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~ -.J W --J San Joaquin Valley farm lands, the most productive in California, would go out of production because of accumulation of salts in soils In the next two decades unless adequate drainage is provided. Condensed with permission from the April 15. 1982, "Water Desalination Report." Tilapia in Salty Water Saline water may have another beneficial use-aquaculture. Steve Grabowski, a research fishery biologist in the Bureau of Reclamation, is studying the possibilities of aquaculture-growing fish in saline water. He believes that jf the fish can survive and grow in this water, it will provide another means of using, rather than wasting, precious Colorado River water. The first phase of the study involved setting up the laboratory equipment, which is much more involved than buying two 2~allon fish tanks. putting salty water in one and fresh water in the other, and adding the fish. The laboratory. also used by a Fish and Wildlife Service cooperator, is called a wet lab, and is equipped with hot and cold water to allow blending water to attain correct water temperatures for experiments, drain channels, and a compressed air system, to allow for maximum versatility in setting up various flow-through or recirculating culture systems. Dechlorinators treat all incoming water. Recirculating systems require adequate filtration to reduce levels of ammonia and remove waste materials. The saline water used in the experiment is from the hot pools near Glenwood Springs having a salinity level of around 19.000 mglL, about half the salinity of sea water. The species currently being used in the study is Tilapia aurea, commonly called blue tilapea (basically a dark fish known for its relative ease of culturing and noted for its excellent taste). The 4-6 inch tilapia survived the initial 96-hour salinity tolerance test with no losses, after a direct transfer from fresh water to salt water. Tilapia are now being subjected to a test to evaluate long-term survIval and groVv1h. Other fish used in the study are rainbow trout. channel catfish, and a hybrid striped bass produced by female striped bass and male white bass. Presently the bass used in the experiment are only about two inches long but they, too. have passed the 96-hour tolerance test and will be used in the testing program when they reach about 3-4 inches. The tilapia continue to survive and grow in the saline water recirculating system at about SOOF. Tilapia in a recirculating fresh water system serve as a control. A control is necessary to determine if "handling procedures" may be a cause for slower growth or mortality instead of the experimental saline water. All fish are measured and weighed each week to see how fast they are growing. The same percent body weight offood (catfish food) is provided to both groups. The fish have been In the experimental conditions for about two months. The fish in saline water are surviving but eating less with a resultant slower growth rate. Steve probably will continue this study for another year to learn what effects the saline environment has on the long term growth rate and behavior of the fish. Next year Steve plans to expand his experiments to include the survival and growth of shellfish-shrimp, lobster. oysters. or clams-and vegetation. If adequate survival and groVv1h of various finfish and shellfish species occur in saline waters, state, federal or private entities may want to utilize the currently undesirable saline waters from the Colorado River or other western rivers for a beneficial purpose. For questions concerning projects discussed in this newsletter, please contact the Public Affairs Office in the Region responsible for that project. Bureau of Reclamation Upper Colorado Regional Office P.O. Box 11568 Salt Lake City. Utah Telephone: Commercial: 84147 FTS 588-5403 801-524--5403 Bureau of Reclamation Lower Colorado Regional Office P.O. Box 427 Boulder City, Nevada Telephone: Commercial: 89005 FTS 598-7420 702-293-8420 For answers to general questions or items you would like to see included in SALINITY. UPDATE. write to: Editor, SALINITY UPDATE, 0-1000 Colorado River Water Quality Office Bureau of Reclamation P.O. Box 25007 Denver Federal Center Denver, Colorado 80225 Telephone: Commercial: FTS 234-4180 303-234-4180 GPO 837 - 113