The Effects of Aqui-S®20E (10% Eugenol) Sedation on Yellow Perch Perca flavescens and Talipia Oreochromis niloticus for Transport

Abstract

Fish transport costs are a substantial portion of the operational expenses of the aquaculture industry, especially as fuel costs continue to rise. Increasing fish loading density during transport could reduce expenses by enabling the transport of more fish mass per gallon of fuel. I hypothesized that the addition of AQUI-S®20E (10% eugenol, Lower Hutt, New Zealand), a eugenol based sedative, could allow increased loading densities without increasing mortality. In these studies, I used yellow perch Perca flavescens and Nile tilapia Oreochromis niloticus as model species to examine behavior, recovery from sedation, ammonia accumulation, eugenol uptake from water, survival and metabolic rates when exposed to AQUI-S®20E. AQUI-S®20E is a product currently being evaluated by the U.S. Food and Drug Administration Center for Veterinary Medicine as an immediate release finfish sedative. Fish were exposed to 0 to 300 mg L-1 AQUI-S®20E (0 to 30 mg L-1 eugenol) at loading densities up to three times the current industry standard during simulated transport and static respirometry. Concentrations of AQUI-S®20E ranging from 200 to 300 mg L-1 (20 to 30 mg L-1 eugenol) resulted in light sedation, >95% mean survival 7-day post-transport and decreased metabolic rates for yellow perch at loading densities up to 360 g L-1 (three times the industry standard) in 17°C water. Tilapia held at 22°C showed minimal changes in metabolic rate and sedation when exposed to AQUI-S®20E concentrations up to 300 mg L-1 (30 mg L-1 eugenol), but had high mean survival (>90%) following a 10 h simulated transport at a loading density of 480 g L-1 (two times the industry standard). Therefore, when using AQUI-S®20E to sedate fish during transport, it is important to consider how species and loading density will impact sedation. Loading density appears to have a negative effect on the level of sedation reached. Additionally, individual species appear to respond differently to sedation. Overall, results indicated that AQUI-S®20E sedation during fish transport has the potential to allow fish haulers to transport at increased loading densities.