Mortality, Predation, and Tag Visibility of Fish Marked with Visible Implant Elastomer Tags

We evaluated tag‐induced mortality (7 d), predation, and tag visibility (365 d) for age‐0 largemouth bass (LMB) Micropterus salmoides (27–112 mm total length [TL]), age‐0 channel catfish (CCF) Ictalurus punctatus (42–101 mm TL), and adult blacktail shiners (BTS) Cyprinella venusta (34–98 mm TL) tagged with three visible implant elastomer (VIE) tags. Tagging mortality after 7 d was 14.7% for age‐0 LMB and 29.5% for BTS, whereas there was almost no mortality for CCF. Mortality for tagged age‐0 LMB and BTS was size dependent; the smallest size‐groups exhibited the greatest mortality rates. Visible implant elastomer tags did not significantly increase predation of recently tagged fish by adult LMB, flathead catfish Pylodictis olivaris, or white bass Morone chrysops. Tag visibility (which reflects tag shedding and loss of visibility due to tissue thickening over the tag) varied greatly by species and tag location. In LMB, tag visibility decreased to 5% or less within 90 d for VIE tags in the dorsal head area and along the base of the anal fin, whereas visibility decreased gradually to 63% after 365 d for tags in the operculum. In CCF, tag visibility decreased to 5% or less within 90 d for tags in the dorsal head area and along the jaw, whereas visibility decreased to 46% after 365 d for tags along the base of the anal fin. Tags in BTS had the highest visibility: 100% visibility was recorded at all three tagging locations after 30 d, then visibility gradually decreased to 56% along the base of the anal fin, 72% in the dorsal portion of the caudal peduncle, and 78% in the ventral portion of the caudal peduncle after 365 d. Visible implant elastomer tags can be used without increasing risk of predation for tagged fish; however, VIE tag utility may be limited due to increased mortality for small age‐0 fish and variable tag visibility among anatomical locations.