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Volume 2 | Issue 1 | Page 82-88 | Jan 2011
Hard Clams, Hard Lessons: The Shellfish Renaissance
R. Gurian
Local baymen work with The Nature Conservancy to stock adult clams in sanctuaries in the Great South Bay.

When overfishing led to the collapse of what was once the most important hard clam (a.k.a. northern quahog) fishery in the United States, a way of life and more than 6,000 jobs were lost. Worse, harmful growths of brown tide algae became chronic in the absence of the clam’s water filtration services, seriously altering the ecosystem of Great South Bay, New York, to the detriment of fish, wildlife, and people. It is an all too familiar story of resource exploitation. However, a creative land deal by The Nature Conservancy and dedicated project partners has turned the corner on this 35-year decline of hard clams in Great South Bay. This project is an example of how recent scientific appreciation for the ecosystem services provided by shellfish has expanded support for restoring native shellfish in estuaries around the United States, as well as the rationale and approaches used for such rehabilitation efforts. Today, through concerted efforts, creative partnerships, and unique opportunities, hard clams have an opportunity to recover to the level of a self-sustaining population in Great South Bay.

History of the Hard Clam

The humble hard clam plays a vital role in coastal ecosystems ranging from Florida to Maine. Hard clams feed by filtering tiny suspended particles of phytoplankton from the ocean. Each clam filters up to 3.8 liters of water per hour, regulating water clarity, cycling nutrients,1 and making areas more resistant to harmful algal blooms.2,3 Water clarity affects light transmission at depth, which is an important determinant for where seagrass, an essential fish habitat, can grow. Many species of fish, waterfowl, and macroinvertebrates also feed directly on clams.

The shallow, protected estuarine waters and sandy sediments of the 24,300-hectare Great South Bay are ideal shellfish habitat. Shellfish have historically been important in the culture and economy of Great South Bay communities. Oysters and clams provided a reliable protein source for Native Americans, who traded jewelry called wampum that they made from clam shells. From the late 1700s onward, the Great South Bay oysters, known as Blue Points, were highly valued in the markets of Europe and nearby New York City. (The streets of Sayville, a community at the heart of the bay, were paved with shells. Even today it is common to find Sayville residents who have at least one family member or friend who at one time made a living harvesting shellfish from the briny waters of the bay.) The bay’s oysters supported 25 oyster-packing houses in the late 1800s. A government study of the bay in 1888 valued the oyster industry at $127,000. Clamming was little less than half that size.

By the 1950s, oyster fishing had collapsed. The combination of overfishing, habitat destruction, water quality impairments, changes to barrier island inlets, and the unintentional introduction of oyster diseases left the shellfish functionally extinct. Clams followed soon afterward. Dating to colonial times, three townships—Babylon, Islip, and Brookhaven—have owned and managed the submerged lands in Great South Bay. (The exception is the approximately 22 percent of submerged lands in central Great South Bay that, until recently, were privately owned by the Bluepoints Company.) The hard clam fishery peaked in the 1970s—when over half of the clams eaten in the United States were harvested from Great South Bay—and the town governments failed to manage the harvest sustainably. When clams were depleted from certified shellfishing areas, the disproportionally greater abundance of clams in uncertified areas created what shellfish managers called an “attractive nuisance.” As a consequence, hard clams in many of the uncertified areas, which had the potential to serve as reproductive refuge, were intentionally removed.

Between 1976 and 1984 Great South Bay saw an 80 percent decline in clam landings and the loss of thousands of shellfishing-related jobs. Unlike when the oyster fishery collapsed, there were no other large, long-lived, abundant suspension-feeding (i.e., filtering) bivalves to take up the ecological role of hard clams as they declined. This was particularly problematic because, at the same time, the algal growth–inducing nutrient loads from residential septic systems, atmospheric nitrogen deposition, and fertilizer use were on the rise in much of the Great South Bay watershed.

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C. LoBue
Recruitment is measured through large-scale shellfish surveys. Here, Nature Conservancy staff sort through sediments in search of newly settled juvenile clams.

In 1985, Great South Bay experienced its first recorded bloom of Aureococcus anophagefferens, commonly known as brown tide. These tiny algae, which can occur at densities over one million cells per milliliter, turn water brown, shade seagrass, are poor food for hard clams, and are even toxic to some shellfish.4-6 Since 1985 brown tide has chronically reappeared in Great South Bay, altering the bay’s ecology and creating an environment that is no longer as hospitable to hard clams and other shellfish as it once was. Studies suggest that a healthy hard clam population in Great South Bay might have made the area more resistant to the onset of these blooms.2

Despite the rapid decline in the abundance of clams, the towns imposed no significant changes to hard clam harvest management. By the mid-1990s the resource was no longer commercially viable, and in most of the bay harvest rates declined. Although harvest pressure decreased, the clams showed no signs of recovery, even when there were several consecutive years without brown tide. Local governments tried various fishery enhancement strategies, including the construction of a municipal shellfish hatchery in Islip, without success. Commercial hard clam landings from Great South Bay stabilized at about one percent of their peak.

