Fecundity and egg size of brook trout and brown trout brood stocks in heated, recirculated water
Fisheries Bioengineering Symposium: American Fisheries Society Symposium 10
Colt J;White RJ;
American Fisheries Society
Heating and recirculating water at a brood-stock station resulted in increases in individual fecundities, egg sizes, and volume of eggs produced per kilogram of fish for brown trout Salmo trutta and brook trout Salvelinus fontinalis . Relative fecundities increased in brook trout but did not vary predictably in brown trout. In the original station, mean weekly water temperatures ranged from 0.0ºC in winter to 15.0ºC in summer. Since 1984, water temperatures have been kept at 8.0-10.0ºC year-round with 80% of the water being recirculated each cycle. After renovations, brook trout fecundities increased from 556 to 1,789 eggs/female (2,298 to 3,806 eggs/kg) for 2-year olds, 1,455 to 4,071 eggs/female (2,778 to 3,232 eggs/kg) for 3-year olds, and 4,514 to 5,920 eggs/female (3,224 to 3,947 eggs/kg) for 4-year olds. The size of brook trout eggs increased from 26,340 to 16,974 eggs/L, 21,370 to 13,423 eggs/L, and 15,351 to 13,796 eggs/L for 2-, 3-, and 4-year olds, respectively. The volume of eggs produced per kilogram of female rose from 0.087 to 0.22 L/kg for 2-year olds, 0.13 to 0.24 L/kg for 3-year olds, and 0.21 to 0.29 L/kg for 4-year olds. Individual fecundities of brown trout increased from 1,279 to 1,798 eggs/female for 3-year olds, and from 1,695 to 3,629 eggs/female for 4-year olds. Within age-3 fish, the volume of eggs produced per kilogram of female was 0.20 L/kg both before and after renovations, whereas the value for 4-year-olds doubled from 0.14 to 0.28 L/kg after renovations. The size of brown trout eggs increased from 16,027 to 13,255 eggs/L and from 16,027 to 9,230 eggs/L for 3- and 4-year olds, respectively. These improvements in fecundities and egg sizes were attributed to the heavier mean weights and more efficient egg production of the brood trout held in constant-temperature water. These results demonstrate the feasibility of successfully rearing trout brood stocks in heated, recirculated water.