An Evaluation of Sedatives for Use in Transport of Juvenile Endangered Fishes in Plastic Bags

Trucks and aircraft typically transport rare or endangered fishes in large unsealed tanks containing large volumes of water (typically hundreds of liters) during conservation efforts. However, to reduce weight and overall shipping costs, fish breeders commonly send ornamental fishes by mail in small sealed plastic bags filled with oxygen, minimal water, and a small amount of sedative. Our goal was to evaluate if we could also use these “minimal-water” methods used for shipping ornamental fishes to safely transport endangered Humpback Chub Gila cypha into remote locations within Grand Canyon on foot to eliminate helicopter transportation costs associated with conservation actions. In the laboratory, we placed 20 (mean = 193.9 g of fish/L, SD = 37.8) juvenile Bonytail Gila elegans or Humpback Chub in plastic bags containing 1 L of water and pure oxygen for 4, 8, and 12 h. Treatments contained either no sedative or one of three sedatives—AquaCalm (metomidate hydrochloride), Tricaine-S (tricaine methanesulfonate or MS-222), or Aqui-S 20E (eugenol)—to evaluate the effectiveness of minimal-water methods for use in fish transport. Aqui-S 20E and the control without sedatives exhibited the highest survival (logistic regression, Aqui-S 20E, p = 0.994, 95% CI [0.978, 0.998]; control, p = 0.995, 95% CI [0.981, 0.998]), followed by Tricaine-S (p = 0.933, 95% CI [0.902, 0.955]) and AquaCalm (p = 0.355, 95% CI [0.307, 0.406]). We also conducted a field trial in which we placed 240 juvenile Humpback Chub in shipping bags (n = 20 fish/bag/L of water; mean = 143.2 g of fish/L, SD = 9.72) with no sedative or 10.0 mg/L of Aqui-S 20E and transported them by vehicle and on foot. No fish perished during transport, indicating fisheries personnel can use these minimal-water methods to safely, and at little expense, transport endangered Humpback Chub into remote locations.