Scientists restore collapsed clam population and water quality in Shinnecock Bay

Scientists from Stony Brook University’s School of Marine and Atmospheric Sciences (SoMAS) announced the culmination of a decade of science in a paper published in Frontiers in Marine Science, which describes a new restoration approach used in Shinnecock Bay that has led to a 1,700% increase in landings and densities of hard clams in that estuary, along with the expansion of seagrass meadows and the end of harmful tidal flats coffee. This result returns Shinnecock Bay to its 20th century shellfishing glory and can serve as a shining example of a process to restore other estuaries around the country and the world.

Long Island hard oysters were once the largest fishery in New York State history. In the 1970s, two out of three clams eaten in the United States came from Long Island. Since then, the fishery had collapsed by more than 99% and, despite more than four decades of recovery efforts, the fishery has never recovered, until now.

A decade ago, Shinnecock Bay was a seemingly irreversible estuary. By 2011, hard clam landings, historically the dominant filter feeding bivalves in New York estuaries, had collapsed. As a key organism, this loss caused a trickle-down effect throughout the estuary, as most of the seagrass in the entire system was lost and damaging, intense brown tides were occurring every year. And while the situation was emblematic of estuaries on Long Island and around the world, the state of the system seemed particularly dire.

“99.5%. Sometimes the numbers are used as hyperbole, but that’s how much hard clam landings had declined from the 1970s to 2011 in Shinnecock Bay,” said Stony Brook University Chair and Professor of Marine Sciences Chris Gobler, Ph. D., and lead author of the study. “These bivalves are known as ecosystem engineers as their ability to filter feed can remove algae, improve water clarity and have downstream effects on habitats such as seagrass meadows that need clean water to survive. thrived. When an estuary experiences a loss of filter-feeding bivalves, the effects on the entire ecosystem can be profound. We knew that a key to the recovery of this ecosystem would be restoring the clam population in Shinnecock Bay.”

The Stony Brook scientists also knew that the task of restoring the hardy clams would not be easy, as over 40 years of previous efforts had been largely unsuccessful. A new approach, based on science and tailored to the specific nature of Shinnecock Bay, was needed.

The road to restoration

Working with his Marine Science professor, Brad Peterson, Gobler began an entire ecosystem study of Shinnecock Bay in 2004 to understand the factors that limit clam and seagrass populations and the drivers of poor water quality. What they discovered was a recruitment-limited population of hardy clams, with adults so rare that the likelihood of successful reproduction for these egg-laying individuals was extremely low. This discovery, in part, led to the primary approach of what became the central effort of the Shinnecock Bay Restoration Program: the creation of protected hardy clam sites, regions where hardy-grown clams would be able to maximize production of their reproductive, circulating their eggs. throughout the bay.

To optimize the creation of spawning sanctuaries, scientists needed three important components: Financial support to execute the plan, cooperation from regional and mammal officials, and careful science to identify ideal locations for sanctuaries and to monitor progress. Fortunately, all these ingredients came together.

Nine years of support for the project was generously provided by the Laurie Landeau Foundation with additional support from the New York Department of Environmental Conservation. Southampton city trustees worked with Stony Brook University scientists and the Southampton City Baymen’s Association to identify regions that would be “no-go” areas where clam harvesting was prohibited, so that farmed clams to be able to repopulate the bay without poaching. Finally, the scientists identified regions that would maximize the ability of adult clams to reproduce and retain their spawn within the bay.

“The spawning sanctuaries reached gold zones. They were far enough from the ocean inlets so that the eggs or larvae would not be washed into the Atlantic Ocean, but not so far from the clean ocean water that the adult clams would perish due to of poor water quality,” Professor Gobler said. “Being able to use science to identify the ideal location for finding spawning grounds was a key to the success of this program.”

Turning the tide

The success of the restoration did not happen overnight. Over a five-year period (2012-2017), more than 3 million strong adult clams were planted in spawning grounds in Shinnecock Bay, and given that clams take several years to grow to harvestable size, population recovery is go. to take time. But over time, the density of hard clams throughout Shinnecock Bay increased, as did the harvest, and in both cases, those increases were mostly among small clams, the exact size of clams that would be expected. from the egg sanctuaries.

In addition, the scientists developed a new DNA-based method to track spawning of hard clams and demonstrated that they were progressively transported from the western part of the Gulf to the eastern half of the Gulf, where densities increased disproportionately. The accompanying increase in both clam density and clam harvests were not fully anticipated by scientists.

“The results of this restoration are a win-win for the environment and the economy,” said Mike Doall, co-author and Associate Director of Shellfish Restoration and Aquaculture within SoMAS. “Not only has the health of the ecosystem recovered, but it has helped revive a once-thriving robust oyster fishery, benefiting the livelihoods of baymen and restoring an important aspect of Long Island’s maritime history.”

According to Professor Gobler and co-authors, brown tides in New York have contributed to the collapse of bivalve populations and the decline of seagrass meadows, and have occurred more frequently and more intensely in Shinnecock Bay than anywhere else in the world. But as clams were planted and clam populations expanded, brown tides progressively diminished and then disappeared from Shinnecock Bay, with the system being disaster-free for six consecutive years despite their annual appearance in The neighboring Great South Bay. There has never been a six-year period without brown tides in Shinnecock Bay dating back to their first appearance in 1985.

“Successful restoration of Shinnecock Bay has recently led to global distinction for this estuary,” says Ellen Pikitch, Ph.D., a co-author and SoMAS Endowed Professor of Ocean Conservation Science.

In June, the bay was named a point of hope by the international organization Mission Blue.

“This honor signals that Shinnecock Bay is a beacon of hope—not just for Long Island—but for areas around the world,” adds Pikitch. “We have demonstrated that sustained, science-led research, restoration and monitoring can undo the damage that has been done, and this is reason for optimism that similar programs elsewhere will also yield positive results.”

The research team says it’s hopeful that Shinnecock Bay’s success is a model that will be replicated across Long Island and beyond. For example, in 2017, NYSDEC established the Long Island Shellfish Restoration Program, which replicated the approach in Shinnecock Bay, creating hardshell shellfish sanctuaries at four other locations across Long Island.