Retention of passive integrated transponder tags in age-0 Lake Sturgeon and effects on growth and survival

Objective Passive integrated transponder (PIT) tags are used in fisheries studies to estimate population ­demographics, track movement, and assess stocking programs. Retention of PIT tags is dependent upon tag size and location, emphasizing the need for species- and size-specific retention studies to understand tagging limitations and implications to mark–recapture data. Implanted tags generally have high retention rates and minimal ­effects on large-bodied fish, while larger tags in small-bodied fish may result in negative side effects (slower growth, high posttagging mortality). Additionally, there is often a trade-off between tag retention and detection with different tag sizes (i.e., decrease in tag size results in decrease in tag detection). Therefore, the objective of this study was to determine if fish length, PIT tag size (8 mm or 12 mm), and/or tagging additive (i.e., n-­butyl-cyanoacrylate surgical adhesive at the tag insertion point) influences tag retention, growth, and survival of age-0 Lake Sturgeon Acipenser fulvescens. Methods We implanted 293 fish ranging from 75 to 205 mm total length (TL) with 8- and 12-mm PIT tags, with half the fish from each treatment group receiving n-BCA surgical adhesive at the tag insertion point. To determine if growth was influenced by treatment group, TL and weight were compared between the beginning and end of the study. Tag loss was monitored daily in a controlled hatchery environment for 84 to 98 d after tagging. Results Tag retention increased as TL increased and was lower in the 12-mm n-­butyl-cyanoacrylate treatment group when compared with all other treatments. Tag loss was greatest within 14 d posttagging, but fish continued to lose tags up to 63 d after tagging. No growth differences were observed between treatment and control groups. Retention of 8-mm PIT tags was greater than 12-mm tags; however, 100% retention was observed in fish >175 mm TL, irrespective of tag size. Conclusions When possible, we suggest implanting age-0 Lake Sturgeon with larger PIT tags at a size >175 mm TL to increase retention and detection rates. Lastly, holding fish up to 14 d after tagging could reduce poststocking tag loss and better inform future stocking program evaluations.