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Researcher Seeks Better Production Systems for Sunshine BassBy Jim Core
June 15, 2004
An Agricultural Research Service scientist has taken several key steps toward the development of a year-round supply of sunshine bass fingerlings.
The research by Gerald Ludwig, a biologist with the ARS Harry K. Dupree Stuttgart National Aquaculture Research Center in Arkansas, involves small zooplankton called rotifers. Ludwig has found that sunshine bass must be stocked just before rotifers become the dominant zooplankton in production ponds where small fish, called fry, are raised. Sunshine bass, being smaller than wild striped bass, can't feed on larger crustaceans and need the smaller rotifers as a food source.
Ludwig developed equations to predict when rotifers will make their appearance in outdoor fry production ponds. He and ARS agricultural engineer Tim Pfeiffer also devised an automated indoor feeding system for rotifers, ensuring that fry will have live rotifers throughout the year.
Demand for farm-raised sunshine bass--also known as hybrid striped bass--began in the mid- 1980s after supplies of wild-caught striped bass decreased. As part of his research, Ludwig studies the ecology of ponds where sunshine bass are raised. He also develops new methods of rearing fry indoors to increase production of fingerlings.
Typically, sunshine bass fry are raised in outdoor rearing ponds until they're 35-40 days old. Then they're called fingerlings and are fed commercial pellets. Fingerlings are generally available in the southeastern United States from May to June. If more fingerlings were available, especially year-round, they could increase production of market-sized fish and stabilize seasonal price fluctuations.
According to Ludwig, many factors are involved in timing fry stocking just right, including water temperature and the amount of forecasted rainfall.
Indoor production is required in temperate climates if producers are going to have a year-round supply of fingerlings. Ludwig produced hybrid striped bass fry in indoor tanks for the first time by feeding them freshwater rotifers, which he also cultured indoors.
Read more about this research in the June issue of Agricultural Research magazine.
ARS is the U.S. Department of Agriculture's chief scientific research agency.