Vital dye immersion evaluations with juvenile delta smelt

Abstract Immersion‐based vital dyes were tested as a marking method for use in larval smelt mark–recapture studies. We assessed five fluorescent mark juvenile osmerids: 4‐Di‐1‐ASP, BODIPY FL C12, 505/515, Nile red, and calcein. marked Delta Smelt, Hypomesus transpacificus , proxy Longfin Spirinchus thaleichthys to determine the efficacy of each batch technique osmerids based on dye performance survival. All groups Smelt including control exhibited high mortality (71%–100%, 5 days after trial), lowest survival was observed 4‐Di‐1‐ASP‐treated fish. Highest red‐ C12‐treated Fluorescence observations indicated that brightest, visible fluorescence seen calcein lesser extent, followed by C12 red. In addition performance, it is recommended immersion techniques improve be considered.