Evaluating the viability of the use of T‐bar and radiotelemetry tags on prespawn Arctic Lampreys

Abstract Objective Arctic Lampreys Lethenteron camtschaticum are harvested by subsistence and commercial fisheries in the Yukon–Kuskokwim River region of Alaska; however, baseline population data are deficient. For mark–recapture and telemetry studies to be effectively implemented to assess Arctic Lamprey abundance, migratory and dispersal patterns, and spawning locations, tags must not impact fish survival, physiology, or behavior. Methods For this laboratory evaluation, we examined survival, tag retention, swim endurance at short‐term (1 day posttreatment) and long‐term (43 days [~6 weeks] posttreatment) intervals, and incision healing for T‐bar‐tagged and radio‐tagged prespawn Yukon River Arctic Lampreys ( N = 216). Six treatment groups were evaluated: control; sham surgery; external T‐bar anchor tag; and small (0.30 g; 0.1–0.4% tag burden [ratio of tag weight to fish body weight]), medium (0.57 g; 0.2–0.8% tag burden), and large (1.50 g; 0.6–1.9% tag burden) internal dummy radio transmitter tags. Result Although all lampreys survived tagging and surgical procedures through the first 4 weeks of the experiment, a higher tag burden was associated with an increased mortality hazard up to 35 weeks postsurgery. Over the 14‐week experimental period, one T‐bar tag and one small radio tag were shed by lampreys. Although treatment was not a significant predictor of swim endurance, a higher tag burden led to reductions in swim endurance at 1 day posttreatment but not at 43 days posttreatment. Healing did not differ among surgical treatment groups, but persistent inflammation was observed at incision sites and skin erosion was observed at antenna protrusion locations. Conclusion These results indicate that T‐bar anchor tags and internal radio tags are acceptable for Arctic Lamprey tagging studies if the radio tag burden is ≤1.3% for short‐term (≤14‐week) studies and ≤0.5% for long‐term (≥14‐week) studies.