Amid all this poaching, many male fish were killed, as were female sturgeon who had not yet reached reproductive age.

Attempts to fertilize the eggs of a rare female sturgeon caught in the Chesapeake Bay last year proved unsuccessful.

As a general rule, 10 percent of the weight of a female sturgeon consists of eggs (although pollution-related diseases have helped lower the figure in the Caspian.)

Besides the depredations of poachers, up to a third of the female sturgeon are suffering from chemical poisoning severe enough to render them infertile, scientists report.

And the proportion of female sturgeon reaching spawning grounds has also fallen, to just 20 or 30 percent.

"By the start of the caviar harvesting season in February of next year, we will be ready to take about one ton of caviar from our female sturgeon."

It is an economically crucial point, because every batch of caviar costs the life of a female sturgeon, so a fingerling must be raised to maturity to replace it.

One female pallid sturgeon that was caught in the upper Missouri River was estimated to be carrying 170,000 eggs, representing over 11 percent of its total body weight.

Usually, everyone grabbed handfuls from the first female sturgeon caught and gorged themselves.