BALTIMORE, MD—The Maryland Department of Natural Resources (DNR) announced that the preliminary results of its 2024 Fall Oyster Survey indicate that the Chesapeake Bay’s oyster populations are in good condition. The survey’s spatfall intensity index, a key indicator of reproductive success and potential population growth, was above the 39-year median for the fifth consecutive year.

This positive trend follows a remarkable year for oyster reproduction in 2023. The 2024 survey found that the 2023 year class oysters, known as “smalls,” were abundant in many areas, indicating a promising future for both the fishery and the Bay’s oyster sanctuaries. Notably, the once-in-a-generation spatset on the upper bars of the Potomac River appears to have survived the challenging conditions of the winter and spring, with minimal mortality observed.

Christopher Judy, Director of the Department of Natural Resources Shellfish Division, said, “The 2024 Fall Survey confirms Maryland’s oyster population is doing well, with the key indicators showing encouraging results. Certain low salinity regions still need to improve, but overall the findings are promising for the near-term future of this vital species.”

The annual Fall Oyster Survey, conducted from October 8 to November 25, 2024, is one of the longest-running continuous oyster monitoring programs globally. Biologists collected 364 samples from nearly 300 oyster bars, encompassing natural oyster bars, oyster seed production areas, seed and shell planting sites, harvest areas, and sanctuaries. The survey sampled 95 oyster bars in 38 sanctuaries.

The survey assesses the status of Maryland’s oyster populations using five key indices: spatfall intensity, oyster disease, total observed mortality, biomass, and cultch (a measure of habitat). The spatfall intensity and cultch indexes were derived from 53 long-term monitoring sites, while oyster disease levels were monitored at 43 sentinel disease sites, along with nine supplemental stations. Sentinel disease sites help determine biomass and mortality indexes.

The 2024 survey results represent a continuation of the positive trends observed in the 2023 survey, which was marked by widespread and high spat counts due to favorable salinity conditions. However, 2023 also saw an increase in oyster diseases, particularly MSX and Dermo. Consistent rains from December 2023 to May 2024 reduced the prevalence and intensity of these diseases.

While the latter half of 2024 saw a return to drought conditions, salinities remained favorable for another healthy spatset, though not as strong as the previous year. The survey also noted a small number of spat in the Bay north of the Bay Bridge, a rare occurrence.

Despite the overall positive findings, the DNR highlights the need for continued monitoring and management to address challenges, such as the impact of disease and low salinity in certain regions. The complete findings of the 2024 Fall Oyster Survey will be presented to the Oyster Advisory Commission at its March 17 meeting.

This article was written with the assistance of AI and reviewed by a human editor.

Photo via Maryland DNR

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