Oyster shells
Updated: August 16, 2021

Aquaculture has long been used in Maryland to help manipulate public harvest areas, as well as for private production of oysters. The State had an active program that returned shells from processing plants to natural beds. When the industry was highly productive, there were mountains of oyster shells in locations around the bays that were placed where it was judged they would be available for naturally produced larvae to attach to. These would then be either left in place to grow to market size in areas known for growth, or the small oysters moved to better growing locations, often in other county waters. The program often employed watermen and their boats during the spring of the year to do this work, between the ending of public harvest season for oysters and prior to when the crab harvest season picked up. It was largely paid for by a tax paid on each bushel of oysters landed from public reefs.

As the State developed need for more substrate than just the shucked shells, buried reefs of fossil oyster shells in the upper Chesapeake Bay were dredged and the substrate taken by tug and barges to various locations. These shells were smaller than the whole shells from processing plants but served as an excellent substrate for larvae to attach to in many areas. The “seed and shell program” was advised by oyster harvesters in each county elected to serve on local advisory committees. These groups were often interested only in enhancing their local areas and made demands on the resource management agency that were not supported by scientific evidence. One of the most egregious was the demand that oysters from potentially high disease areas be moved to areas where diseases had not previously been prevalent. These diseases thrived in high salinity and, when drought conditions in the 1980s caused elevated levels throughout Maryland waters, severe epizootics occurred that decimated the oyster resource and caused harvests to decline over ninety-five percent.

Commercial aquaculture was initiated in Maryland with passage of the “One Acre Law” in 1830 that allowed citizens to lease an acre of bay bottom to cultivate oysters. Maryland was one of the first states to pass such legislation and it was increased to five acres in 1865. By the end of the 1800s, it became apparent that overharvesting of the formerly virgin stocks was being carried out and the Haman Act in 1906 set up a new lease program and mandated the survey of naturally occurring oyster reefs that were charted, with the intent of keeping them in the public trust. Charles Yates, who carried out this survey, believed that there would be about 100,000 acres of public grounds and, within a few years, 200-300,000 acres of leased areas where people would raise oysters on privately managed grounds.

Leasing ground for private culture of oyster was always controversial in Maryland and led to many laws restricting what growers could do. This was changed with passage of a new lease law in 2009 that was combined into a statewide oyster management plan, with new applications being accepted in September 2010. Currently there are over 7,000 acres in active production. Hatchery-based methods, new gear, genetic improvement of stocks and advancing markets have combined to make this an attractive business for many. The University of Maryland has been a leader in the development of technology and extension educational programs to help rebuild the oyster industry for its benefits to the economy, employment and environment.