Field Notes
an inside look at the science and stories behind CSLI
Oyster Restoration Program Finishes Its 2026 Season
Contributed by Sam Clarke, Volunteer
Coastal Steward Long Island’s 2026 Oyster Restoration Program came to a close on October 31st, ending a 23 week growing season that started on May 23, 2026. Every two weeks volunteers, who contributed 276 hours of their time over the course of the season, worked together to clean and measure the oysters so that their health and growth could be monitored. Cleaning the oysters is vital because too much algae and other organisms can hinder their growth. To prevent this from happening, volunteers took the oyster bags from their crates and used a power washer to remove the growing organisms. Oysters from two bags were repeatedly measured to record growth and mortality.
For this season, the mortality rate of the oysters was 40%. This could have been the result of many factors, but the most likely culprit were the summertime temperatures which were very high this year. The resulting early season high water temperatures led to a decline in the oysters’ stress tolerance. The constant high temperatures throughout the summer also reduced the water’s oxygen-holding abilities. All of this combined led to an environment of low oxygen and high stress throughout the summer. Despite the high mortality rates, the surviving shellfish had a 104% increase in individual shell size, averaging 60 mm in length by the end of the five-month long season.
vessel
At the close of the season, volunteers distributed the surviving oysters across Mt Sinai and Port Jefferson Harbors to reefs that the program has been restoring over the years. On October 17th, volunteers deposited 20,000 oysters in Mt Sinai Harbor on the bottle cap reef. Two weeks later, volunteers repeated this in Port Jefferson Harbor. 30,000 oysters were deposited on the east side of the harbor opposite of the National Grid stacks with another 30,000 placed on the west side slightly north of the National Grid stacks. Longtime CSLI supporter, Town of Brookhaven Councilmember Jane Bonner, was our very special guest volunteer for this season-ending event.
Oysters play a crucial role in coastal ecosystems. They are filter feeders, removing excess nutrients from the water and improving water quality. The oysters that were released will more than triple daily filtration capabilities in those waters. The reefs that they form also serve as habitat for various species of fish and crustaceans and protect against storms and erosion. By restoring the oyster populations, CSLI continues to promote balance in our coastal ecosystems. Coastal Steward Long Island thanks everyone who made the 2026 season a success, and looks forward to continued progress in 2027.