Retention of T-Bar Anchor Tags and Passive Integrated Transponder Tags by Gulf Sturgeons

Abstract

One thousand nine-hundred and four Gulf sturgeons Acipenser oxyrinchus desotoi were marked and returned to the Suwannee River, Florida, between March 1988 and November 1993 as part of life history and population dynamics studies, This Atlantic sturgeon A. oxyrinchus subspecies is federally listed as threatened, A T-bar anchor tag was placed into both pectoral fins, and a passive integrated transponder (PIT) tag was injected near the base of the dorsal fin of each fish to enhance the expected recovery rate and to provide a means of estimating tag retention. Relative tag retention was estimated from the ratio of recaptured fish with a specific tag to the total number of tagged fish recaptured. Relative tag retention was 89.3–94.9% for both types of tags during the first year at large. However, during the latter years of the study, retention for anchor tags declined in most cases to about 60%, while PIT tag retention remained near 90% throughout the evaluation. Both tags were retained at levels useful for many types of tagging studies, For sturgeon studies that are intended to last only a few years, anchor tags attached to the pectoral fins may be the most economical choice, Following a low initial rate of loss, PIT tags are probably retained for the life of the fish and thus are recommended for long-term studies.