Assessment of Freshwater Mussel Relocation as a Conservation Strategy

Over the last 30 years, relocation of freshwater mussels has been used as a conservation strategy for potential impacts from bridge construction and dredging operations. Improved methods have effectively increased relocated mussel survivorship rates of target species from ~ 50% to ~ 90% under ideal circumstances. Success to date is largely based upon survivorship rates without consideration of relocation activity effects upon fitness and behavioral traits of mussels. In 2003, the Federal Highway Administration (FHWA) and Arkansas Highway and Transportation Department (AHTD) funded research to: 1) determine the success of mussel relocation efforts associated with highway construction projects by investigating survivorship, movements, mortality, fitness (as indicated by condition factor), and fecundity of relocated and non-relocated adults and sub-adults, 2) determine success of mussel propagation efforts by investigating survivorship of juveniles returned to identified habitats and used for population enhancement (recruitment), and 3) determine impacts at highway construction sites by comparing pre- and post-construction mussel assemblage abundance and composition, sediment deposition downstream of the construction, and individual mussel fitness. This project seeks, in part, to use the data acquired in the formulation of a programmatic biological assessment/biological opinion streamlining initiative for P. capax that will be proposed to the U. S. Fish and Wildlife Service by the ATHD and FHWA. Biochemical composition (i.e. condition factor) and movement (i.e. displacement) were monitored for two species of freshwater mussels subjected to relocation activity, the federally endangered P. capax and a species with a different life history, Quadrula quadrula and compared with control (i.e. non relocated) populations. Trends were identified in condition factor, through repeated measures ANOVA, associated with short (glycogen), moderate (lipid), and long term energy stores (proteins, RNA:DNA ratios) sampled pre- and post-relocation. Behavioral trends (i.e. displacement) between native and relocated populations of the two species were measured in both short-term (weeks) and long-term (quarterly) intervals. Results pertaining to population enhancement strategies, specifically field methodologies used for in-situ rearing of juvenile P. capax along with growth and survival rates of field reared and lab reared individuals are presented.