Gender-changing fish are studied

April 11, 2006

A University of New Hampshire scientist is trying to determine what causes sex reversals among black sea bass and how to prevent it.

Associate Professor of zoology David Berlinsky says the sought-after fish is a good candidate for aquaculture, except for its unpredictable tendency to change gender while in captivity.

"In the wild, black sea bass are born as females and turn into males at around 2 to 5 years old," Berlinsky said, but the sex change occurs more quickly in captivity.

George Nardi, vice president and director of a commercial fish farm in Newington, N.H., says the problem makes breeding the fish a tricky proposition.

"We invest in our brood stocks, the parents of the young fish, much as a thoroughbred horse farm invests in mares and stallions," said Nardi. "It doesn't do us much good if we always have to go out and get new females."

Berlinsky and his colleagues so far have discovered the fish are more likely to become males if raised at constant temperatures or when kept in crowded tanks.

Berlinsky is also collaborating with Canadian researchers to determine the biochemical mechanisms causing the gender changes.

Copyright 2006 by United Press International

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