BAFFLE USAGE IN COVERED RACEWAYS

Baffle usage was examined during culture of rainbow trout Oncorhynchus mykiss in covered raceways at McNenny State Fish Hatchery, Spearfish, South Dakota. Baffles had no noticeable impact on fish growth, feed c onversion, or mortality. However, rainbow trout reared in baffled race ways had greater pectoral and pelvic fin erosion than fish raised in u nbaffled systems. Dorsal fins, though apparently unaffected by baffles , decreased in proportionate length after just 46 d of rearing. Outflo ws of total suspended solids were similar in baffled and unbaffled rac eways. Baffles are effective tools to move fish waste, maintain racewa y cleanliness, and help hatcheries meet pollutant outflow regulations. However, the decrease in fish quality, as measured by fin erosion, sh ould be considered before baffles are used.