A combined telemetry – tag return approach to estimate fishing and natural mortality rates of an estuarine fish

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Bacheler, Nathan M., Buckel, Jeffrey A., Hightower, Joseph E., Paramore, Lee M., Pollock, Kenneth H.
• Other Authors: Jech, Josef Michael
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2009
• Subjects: Red drum; Sciaenops ocellatus
• Online Access: http://dx.doi.org/10.1139/f09-076; http://www.nrcresearchpress.com/doi/full-xml/10.1139/F09-076; http://www.nrcresearchpress.com/doi/pdf/10.1139/F09-076

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum ( Sciaenops ocellatus ) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry – tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ± standard error: 0.04 ± 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry – tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.