Author
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Ludwig, Gerald |
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Submitted to: American Fisheries Society Annual Meeting
Publication Type: Abstract Only Publication Acceptance Date: 8/20/2001 Publication Date: 8/20/2001 Citation: LUDWIG, G.M. SUNSHINE BASS FINGERLING PRODUCTION IN PONDS - THE EFFECT OF MORE ORGANIC AND INORGANIC FERTILIZER.. AMERICAN FISHERIES SOCIETY ANNUAL MEETING. 2001. p.192. Interpretive Summary: Technical Abstract: Sunshine bass fingerling culture ponds were fertilized over a six week period with a combination of organic (rice bran at 472 kg/ha) and inorganic (liquid 9-27-0 NPK at 216.2 kg/ha) fertilizers and at two, three, and four times that rate to determine if survival and growth of fry could be improved. Shortly after fry were stocked at four days of age, one of their first natural foods, rotifers, became progressively more abundant as fertilizer application increased. Ponds receiving increased amounts of fertilizer also had increased amounts of crustacean zooplankton: copepod nauplii, copepods, and cladocerans that also are important natural foods for sunshine bass fingerlings. Even though increased amounts of fertilizer resulted in increased concentrations of natural feed, fingerling survival decreased from a mean of 47% for the base level fertilizer treatment to 15.4% for ponds receiving four times as much fertilizer. Increased fertilizer application adversely affected water quality that probably detrimentally affected fish survival. Unionized ammonia nitrogen levels, pH and water temperatures in all treatments were at or above concentrations reportedly lethal to sunshine bass fry at or shortly after fry were stocked. Differences in levels of unionized ammonia nitrogen were correlated with differences in final survival. Low dissolved oxygen concentrations and chronic sub-lethal levels of unionized ammonia in the more highly fertilized treatments probably exacerbated differences in mortality among the treatments. |
