Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: August 7, 2003
Publication Date: March 1, 2004
Citation: Riche, M.A., Gallagher, K.A., Weirich, C.R. 2004. Effect of direct freshwater transfer on indicators of acute stress in saltwater acclimated summer flounder paralichthys dentatus. Aquaculture America Conference. 2004 Book of Abstracts. p.500. Technical Abstract: Summer flounder (Paralichthys dentatus) is a euryhaline flatfish species with both recreational and commercial value. They are known to migrate between estuarine and shelf waters along the Atlantic coast, and have been found in salinities as low as 1ppt. Their ability to survive and flourish in low-salinity environments makes summer flounder an ideal marine species for culture in underutilized inland areas obviating the need to site farms on expensive coastal land. Despite their ability to tolerate a wide salinity range it is not known how transfer from a hyper- to a hypo-osmotic environment affects the acute and chronic stress of maintaining physiological homeostasis. The objective of this study was to determine the effect of transfer from saltwater to freshwater on indicators of acute stress and to determine recovery time following direct transfer to freshwater. Six fish, approximately 100 g each, were stocked into one of 18 60-L tanks receiving flow through seawater. An additional six fish served as a time 0 baseline. Tanks served as the experimental units. Following a seven-day acclimation period, the experimental units were slowly drained to 8 L and half were switched to flow through freshwater and half remained on flow through seawater, thereby initiating the experiment. Each experimental unit was randomly assigned a time point for sampling. The fixed factor treatment effects included salinity (freshwater and saltwater) and time intervals following transfer to freshwater (1, 2, 4, 8, 12, 24, 48, 96, and 168 hours). The experiment was repeated four times with each trial serving as a replicate. At the assigned sampling time fish were anesthetized in the tank with 5 mg/L metomidate and approximately 1 ml blood drawn via caudal puncture. Glucose and hematocrit were measured on whole blood from each individual. Total serum protein, chloride and osmolality were measured using aliquots of serum pooled by experimental unit. Whole blood and serum parameters were analyzed to determine peak response and recovery time. The results of this experiment will assist in determining the extent direct transfer of salt water acclimated summer flounder to freshwater has on the acute stress response of summer flounder and provide baseline information on some serological parameters. The information can be used to assist in developing appropriate acclimation procedures for transferring summer flounder from a saltwater to a freshwater environment.