A Closer Look

The Bay


The largest estuary in the United States, the Chesapeake Bay is home to more than 3,600 species of plants and animals. Nearly 17 million people live in the Bay watershed.

The Bay is about 200 miles long, stretching from Havre de Grace, Md., to Norfolk, Va. Its width varies from 3.4 miles at its narrowest point near Aberdeen, Md., to 35 miles wide near the mouth of the Potomac River.

The Bay has an average depth of 21 feet. Most of the Bay is very shallow — six feet deep or less in more than 700,000 acres. But some channels are more than 100 feet deep.

The Bay yields 500 million pounds of seafood — including crabs, oysters and rockfish — each year. (Learn more about the Chesapeake Bay)

About the Blue Crab

  • The “blue crab” gets its name from its brilliant blue claws.
  • A crab’s gender can be determined by the shape of its underside “apron.” The male crab’s apron is shaped like an inverted “T.” An adult female’s apron is broad and rounded, while an immature female’s is triangular. Red tips on the claws also indicate that the crab is female.
  • A female carrying a cluster of orange eggs beneath her apron is known as a “sponge crab” and is nearly ready to spawn.

The blue crab is rapidly disappearing from the Bay, and the main culprits are the excess nitrogen and phosphorus found in lawn and other fertilizers, animal manure, wastewater and automobile emissions. The nutrients flow into the Bay and fuel algae growth. As algae bloom, they block out the sunlight that underwater bay grasses — which serve as a “nursery” for juvenile blue crabs — need to grow. And then, after algae die and decompose, they consume the oxygen that the crabs need to live.

Fortunately, simple steps such as using lawn fertilizer properly can help restore and protect the Bay—and the blue crab.