Aquaculturists now can produce sunshine bass, the ever-popular hybrid fish,
more efficiently by preventing them from being gobbled up by one of their own
foods--zooplankton. Thats good news for sunshine bass producers--a small
but rapidly developing industry.
The trick: stock ponds with the fish when two other morsels, microscopic
rotifers and minute crustaceans, become plentiful but before zooplankton grow
large enough to devour the tiny, newly hatched fish.
As newly hatched fry, sunshine bass are 2 to 5 millimeters long and
vulnerable. Agricultural Research
Service scientists have developed charts and graphs that identify the
precisely timed window of opportunity when pond stocking allows
fish to eat and grow fast enough to avoid becoming prey for larger zooplankton.
Research showed pond temperature strongly affected the rotifer supply
buildup. And rainfall drove the growth of the crustacean copepod nauplii. Other
influences included day length, dissolved oxygen levels and the air temperature
Before sunshine bass--a cross between male
striped bass and female white bass--began making a splash, east coast fishermen
in the early 1980's annually peddled up to 14.7 million pounds of striped bass
to fish markets. Overfishing and pollution essentially destroyed the industry.
Since 1984, the annual production of sunshine bass has increased from 10,000
pounds to 15 million pounds.
Research on sunshine bass may improve the culture of additional tasty
species of fish like yellow perch and walleye. If technology affords consumers
year-round choices from among several cultured species, steady buying habits
may develop. Then farmers may not have resources lying idle much of the year.
The scientists are researching ways to manage fish so theyll spawn all
year round, and theyre developing know-how for providing a year-round
supply of live food.