Evaluation of Sprayed Fluorescent Pigment as a Method to Mass-Mark Fish Species

A technique for mass-marking fish was evaluated that forces fluorescent pigment into dermal tissue with compressed air. A five month trial was conducted where mark retention, readability, and marking mortality were evaluated with six fish species that represent a variety of taxonomic groups. Approximately 100 of each species were marked; a percentage with fluorescent sprayed pigment and visible implanted elastomer (VIE) and the remaining with bilaterally distinct VIE tags. Marking mortality ranged from 0 to 100 percent and for three species mortality was size dependent. Mark retention declined at different rates for each species and ranged from 6 to 65 percent after five months. False-positive values and imperfect mark detection on poorly marked individuals affected retention. Growth of marked fish compared to unmarked control groups was significantly lower for two species. Because of inconsistency within and among species, fluorescent spray procedures need refinement and additional assessment prior to fisheries application.