( come into play. Berlinsky's team found...)Uncovering sex-change secrets of black sea bass

Berlinsky is continuing his experiments to clarify the role that water temperature plays and to further understand what factors determine the initial sex of captive-born fish. He's also collaborating with Canadian researchers to study the underlying biochemical mechanisms that cause the fish to change sex. In female fish, estrogen plays the major role, he said. In males, a steroid hormone called 11-ketotestosterone is involved. The scientists are now studying those hormones as well as the enzymes that control them.

By turning off estrogen production, Berlinsky says, he can turn a female fish into a male within a week. Giving 11-ketotestosterone to a female converts it into a male. "We're studying the ways to control the enzymes that control sex reversal," he explains. "We're coming at the problem both behaviorally and biochemically."

Though he still has details to sort out, Berlinsky believes he has already made important steps. "We have already made progress, determining optimal sex ratios and delaying sex reversal by controlling density," he notes. "We've already made strides toward making black sea bass aquaculture possible."