Evaluation of tag types and adhesives for marking freshwater mussels (Mollusca : Unionidae)

Prior to initiating a long-term tagging program on freshwater mussels, we e valuated three varieties of tags (Northwest Marine Technology Visual Implan t Tag, Floy Fingerling Tag, and Hallprint Shellfish Tag) two types of adhes ives (3M two-parr epoxy and Krazy Glue cyanoacrylate), and four bonding tim es before immersion in water (2, 5, 10, and 15 min). Tags were applied to e mpty shells for two phases of testing. First, legibility was visually score d for each of the immersion times. The two-part epoxy became cloudy at imme rsion times < 15 min, was easily abraded after curing, and was, therefore, eliminated from further testing. The visual implant tag also was eliminated from further testing because the printing dissolved in the cyanoacrylate. In the second phase, the fingerling tag and the shellfish lag bonded with c yanoacrylate were tested for durability and retention under natural conditi ons in a shallow stream and under highly abrasive conditions in a standard gem tumbler containing coarse metal shavings. Tag losses after 16 wk in the instream test were 5.3% for the shellfish tag and 2.6% for the fingerling tag. These tests revealed no loss of legibility after the removal of materi al that accumulated on the tag surface. There was no appreciable wear of ei ther tag type after 1 wk in the gem tumbler. Flexible polyethylene shellfis h tags were chosen for field application because they are thinner and avail able with a larger number of individual codes than fingerling tags. Tags bo nded to the shells of live mussels with cyanoacrylate can be immersed in wa ter in as little as 2 min after application without affecting retention. Th is method was used to double-tag 1,372 mussels at a monitoring site on the Cacapon River in West Virginia. After 2 y, the total rag loss in 325 recove red mussels was 0.46%.