A new report on the Chesapeake Bay’s signature blue crab has documented a steep, long-term decline in the crustacean’s population, raising concerns among environmental groups about the future of one of the region’s most important species.
Scientists aren’t sure exactly what’s behind the drop. The total number of blue crabs can fluctuate sharply, with population estimates varying by tens of millions — or even hundreds of millions — within just a few years. But experts said they’re concerned by what they’re seeing.
“It’s clear the bay’s most iconic species is under immense stress,” according to the Chesapeake Bay Foundation, which was not involved in the assessment but whose scientists closely monitor its results.
There are numerous ways to gauge crab “abundance,” the term researchers use to denote the overall population or that of different subgroups, such as juveniles. Michael Wilberg, the assessment’s lead author, cited one overarching finding: In 2011, the bay had about 1.3 billion crabs. By 2023, that dropped to about 825 million, he said.
Habitat loss, especially the reduction of underwater grasses that shelter young crabs, may be playing a role, experts said. Changes in currents, winds and storms, pollution and runoff, and low-oxygen “dead zones” caused by algae blooms may also contribute, experts said.
“They’re a short-lived species and the biggest thing we’re seeing is a decline in the number of young crabs entering the population,” said Chris Moore, the Chesapeake Bay Foundation’s Virginia executive director. “That long-term trend of fewer young ones is very concerning.”
Healthy blue crabs are vital to the bay’s ecosystem. They eat worms, clams, and smaller crabs, and are prey for fish, great blue herons, and sea turtles. Blue crabs also generate $50 million to $80 million annually for the commercial crabbing industries of Maryland and Virginia, experts said.
