Abstract.— West Texas saline groundwaters were assessed as potential media for culturing red drum, Sciaenops ocellatus. In 30‐d bioassays with juvenile red drum (0.4–3.0 g), highest survival was 85% in a 5‐ppt (parts per thousand = g/L) salinity, high‐sulfate (1,723 mg/L SO4‐2), high‐calcium (427 mg/L Ca±2) groundwater from a windmill catchment pond in Pecos County. The lowest survival was 0% in a 35‐ppt saline groundwater from a gravel pit, also in Pecos County. In complementary bioassays of low‐salinity (<5 ppt) groundwaters from the same region, calcium chloride (CaCl2) addition to a 3‐ppt. Reeves County ground‐water low in Ca±2 resulted in the greatest increase in survival (0–93). It was unclear whether the beneficial effect of CaCl2 was a result of increasing Ca±2 concentration (36–336 mg/L), increasing Cl‐ concentration (639–1,296 mg/L). or both. The concentration of total dissolved solids (“salinity”) appears to be the single most important consideration in estimating the red drum aquaculture potential of a groundwater, with the optimum salinity being 5–15 ppt. Concentrations of arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), and selenium (Se) tended to be higher in west Texas groundwaters than in typical U. S. surface waters. However, based on current maximum tolerable daily intake recommendations, red drum cultured for 30 d in west Texas groundwaters contained whole‐body As, Cd, Cr, Hg, Pb, and Se concentrations that would not pose a substantial health risk to adult human consumers.

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To evaluate the value of transporting fingerling walleyes Stizostedion vitreum in buffered sodium chloride, we monitored blood chemistry, behavior, and water quality in conjunction with two 5-h transport trips. The control salt mixture was 0.50% sodium chloride (NaCl), and the buffered treatment was 0.45% NaCl and 0.05% sodium bicarbonate (NaHCO 3 ). We also collected posthaul blood samples from walleyes 2 h after they were placed into cages in East Okoboji Lake, as well as daily during a 72-h recovery period in hatchery raceways. Behavior was tested before and after hauls to quantify any disorientation that might occur as a result of hauling procedures. The addition of NaHCO 3 to hauling-tank water significantly increased the pH and alkalinity of the water compared with the unbuffered control. Overall, buffering produced significant effects on water chemistry but only minor effects on physiological measures of stress and the acid-base balance. In part, the effects of ram-air ventilation in removing excess CO 2 and the fact that the water had moderate alkalinity levels to begin with negated the beneficial effects of buffering. Buffering is likely to confer benefits in situations where is alkalinity is low and there is poor ventilation of the hauling tank. Before and after hauls, we tested the preference of walleyes for a black or white tank background with a simulated predator (black brush). In both hauls, before the haul fish in all groups chose a black background more often than the white background. After hauling, fish in the control group sometimes showed preference for a white background, but fish in the buffered water never showed a preference for a white background. Many fish stocked directly into the lake remained near the lake bottom close to the boat ramp for at least 5 h after stocking. The most conspicuous changes in blood chemistry occurred in fish 2 h after they were stocked into floating cages. Our results suggest that fingerling walleyes are disoriented following a 5-h haul and would benefit from a recovery period prior to stocking.

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We investigated the effect of dietary protein level (41 or 61%) on the total ammonia nitrogen (TAN) excretion by fingerling walleyes (Stizostedion vitreum) at 21°C. Total ammonia nitrogen concentrations ranged from 0.06 to 0.75 mg/L and were positively correlated with tank biomass (41% protein, r = 0.72, P < 0.01; 61% protein, r = 0.83, P < 0.01). The overall between-treatment difference in excretion rates, 28.1 versus 29.2 mg TAN/kg fish per hour for 41 and 61% protein diets, respectively, was not significant. Fingerling walleyes fed 41 or 61% protein feed produced an estimated 14.3 and 14.4 g TAN/kg feed per day.Ammonia is the main nitrogenous excretory product offish and is derived from dietary protein digestion and amino acid cataholism. The toxicity of nitrogenous excretory compounds is the most limiting factor in intensive fish culture (Colt and Armstrong 1981). High but sublethal environmental ammonia concentrations have been associated with gill damage and reduced growth (Meade 1985). Empirical information on ammonia excre-