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Man and woman holding fish

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FWC staff members collect blood from a female red drum. Nitrate is a potentially toxic by-product of fish metabolism that accumulates in recirculating aquaculture. Recirculating aquaculture uses specialized filtration to recycle 80-100% of the water continuously rather than replacing water daily to remove fish wastes. Recent evidence suggests that low levels of nitrate might contribute to reduced egg quality in female broodstock red drum Sciaenops ocellatus. During a long-term study FWRI staff investigated the effect of nitrate on spawning of red drum (often called redfish) at the Stock Enhancement Research Facility. During this study, survival and size of eggs and larvae were tracked over the reproductive season and blood was collected routinely from female red drum for measurement of reproductive indicators.