2005-09-15 / News

Farming key to returning oysters to the bay

Oysters were once so common that residents of East Greenwhich had to be enjoined by legislative act and fines in 1734 from burning them to produce lime from their shells
By Abby Anthony

Aquaculture may be able to repopulate the bay with oysters. Photo courtesy NOAA Photo Library Aquaculture may be able to repopulate the bay with oysters. Photo courtesy NOAA Photo Library The King Charles Charter of 1663 confirmed the public’s right to the free and common fisheries of Narragansett Bay, and when the Rhode Island Charter was adopted many years later, the older language was picked up and reinforced.

State ownership and management of the bay’s fisheries and shellfisheries for the public good were assured, and with the approval of the state, residents could harvest fish and shellfish up to the mean high tide line, the point at which private ownership of land begins.

In 1789, however, Samuel Thurber purchased the first oyster lease, and in 1864 new state statutes governing the leasing of sections of the bay bottom for private oyster cultivation were adopted.

Throughout the 19th and early 20th centuries, the oyster business was one of the most notable and prosperous fisheries in Narragansett Bay. The sandy-rocky bottoms of the bay’s coves and salt ponds provided good habitat for the native oysters, and, according to Rhode Island SeaGrant publications, oysters were so common that residents of East Greenwhich had to be enjoined by legislative act and fines in 1734 from burning them to produce lime from their shells.

Throughout this period many Rhode Island watermen made their livings harvesting oysters with hand tongs and oar-powered dinghys. The oyster industry was lucrative and substantial commercial operations began to grow following the Civil War, as epicures developed a taste for Narragansett Bay oysters.

At that time, native oysters were sold in the shell for between $1.25 and $1.50 per bushel. A 1914 edition of the Providence Evening Tribune reports that oyster production had reached a peak in 1911, when 15 million pounds of oysters were harvested from Narragansett Bay, and in 1912 the state leased 21,000 acres of bay bottom for oyster cultivation.

Despite the fishery’s success, cultivating oysters was, and still is, a risky business. Watermen not only had to watch out for human poachers, but natural predators could wreak havoc on their oyster beds as well. Starfish prey on oysters, and as the number of oyster leases increased, so did the number of starfish.

In the 1900s, the watermen attempted to eradicate the starfish by cutting them in half and throwing them back in the bay. Despite their efforts, the unsuspecting watermen were only successful in doubling the population of the self-regenerating predators.

OysterWars

Jamestown resident Marta Gomez-Chiarri, a shellfish pathologist and a professor of fish and animal sciences at the University of Rhode Island, attributes the end of the oyster business in Narragansett Bay in the 1950s, also known as the “Oyster Wars,” to three factors.

First, the interests of watermen and recreational boaters began to conflict. The watermen marked their oyster beds with buoys or stakes that the boaters viewed as a menace to navigation. On one occasion, boaters blocked the entrance to Narragansett Bay and — in Boston Tea Party-style — pirated the incoming boats delivering oyster seeds and dumped the seeds overboard.

Second, pollution from the Providence River was spreading throughout the bay and worsening the water quality. And third, the hurricane of 1938 dismantled all of the oyster beds and wrecked all but one commercial operation. Whatever the cause, the oyster industry closed in Narragansett Bay in 1957.

That is not the end of the oysters’ story in Narragansett Bay, however. According to GomezChiarri, who studies oyster diseases, aquaculture may be able to repopulate the bay with oysters. Oyster aquaculture began to make a comeback about six or seven years ago, but the industry’s progress has been slower in Rhode Island than in neighboring states. While Rhode Island farmers produce roughly $400,000 in oysters each year, in Connecticut aquaculture is a million-dollar industry. The growth of aquaculture has been hindered by the lengthy regulatory process and by risk, says Gomez-Chiarri.

Until recently, there was very little statistical data on the risks associated with aquaculture. Therefore, banks had difficulty assessing the risk of lending to prospective farmers and were reluctant approve loans. Several oyster farms have been very successful, however, and gourmets are beginning to recognize Narragansett Bay oysters as some of the finest tasting. Oysters grown in Point Judith Pond, for example, are sold to restaurants in New York City that proudly serve them under their trade name, Moonstone Oysters.

Oyster diseases

Despite the success of farmed oysters, wild oysters cannot thrive in Narragansett Bay. According to Gomez-Chiarri, wild oysters are threatened by infectious oyster diseases, especially one known as “dermo.”

Dermo is caused by a singlecell, microscopic parasite that is about the same size as the algae oysters feed on. The parasite is ingested by the oyster and then invades the lining of the oyster’s digestive system. The parasite kills the oyster slowly by depriving it of nutrients and proliferating in the oyster’s tissue. When the oyster dies, two or three years after being infected, millions of parasites are released into the water and infect nearby oysters, creating hot spots of infected oysters. Because farmed oysters are generally harvested when they are about 18 months old, the farmers do not suffer the full effects of dermo.

According to Gomez-Chiarri, dermo disease was first identified as the cause of oyster mortality in the Gulf of Mexico 50 years ago. Until 1990, however, dermo was restricted to the warmer waters of the Gulf of Mexico and the Chesapeake Bay in Delaware and Maryland. When Gomez-Chiarri first arrived in Rhode Island, in 1998, she began to see infected oysters in isolated spots of Narragansett Bay, but it spread rapidly and is now found throughout the bay.

Since 1998 Gomez-Chiarri has been researching how dermo affects the oysters in the bay and how the oysters respond when attacked by the parasite. Mammals, including humans, have adaptive immune response, Gomez-Chiarri explained. This means that our body learns to recognize harmful viruses, bacteria, and parasites and develops antibodies to fight those diseases. Pathologists know very little, however, about how invertebrates such as oysters fight and survive disease.

GomezChiarri says that only very recently have studies indicated that invertebrates respond to diseases very differently than mammals do. She is trying to determine why the oysters in Narragansett Bay cannot survive being infected by the dermo parasite, and she speculates that the oysters’ own immune response may actually be damaging itself.

If Gomez-Chiarri and her colleagues can determine why Narragansett Bay oysters are not resistant to dermo, they can begin to search for different varieties of oysters that are not susceptible to the disease. Right now, for example, three different types of oysters are being tested at Roger Williams University to determine if any are suited to the conditions in the bay.

Off the beaten track

Gomez-Chiarri admits that her interest in studying shellfish diseases is a little off the beaten track and attributes it to growing up in a fishing village in the northwest corner of Spain. Many fishermen in her town earned their livings making long distance trips to fish the waters of Georges Bank, Namibia, and Morroco. When international waters were established and countries closed their fishing grounds to foreign vessels in the 1980s, however, the Spanish fishing industry became more reliant on aquaculture to meet the Spanish demand for fish and shellfish.

At that time, Gomez-Chiarri was studying for her Ph.D. in immuno-pathology at the university in Madrid. Although her doctoral work focused on kidney diseases in rats and mice, GomezChiarri was awarded a post-doctoral position at Stanford University’s Hopkins Marine Station in Monterey, Calif. At the marine station, Gomez-Chiarri applied her knowledge of mammals’ immune systems to fish and began making a vaccine to fight kidney disease in trout.

Now, Gomez-Chiarri is working with an international team of pathologists on a project called the Oyster Genome Project, which is an effort to map and sequence the complete set of the oyster’s chromosomes, similar to the Human Genome Project.

Gomez-Chiarri describes her work as “detective work,” and solving the mysteries of other species’ immune systems often leads to breakthrough discoveries about our own bodies.

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