Summary
The Chesapeake Bay was once prolific with oysters. However, through many years of pollution, overharvesting, and disease, the bay oysters have declined significantly. This affects the health of the bay in several ways—by removing spawning grounds for other bay species, reducing water filtration, and removing shoreline protection. It also has a significant impact on the state’s seafood industry and those who rely on the bay to make a living. To help restore the Chesapeake Bay’s health, water quality, culture, and jobs, the state and its partners are investing in oyster restoration and aquaculture. One creative approach they are trying for promoting oyster aquaculture is through nutrient credit trading, an innovative way for municipalities and businesses to meet water quality permit requirements using oysters’ pollutant-filtering capabilities to remove nutrients from the water.
Learn more about the successes and challenges Gregorio Sandi, Chesapeake Restoration Section Head with the Maryland Department of the Environment (MDE), and partners encountered developing a nutrient credit trading market using oysters.

– Gregorio Sandi, Maryland Department of the Environment, Chesapeake Restoration Section Head Water and Sciences Administration
Lessons Learned
- Know your market. Know who’s going to buy credits, and make sure the short-term market will be there while you are getting off the ground while continuing to focus on long-term investment opportunities. There was a low demand due to pandemic-related closures. Therefore, oyster farmers were selling fewer oysters, which meant they were generating fewer credits. Additional challenges arose as regulated municipalities found other ways to meet water quality permit requirements, thus limiting the demand for credits.
- Make it easy for people to buy and sell credits. “One model we are exploring to improve buying and selling water and air quality credits is like a typical market platform, where credit sales are centrally managed by one entity and they can be purchased via a two-click solution,” shares Greg. In addition to ease of use, this tool would focus on marketing the credit generators, transparency for the process, and confidence that the buyer is getting what they pay for.
- Take into account government processes. Getting started takes longer than you think. Government processes and timelines are different than private sector. One of the first trades with Anne Arundel County took about one and a half years to get finalized since it had regulatory hurdles. The good news is that now the county has a process and more trades can happen faster.
- Set up a shell recycling program. Having access to oyster shells aids oyster restoration by growing and expanding oyster reefs. Microscopic oyster larvae attach to the shells, and these recycled shells can become home to dozens of baby oysters, called spat. This results in more oysters filtering pollutants. Every coastal town in Maryland now has one.
- Set oyster farmers up for success. A barrier to oyster aquaculture is having access to larvae and seed. This is where organizations like the Oyster Recovery Partnership, the Chesapeake Bay Foundation, and Ferry Cove can provide resources to help oyster growers.