USE OF SALTS, ANESTHETICS, AND POLYMERS TO MINIMIZE HANDLING AND TRANSPORT MORTALITY IN DELTA SMELT

We tested the effects of transport containers and transport, water tre atments on the survival of held-collected delta smelt Hypomesus transp acificus, ii threatened osmerid endemic to the Sacramento-San Joaquin estuary in California. Use of cylindrical polyethylene bags instead of rectangular coolers as transport containers increased survival from 4 0.7 to 83.68 at 4 h postcollection, from 11.9 to 33.1% at 48 h, and fr om 6.9 to 27.9% at 72 h. Addition of NovAqua, a commercial water condi tioner containing polymers, to transport water of 8 parts per thousand NaCl significantly increased 72-h survival(54.8%) over that of the 8 parts per thousand NaCl control (27.9%). Survival of fish lightly anes thetized with MS-222 (tricaine methanesulfonate) during transport was intermediate between the NaCl and NaCl plus NovAqua treatments. Surviv al of delta smelt in the NaCl plus NovAqua treatment also improved fro m August through November, as fish increased in size and water tempera ture decreased. Improved survival of delta smelt treated with NovAqua was probably related to the polymers, which may have reduced physiolog ical stress responses, such as osmotic imbalance.