Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: MONDAY, August 9, 1993 TAG: 9308090073
SECTION: VIRGINIA PAGE: C3 EDITION: STATE
SOURCE: Associated Press
DATELINE: LENGTH: Medium
At the same time, scientists are studying the blue crabs' life cycle to keep numbers plentiful in the bay.
Scientists are perfecting their counting methods, but last year they predicted the harvest would be poor, and it was the worst in a decade. This year's prediction calls for a somewhat better harvest.
In recent years, blue crab harvests have varied widely, ranging from 53 million to nearly 100 million pounds with values up to about $40 million.
Females mate once, in the hours before growing their final shell. For years, the crab seemed invulnerable because each female produces millions of eggs whose survival was thought to depend solely on climate forces such as currents. But recent research at the Virginia Institute of Marine Science found for the first time that the number of young hinges partly on the supply of adults.
That "means you can overfish them," Bill Goldsborough, a fisheries scientist with the Chesapeake Bay Foundation, told The Washington Post.
The dredge survey used for the count also found that crabs live in a wider variety of places around the bay than previously believed.
"People basically thought female crabs were in the lower part of the bay in the wintertime," said Brian Rothschild, a University of Maryland scientist and survey leader. "What we found were crabs were distributed all over the bay."
The count takes place in the cold months - December, January and February - when crabs rest in the bottom mud throughout the 4,000 square miles of the Chesapeake Bay and its tributaries. Dredges drag the bottom at 1,500 locations and sort the catch by number, size and sex.
The winter dredge also is turning up young crabs hunkered down in shallow-water sea grass beds, not the deep waters they had been presumed to occupy.
Scientists at the Virginia Institute of Marine Science, the University of Maryland, and the Smithsonian's Environmental Research Center near Annapolis also are looking into the crab's life cycle to better understand how to keep numbers plentiful.
Recent studies show that crabs are vulnerable not only to one another but also to human actions, such as the construction of shoreline homes that destroy habitat.
At the Smithsonian, scientists glued small crabs to string and left them out overnight; they found that 90 percent of the small crab mortality in some areas was caused by larger crabs. At the Virginia Institute of Marine Science, marine ecologist Romuald Lipcius cut open large crabs and examined their stomach contents; 35 percent had crab remains.
by CNB