Yearly oyster reproduction surveys and accounts from watermen will tell you that the Chesapeake Bay wild oyster population is getting better and better. Now, the state has a long-term snapshot of the oyster population growth… and it brings encouraging news.
The 2025 benchmark stock assessment shows that the Maryland oyster population has tripled in the last 20 years to more than 12 billion oysters. The Maryland Department of Natural Resources (DNR) and the University of Maryland Center for Environmental Science released the summary results of the stock assessment on Monday.
The stock assessment looks at the eastern oyster in the Chesapeake Bay from 2005 to 2024. Why 2005? It marked a low point shortly after oysters were decimated by disease. That year, there were only 2.4 billion adult oysters.
Since then, overall oyster abundance has increased to 7.6 billion adult oysters (plus 5 billion spat) in the Maryland section of the Bay. University of Maryland Center for Environmental Science Professor Mike Wilberg attributes the success to some good spatsets (where oyster larvae successfully latch onto a solid surface, like an oyster reef, and grow to become juvenile oysters); lower disease rates than in the 1980s and ’90s; and harvesting restrictions that have allowed oysters to survive and reproduce.
This chart shows the population growth over the past 20 years:
Just since the last stock assessment was completed in 2018, there has been measured population growth at protected oyster sanctuaries and decreased fishing pressure in harvest areas.
Fishing pressure refers to whether the fraction of the population watermen are harvesting still allows the oyster population to remain sustainable. The 2025 assessment found 29 out of 35 areas have low fishing pressure. In 2025, only four areas were over the limit for high fishing pressure. When fishing pressure is high, oyster populations may not grow over time and could begin to decline. This year’s assessment shows a big improvement from 2018, when 19 areas were over the limit.
Scientists gathered much of their data for the benchmark stock assessment from DNR’s fall oyster survey. In 2024, the survey showed the oyster population to be “in good shape”. Baby oysters, or spat, were seen even in areas that haven’t had any reproduction in a generation or two.
Along with the fall survey, the 2025 stock assessment also included data from Maryland’s Bay bottom survey, sonar surveys, plantings, patent tong surveys, harvest reports, peer-reviewed studies, and even the state’s “Yates survey” that mapped oyster bars starting in 1906, DNR says.
The assessment is required by state law to be done at least every two years. The Chesapeake Bay Foundation fought for the state law, passed almost a decade ago. Bay Foundation Maryland Executive Director Dr. Allison Colden calls oyster restoration “one of the Chesapeake Bay’s greatest success stories.” She says, “The strong results should encourage us to maintain, and even accelerate, the momentum for large-scale oyster restoration.”
She says DNR must continue carefully monitoring the oyster population, since threats like environmental conditions and disease can change things quickly.
DNR is looking down the road, too. Wilberg allows that the state’s long-term abundance target is just that: a long-term goal. “It may take decades or longer for the population to get back up to those levels,” he said. “This is where we want the population to get to, but we’re not there yet.”
“Good news for oysters is good news for the Chesapeake Bay,” DNR Secretary Josh Kurtz said. “This stock assessment shows that oysters have made important progress during the past two decades. That’s a testament both to our continued investment in oyster restoration and our careful management of the oyster fishery. These findings will help guide management decisions during the next several years.”
