ANNAPOLIS, Md. — Maryland’s oyster population in the Chesapeake Bay is showing strong signs of health, according to preliminary findings from the Maryland Department of Natural Resources’ 2024 Fall Oyster Survey. The spatfall intensity index, a key measure of oyster reproduction and potential growth, exceeded the 39-year median for the fifth straight year. This follows a standout 2023, when reproduction hit remarkable levels, setting the stage for continued recovery.
The survey, conducted from Oct. 8 to Nov. 25, 2024, across Maryland’s oyster-growing waters, found that last year’s spat—now classified as “smalls”—were plentiful in many areas. These young oysters signal a positive outlook for both the commercial fishery and the Bay’s sanctuaries. Notably, a rare, robust spatset from 2023 in the upper Potomac River weathered high freshwater flows this past winter and spring, with little mortality despite stunted growth from lower salinity. Disease levels, a concern in 2023, also dropped significantly in 2024 due to wet weather early in the year.
“The 2024 Fall Survey confirms Maryland’s oyster population is doing well, with the key indicators showing encouraging results,” said Christopher Judy, director of the Department of Natural Resources Shellfish Division. “Certain low salinity regions still need to improve, but overall the findings are promising for the near-term future of this vital species.” The survey, one of the world’s longest-running oyster monitoring efforts at 85 years, sampled 364 locations across nearly 300 oyster bars, including harvest areas, seed sites, and 95 bars in 38 sanctuaries.
The 2024 results contrast with 2023, when drought-driven high salinities boosted reproduction but also spread diseases like MSX and Dermo. MSX reached as far north as Hacketts Point near the Bay Bridge, while Dermo rose above its long-term average. Heavy rains from December 2023 to May 2024 reversed this trend, slashing salinity levels—by half in areas like the Choptank River—and curbing both diseases. In 2024, MSX prevalence hit a low of 0% in 17 of 26 tested samples, with a peak of just 7%. Dermo also declined sharply, and mortality stayed low to moderate, below the 40-year average for the 20th consecutive year.
Oyster biomass, reflecting population size and weight, rose 5% from 2023, marking the third-highest level in 32 years and a 62% gain over the long-term average. The cultch index, which tracks habitat quality, hit its second-highest three-year average in two decades, up 28% from last year. Strong cultch levels shone in Tangier Sound, the Choptank River tributaries, and the Patuxent River, while the main Bay and Chester River lagged. A crushed concrete planting in Pocomoke Sound yielded the survey’s top natural spatset, per Maryland DNR data.
The Chesapeake Bay, spanning 64,000 square miles, supports a $1 billion oyster industry, according to the Chesapeake Bay Foundation. Maryland’s efforts mirror regional restoration work, like Virginia’s oyster reef projects, noted on its state website. The survey’s full findings will be presented to the Oyster Advisory Commission on March 17, 2025, with a summary posted on the Maryland DNR website.
Despite a weaker 2024 spatset compared to 2023, recruitment remained above average and reached north of the Bay Bridge—a rare event. Drought returned late in 2024, but colder winter waters are expected to keep diseases in check. These trends bolster hope for the Bay’s oyster future.
