Temporal and spatial estimates of adult striped bass mortality from telemetry and transmitter return data

Estimates of total mortality, fishing mortality, and natural mortality in the fishery for the adult striped bass Morone saxatilis in J. Strom Thurmond Reservoir, South Carolina-Georgia, were determined from long-term radiotelemetry data and high-reward radio transmitter return data using catch curve analyses. Annual total mortality rates were 0.81 ?? 0.06 (mean ?? SE) for year 1 (July 1999-June 2000) and 0.42 ?? 0.04 for year 2 (July 2000-June 2001). We observed that the force of fishing was much greater than the force of natural death on total mortality in this fishery. Total exploitation of all implanted striped bass over the 2-year study period was 48%. Fishing mortality rates were 0.67 ?? 0.04 for year 1 and 0.33 ?? 0.02 for year 2, and natural mortality rates were 0.14 ?? 0.02 for year 1 and 0.09 ?? 0.02 for year 2. We also identified seasonal increases in total and fishing mortality rates from July to September. Fishing mortality was highest temporally and spatially during late spring and late summer near the tailrace below Richard B. Russell Dam owing to high angling pressure for striped bass while the fish were congregated in summer refugia. Natural mortality occurred only during mid to late summer in the middle section of the reservoir. These deaths were attributed to striped bass's becoming trapped in unsuitable summer habitat in the lower and middle sections of the reservoir. Mean postsurgery growth from 15 harvested study fish at large for a mean of 1.16 ?? 0.81 years was estimated to be 1.71 ?? 0.73 kg/year. Internal implantation of telemetry devices appeared to have no negative effect on long-term growth, health, and survival of adult striped bass and did not bias mortality and survival estimates.