. Chapman–Robson estimates, however, were more robust with performance comparable to estimates from catch-curve analysis on live individuals. Application of Chapman–Robson catch curve analysis to dead unionid shells represents a simple, cost-effective and nonlethal approach to increase our understanding of unionid life history.