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. Ornamental fishes, however, are commonly sent by mail in small sealed plastic bags filled with oxygen, minimal water, and a small amount of sedative to reduce weight and overall shipping costs. Our goal was to evaluate if these "minimal water" methods used for shipping ornamental fishes could also be used 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, 20 (mean, M = 193.9 g of fish/L, SD = 37.8) juvenile Bonytail, Gila elegans, or Humpback Chub were placed in plastic bags containing 1 liter of water and pure oxygen for 4, 8, and 12 hours. 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/1L of water; M = 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 these minimal water methods can be used to safely, and at little expense, transport endangered Humpback Chub into remote locations.