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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetics, Physiology, and Health Research to Improve Catfish Production

Location: Warmwater Aquaculture Research Unit

Title: Effects of salinity on growth and ion regulation of juvenile alligator gar Atractosteus spatula

item Schwarz, Daniel
item Allen, Peter

Submitted to: Aquaculture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2014
Publication Date: 2/1/2014
Citation: Schwarz, D.E., Allen, P.J. 2014. Effects of salinity on growth and ion regulation of juvenile alligator gar Atractosteus spatula. Aquaculture Research. 169:44-50.

Interpretive Summary: Alligator gar are an important conservation aquaculture species, and have been cultured for commercial aquaculture in the past. Juvenile survival and physiological performance were tested in a range of water salt concentrations. Juvenile alligator gar can survive for long periods in water salt concentrations greater than internal concentrations of salts, but require access to fresh water for long term survival and best growth.

Technical Abstract: The alligator gar (Atractosteus spatula) is a primitive euryhaline fish, found primarily in estuaries and freshwater drainages associated with the northern Gulf of Mexico. The extent of its hypo-osmotic regulatory abilities is not well understood. In order to determine how salinity affects growth rates and ionic and osmoregulation, juvenile alligator gar (330 days after hatch; 185 g)were exposed to 4 different salinities (0, 8, 16, and 24 ppt) for a 30-day period. Specific growth rate, plasma osmolality and ion concentrations, gill and gastrointestinal tract Na+, K+-ATPase activities, and drinking rate were compared. Juvenile alligator gar were able to tolerate hyperosmotic salinities up to 24 ppt for a 30 day period, albeit with decreased growth resulting largely from decreased food consumption. Plasma osmolality and ionic concentrations were elevated in hyperosmotic salinities, and drinking rates and gastrointestinal tract Na+, K+-ATPase activities increased, particularly in the pyloric caeca, presumably the primary location of water absorption. Therefore, juvenile alligator gar < 1 year of age are capable of prolonged exposure to hyperosmotic salinities, but, based on the inference of these data, require access to lower salinities for long-term survival.

Last Modified: 06/23/2017
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