Return of the Hard Clam

In 2002 The Nature Conservancy on Long Island acquired Bluepoints Company’s title to approximately 5,420 contiguous hectares of submerged lands in Great South Bay, forever ending the era of large-scale mechanical shellfish harvesting in the central section of the bay. Specific plans for the use of the property were not developed in advance of the purchase; however the stated goal of the acquisition was to improve and protect the health of the estuary while providing appropriate access for valued human activities. Recognizing the unique opportunity presented by the acquisition, The Nature Conservancy developed an advisory council consisting of local, state, and federal resource managers, experts, and stakeholders such as shellfish harvesters. The council held its first meeting at a public forum. The 100 attendees expressed a range of desired outcomes, including restoring commercial resource harvesting and creating a marine wilderness area. The overriding sentiment was a lament for what had been lost and a desire to see the health of the bay improved.

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A. Thorp
One of the last remaining Great South Bay clam tongers works the waters of the western bay.

One of the first tasks was to assess the condition of the newly acquired property, which was largely unknown because such information was deemed proprietary by the Bluepoints Company. Baseline shellfish surveys in 2004 confirmed the worst: the area was largely devoid of shellfish, a grim testament to the efficiency of mechanical shellfish harvesting. Low densities of clams elsewhere in the bay made the chance of repopulation unlikely. Upon learning this information, the shellfishers on the advisory council were the strongest advocates for using the property for on-the-ground restoration, in hopes of improving conditions in the whole bay. The council set a goal to restore clams for ecosystem health and sustainable harvest by 2020. For the first time, there was a baywide objective, a large piece of property to experiment with alternative management and restoration approaches, a forum in which key players could interact, and a mechanism for combining private and public funds from all levels of government.

No single strategy was considered the best approach to achieve the council’s collective objective. In fact, in addition to input sought from experts in shellfish biology, estuarine ecology, phytoplankton biology, water quality, and fisheries management, there was no shortage of advice offered by harbor masters, boat owners, fishers, beachcombers, and community residents. Ideas ranged from simply studying the issue for another decade to altering flushing in the bay through expansive engineering of barrier island inlets.

In the 12 months after the council’s first meetings, thoughtful interpretation of the collected information pinpointed four areas for simultaneous action: (1) understanding and better managing nutrient loads; (2) mitigating impacts of predation during stock rebuilding; (3) addressing recruitment limitation by increasing the effective spawning potential of the clam population; and (4) updating harvest management approaches to avoid future overfishing.

Between 2004 and 2010 more than four million adult clams were relocated from Connecticut and other parts of Long Island to central Great South Bay. These clams were stocked in high densities in a network of 60 relatively small (approximately 0.4-hectare) areas, called spawner sanctuaries, within the boundaries of The Nature Conservancy preserve where shellfishing was banned.

Conditions for spawning in Great South Bay varied between 2005 and 2009 but showed steady improvement in baseline stocks, with 2006 and 2007 being the best years. Adjusting for post-stocking natural mortality, just less than one million stocked adult clams contributed to spawning in 2006, and closer to two million stocked clams spawned in 2007. Based on the project’s surveys, this added approximately 18 percent to the total number of reproductive adults in central Great South Bay for the 2007 spawning season. Since fertilization success of the sparse naturally occurring clams was predicted to be much lower than that of the high-density transplanted clams, it is thought that the spawner sanctuaries increased reproductive output by much more than 18 percent.

Then, in 2008, surveys showed a 4,000 percent increase (from a 2006 baseline) in the number of juvenile clams in central Great South Bay, suggesting that stocks had finally reached a take-off point. Numbers of the then one-year-old clams, averaging 10.5 millimeters along the shell, were estimated at 320 million, covering approximately 2,000 hectares at densities of greater than five clams per square meter, making this the largest recruitment event in over 15 years. By design, it is not possible to distinguish between juvenile clams spawned from naturally occurring adults and those spawned by stocked adults. However, based on the predicted transport direction of the clam larvae, the settlement locations of juvenile clams are consistent with most of the clams originating at the spawner sanctuaries on The Nature Conservancy property.

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OTG_Clams_Figure3b.jpg
Richard Morin/Solutions; Chris Clapp; data collected by TNC; surveys by the towns of Islip, Babylon, and Brookhaven
Shellfish surveys have detected increased recruitment of juvenile clams in proximity to spawner sanctuaries established on The Nature Conservancy's property in central Great South Bay, New York.

