Application of the extractable lipofuscin aging method to estimate mortality and population dynamics of the burrowing shrimp, Neotrypaea californiensis

Abstract

Lack of robust aging methods for crustaceans has inhibited the use of age-structured population models. Individuals are often classified based on body size, but differences in growth can bias parameter estimates. Our study applied the lipofuscin aging method combined with catch-curve analysis to estimate mortality rate for the burrowing shrimp, Neotrypaea californiensis. This species is an important member of the estuarine community with an impact on oyster production along the US West Coast. Randomized surveys were conducted from 2011 to 2014 to estimate population abundance, average density, and age structure in Yaquina Bay, Oregon. Mortality rate was estimated to be 0.719 yr−1 (95% CI; 0.633–0.793 yr−1) and did not vary significantly across cohorts. The spatial extent of the survey revealed spatial patterns in shrimp density that could be explained by variation in mortality and recruitment rates. This is the first study to apply lipofuscin aging to estimate population parameters of an estuarine crustacean and the methods we present can inform managers seeking to incorporate population ecology into management plans for N. californiensis and other crustacean species worldwide.