Back from the Brink or Still in Trouble? A bushel of lively blue crabs is a common sign of summer around Chesapeake Bay.
Back from the Brink or Still in Trouble? A bushel of lively blue crabs is a common sign of summer around Chesapeake Bay. Grisham The fact that we can't control Mother Nature makes it even more imperative that we focus on the elements we can control, especially reducing pollution to the Bay and maintaining sufficient numbers of spawning-age crabs.
Also known as "beautiful swimmer," the blue crab is one of the more resilient of Chesapeake species, but its fate depends on many factors.
With the drastic decline of the Bay's oysters in the s, watermen began extending their crabbing efforts much later into the fall, the time they would normally have shifted to oystering. A decade or so later, the crab population had been cut in half to around million. Not only was the blue crab itself depleted, so too were the oyster reefs and underwater grasses that provide it with food, shelter, and oxygen.
New science-based guidelines were established inrequiring a reduction of the catch of female crabs to a sustainable level.
Within two years the population had doubled and watermen and fisheries scientists were hopeful the Chesapeake bay s blue crab was coming back from the brink. But insurvey numbers dropped back to million. In a recommended target of million spawning age female crabs and a threshold of 70 million were adopted by Maryland, Virginia, and the Potomac River Fisheries Commission.
The winter dredge survey found the abundance of these females dropped below the recommended target but remains well above safe levels. This most recent survey placed the total number of crabs at million.
Find out more about the state of today's blue crab fishery. The Bay's blue crab population has always been prone to fluctuation, but it is clear it would be strengthened by improved water quality and crab habitat.
Reducing the levels of nutrients reaching the Bay from farms and lawns and better managing stormwater runoff before it gets into rivers and streams, will help mitigate weather extremes, improve water quality, and contribute to the recovery of both blue crabs and Bay grasses.
Creating a Sustainable Fishery The crab population is truncated, meaning we catch crabs so quickly, there are very few crabs bigger than legal size.
As a result, the fishery is very dependent on each year class that comes in.
That creates instability, which is not a good thing for the crabs or the crabbers. We want more older crabs in the crab population so that we have ongoing high reproductive potential—which helps stabilize the population, and larger crabs on average in the catch—which are the most valuable in the market.
Essential for building stability in the crab population is for Maryland and Virginia to continue applying the science-based guidelines for managing the fishery adopted inwhich help avoid the overfishing of previous years. And you can't take 70 percent of the trees and still have a forest.
And if you take 70 percent of the crabs, you no longer have a healthy crab stock. The Fight to Shrink "Dead Zones" Another strategy to improve the long-term stability and health of the Chesapeake's crab populations is to cut significantly the nitrogen and phosphorus pollution into the Bay.
Nitrogen and phosphorus stimulate explosive growth of algae. Algal blooms darken the water, blocking light and killing underwater grasses that crabs need for shelter. Algal blooms fed by polluted runoff quickly die and decay, sucking up oxygen and creating "dead zones.
That is enough food to support half the commercial crab harvest. In an effort to shrink the Bay's "dead zones," the U. Environmental Protection Agency issued pollution targets for the Chesapeake Bay in Decemberresulting in the cooperative efforts of federal and state agencies in what is called the Chesapeake Clean Water Blueprint.
At the center of this effort are blue crabs and the more than 6, watermen and other workers who depend on the crabs for their livelihoods.The survey indicates a bay-wide crab population of million, a decrease from last year’s estimate of million, driven largely by a decrease in the number of adult crabs.
In , the spawning female stock decreased 42 percent from to million, dropping below the target level of million, but remaining well above safe levels.
The Bay’s signature crustacean supports important commercial and recreational fisheries. But pollution, habitat loss and harvest pressures threaten blue crab abundance. There is nothing more “Chesapeake” than the blue crab.
The Bay’s signature crustacean is one of the most recognizable. A sluggish male blue crab rests on the deck of the Virginia Institute of Marine Science (VIMS) R/V Bay Eagle after being caught by the Blue Crab Winter Dredge Survey in the lower stretch of the Chesapeake Bay near the mouth of the York River in Virginia on March 8, Dozens of feet below the surface of the Chesapeake Bay, the world is changing as we know it.
From the silty ocean floor, to the waves on the Bay’s surface, the marine ecosystem is starting to look different. Acres of the Bay’s brilliant green eelgrass are disappearing, causing blue crab to move.
The Chesapeake’s iconic blue crabs have shown steady improvement since a low point in The Winter Dredge Survey conducted by the Maryland Department of Natural Resources showed the the population remains within healthy, sustainable parameters.
While the cold winter resulted in a decrease in adult crabs, including spawning-age females, the juvenile population increased 34 percent.
The Bay’s signature crustacean supports important commercial and recreational fisheries. But pollution, habitat loss and harvest pressures threaten blue crab abundance. There is nothing more “Chesapeake” than the blue crab. The Bay’s signature crustacean is one of the most recognizable.