Nutrient requirements of walleyes (Stizostedion vitreum vitreum)

Abstract

1985). Third, fisheries products represent a significant portion of the national trade deficit. Fourteen percent, or 4.1 million dollars, of the annual merchandise trade deficit for 1984 was attributed to fisheries products (Aquaculture Magazine, 1985). Development of the aquaculture industry in the United States could result in a reduction of this deficit. The production of several species of fish in the U.S. has developed into profitable industries. The production of rainbow trout in the United States has increased greatly since the early 1950s. In 1954, the annual production of farm-reared rainbow trout (Salmo gairdneri) was 450 metric tons. By 1972, production had increased to 13,400 metric tons (National Research Council, 1978) with production almost doubling during the succeeding 10 years to a total of 21,800 metric tons (National Aquaculture Development Plan, 1983). The culture of channel catfish (Ictalurus punctatus) in southeastern U.S. has also evolved into a viable industry. Production of catfish increased from 4,000 metric tons in 1969 (National Research Council, 1978), to 34,855 metric tons in 1980 and than to 90,900 metric tons in 1982 (National Aquaculture Development Plan, 1983). The industry experienced a 400% increase in production between 1980 and 1985 without substantial decreases in price (Rhodes, 1987). Farm-raised catfish is now a regular menu item for several national restaurant chains such as Churches Fried Chicken, Golden Corral Steak House, Red Lobster and Long John Silver's Seafood Shop (Rhodes, 1987). Many other species are being investigated for aquacultural development.

Ammonia Excretion by Fingerling Walleyes Fed Two Formulated Diets

“…The findings of our study and those from Barrows (1987) indicate that a dietary protein level of 61 % is excessive when fingerling walleye are fed 5-10% of their body weight daily.…”

“…Therefore, because the energy density of the 61% protein feed was greater, the fingerling walleyes fed the 61% protein diet may have consumed less feed than the walleyes receiving the 41% protein feed. Barrows (1987) found that, at 21°C, weight gain of fingerling walleye increased linearly with increasing dietary protein to a breakpoint of 50% protein for 8-g fish and 42% protein for 50-g fish.…”