These initial signs of increased recruitment of juvenile clams have promoted a sense of hope and have rejuvenated community enthusiasm for returning Great South Bay to a vibrant and productive estuary that supports recreational and economic opportunities associated with shellfish. The surveys demonstrated that Great South Bay is still capable of producing juvenile clams and that restoration of relatively small protected areas can result in ecological benefits well outside their boundaries. There has been further progress since 2006, including the U.S. Environmental Protection Agency designating the bay as a “no vessel discharge zone”; adoption of the first coordinated baywide changes to hard clam fishery management codes; passage of the first ever harvest restrictions on the oyster toadfish, aimed at restoring a balance of shellfish predators; and the official listing of the bay by the EPA and New York State as nutrient impaired.

Despite these encouraging public policy shifts, several challenges lie ahead. For example, the most severe brown tide on record engulfed the entire estuary in 2008–2009, curtailing spawning of adult clams and reducing the survival and growth of the strong 2007 cohort. Although conditions in 2010 improved, the restoration project anticipates that periodic blooms will be a constant hurdle. Notwithstanding initial support from the commercial fishing community, realization that commercialization of the hard clam resource will be managed to assure long-term sustainability has resulted in local controversy and heated public discourse that is testing the locally elected decision makers. Plans to devise and adopt harvest management plans in all three townships—Babylon, Brookhaven, and Islip—that can achieve the goals of rebuilding the shellfish population, reaching long-term sustainability, and meeting the needs of all constituents will certainly be a challenge. Additionally, financial support, particularly for large-scale water quality improvement projects, has become more difficult to secure. These challenges are, however, not unique to Great South Bay, and solutions found here will certainly be transferable to other estuaries.

Hope for the Future

For over a century, each generation along the shores of Great South Bay has inherited less and less of the immense natural resources that the estuary once provided. As recently as 2004, many believed that the bay’s shellfish were lost forever, another casualty of progress and development. Early results from this Nature Conservancy project indicate that, although it will be difficult and will likely take more than a decade, the return of the Great South Bay hard clam is in fact within reach.

Spawner sanctuaries need to be expanded beyond the boundaries of The Nature Conservancy’s preserve. Changes to harvest management in the public fishing grounds will also be required, to prevent overharvest in the future. In the wake of the recurrence of brown tide in 2008, ensuring improved water quality must become part of the public debate. Elected community leaders are becoming more aware that restoration of Great South Bay is strongly connected to the social and economic well-being of their constituents. It is this inherent relationship between people and the estuary that will drive the motivation, commitment, and patience needed for this project to come to a successful end.

A March 2009 letter to The Nature Conservancy from a Sayville marina owner, Mark DeAnglis, conveyed the renewed promise felt by communities around the bay: "The most important thing you have provided is hope. For years the only reports of the health of Great South Bay dealt with its decline. Stories of how the bay supported the livelihood of thousands of baymen and their families were a thing of the past. Fish stocks, eelgrass beds, water quality and clarity were all on the decline. The bay’s reputation was as a dead estuary; now the stories out of the bay are of increasing clam stocks, of better water clarity, and of a renewed recreational sector. Due to your efforts, people are once again talking of the bay as having the possibility of rehabilitation, and of a return to the health of years past. Of course this is only the beginning, but people feel that for the first time in many years, things are improving, that we are on the right track, that there is light at the end of the tunnel."

References

  1. Dame, RF. Ecology of Marine Bivalves: An Ecosystem Approach (CRC Press, New York, 1996).
  2. Cerrato, RM, Caron, DA, Lonsdale, DJ, Rose, JM & Schaffner, RA. An experimental approach to examine the effect of the northern quahog Mercenaria mercenaria on the development of blooms of the brown tide alga, Aureococcus anophagefferens. Marine Ecology Progress Series 281, 93–108 (2004).
  3. Gobler, CJ, Lonsdale, DJ & Boyer, GL. A review of the causes, effects, and potential management of harmful brown tideblooms caused by Aureococcus anophagefferens (Hargraves et Sieburth). Estuaries 28, 726–749 (2005).
  4. Cosper, EM et al. Recurrent and persistent brown tide blooms perturb coastal marine ecosystem. Estuaries 10, 284-290 (1987).
  5. Lonsdale et al. Influence of suspension-feeding bivalves on the pelagic food webs of shallow, coastal embayments. Aquatic Biology 6, 263–279 (2009).
  6. Gainey, Jr., LF & Shumway, SE. The physiological effect of Aureococcus anophagefferens (“brown tide”) on the lateral cilia of bivalve mollusks. Biological Bulletin 181, 298–306 (1991).
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