The oyster population in Maryland's Chesapeake Bay more than tripled in the past 20 years

Maryland's oyster population has more than tripled in the past 20 years, according to data released Monday from the Maryland Department of Natural Resources and the University of Maryland Center for Environmental Science.

The jointly issued findings show positive trends for the keystone Chesapeake Bay species.

What does the assessment show?

According to the latest stock assessment, more than 12 billion oysters, including about 7.6 billion adult oysters and over 5 billion juvenile oysters, known as spat, currently live in Maryland's waters of the Chesapeake Bay.

The 2025 stock assessment represents the second major evaluation of eastern oysters in Maryland waters, as required by the state's Sustainable Oyster Population and Fishery Act of 2016.

This represents a dramatic increase from just 2.4 billion adult oysters in 2005.

Mike Wilberg, a professor at the University of Maryland Center for Environmental Science who led the assessment, attributed the growth to three main factors.

"The first one is that we have had some good spat sets," Wilberg said. "The second one is that natural mortality rates, or particularly disease, haven't been as bad as it was in the 1980s and 1990s."

Wilberg added that DNR's harvest restrictions have allowed oysters to "continue to survive and reproduce and provide habitat."

How well are oyster populations performing?

Most areas of the Chesapeake Bay are seeing oyster population growth, according to the report. One area has already reached the long-term abundance target.

24 areas show healthy growth between target and cautionary levels. Only ten areas show concerning patterns - three between cautionary levels and the lower limit, and seven below the lower limit.

"The oyster population has been increasing across most of the Bay," Wilberg said. "There are only a few areas where we have had decreases over the last five years."

While progress is encouraging, Wilberg cautioned that reaching ideal population levels remains a long-term goal that "may take decades or longer."

Oysters vital to Maryland's economic growth

Oysters are not only critical to the Chesapeake Bay's ecosystem. They also play a key role in Maryland's economy.

Maryland's seafood industry contributes about $600 million annually to the state's economy.

Within the last three years, Maryland has seen a collected a record number of oysters.

Oysters also help improve the Chesapeake Bay's water quality, with adult oysters filtering up to 50 gallons each day, according to the Chesapeake Bay Foundation.

The Environmental Protection Agency estimates that water clarity improvements to the bay could drive up property values in Maryland.