Evaluation of four methods of transmitter attachment on shortnose sturgeon, Acipenser brevirostrum

Two experiments were conducted to examine the retention and health effects of transmitter attachment on cultured shortnose sturgeon, Acipenser brevirostrum. Experiment 1 was a replicated study using a control group and three treatments. Treatments consisted of: (i) ventral implantation of a transmitter with internally coiled antenna, (ii) ventral implantation of a transmitter with an externally trailing antenna, and (iii) external attachment at the base of the dorsal fin of the transmitter used in treatment 2. Treatment 1 provided 100% survival and retention over the study period, and necropsies indicated there were no effects on internal organs. In treatment 2, all fish survived through day 93, but the antennae severely cut the body wall as the transmitters migrated posteriorly, leaving a long wound through which transmitters were lost ( and which later caused 100% mortality). In treatment 3, transmitter loss began on day 2, and all external transmitters but one had been shed by day 41 due to wire breakage caused by active rubbing of the fish against rocks in the tank. Ventral implantation of transmitters with internally coiled antennae provided the best results; their use is currently recommended for long term telemetry studies of shortnose sturgeon. Experiment 2 was a replicated 60-day study of juveniles designed to test an attachment method suitable for high temperature conditions ( i. e. no surgery; minimal handling) and small, short-lived transmitters. Transmitters were attached by heat-shrink plastic tubing to metal tipped dart tags, which were inserted just lateral to the anterior dorsal scutes. One treatment fish died during the first days due to improper ( too deep and anterior) tag insertion. There were no other mortalities or tag losses during the study. This attachment method is acceptable for studies using small transmitters during high temperature periods.