Nighttime Lighting and Feeding in Ponds Enhance Survival of Fingerling Walleyes during Habituation to Manufactured Feed

Abstract

Our objective was to determine whether survival of fingerling walleyes Sander vitreus during the habituation interval in indoor tanks could be improved by means of night lights alone or by supplemental feeding near lights during the last half of the pond culture interval. At 17 d posthatch, walleye fry in one pond were exposed to 8 h of artificial lighting and were given supplemental formulated feed (L/F); another pond was exposed to 8 h of artificial lighting and no supplemental feeding (L/NF); and a third pond received neither artificial lighting nor supplemental feeding (NL/NF). After 44 d of pond culture, fish from the L/F pond were longer (mean ± SE = 40.3 ± 0.3 mm) and heavier (0.45 ± 0.003 g) than fish harvested from the L/NF pond (36.50 ± 0.29 mm; 0.35 ± 0.006 g) or the NL/NF pond (30.70 ± 0.17 mm; 0.25 ± 0.003 g). At harvest, nearly 85% of fish sampled from the L/F pond had lengths of 35–45 mm, whereas less than 5% of fish from the NL/NF pond were in this length-group. After the pond phase, survival during the 30-d tank habituation interval (used to wean the fish to formulated feed) differed among the three treatments; survival was 68.0 ± 1.3% for the L/F pond, 51.0 ± 3.8% for the L/NF pond, and 40.0 ± 3.8% for the NL/NF pond. At the end of the habituation interval, there was no difference in mean length (69.8–73.7 mm) or weight (3.0–3.5 g) among treatments. Mortality that was unaccounted for during the habituation interval—considered to be a measure of cannibalism—was not different among treatments. These results indicate that pond lighting, when combined with supplemental feeding or when used alone, can enhance growth of walleyes during the pond culture interval and can increase survival during tank habituation.