R.I. Shellfish Aquaculture Poised for Growth

By BARRY A. COSTA-PIERCE/special to ecoRI News

Experimental mussel culture in Narragansett Bay is showing great promise. Here is a seed collection rope where young mussels settle onto vertical lines in the water. (Photo courtesy of Rhode Island Sea Grant)Rhode Island could see significant growth in its shellfish aquaculture industry at a time when demand is on the rise.

U.S. consumption of mussels is skyrocketing. Americans import about 42 million pounds a year, more than 10 times what we produce. Canada’s Prince Edward Island exports most of its mussels to the United States, employing about 130 mussel farmers who farm about 11,000 acres and produce some 37 million pounds a year.

However, mussel farming in Rhode Island and southern New England could readily compete with that of Prince Edward Island, especially in terms of quality. Local waters are rich in the plankton and particles in the water — called detritus — that feed mussels and other shellfish. Our waters also are warmer, so that mussels growing here take just 10 to 12 months from seed to market, a process that takes twice as long in Canadian waters.

Bill Silkes is president and owner of American Mussel Harvesters, a shellfish processing and marketing company in North Kingstown, and owner of Salt Water Farms in the East Passage of Narragansett Bay off Aquidneck Island. Silkes is involved in a Sea Grant National Strategic Investment grant to expand mussel farming offshore. Silkes is working with a team of Rhode Island and Massachusetts fishermen, scientists and staff from the University of Rhode Island, the Marine Biological Laboratory in Woods Hole and the Coastal Resources Management Council (CRMC) on a mussel-farming project in the waters off Newport, Block Island and Massachusetts.

He said farming mussels in southern New England has the most immediate return on investment in terms of economic development for creating significant employment and economic opportunities. Silkes added that cultivation of seaweeds for “sea vegetables” is also an area of potential growth.

“We have a number of chefs that say they are interested, and we have sent out 30 pounds of samples for feedback,” he said.

Research also shows that oyster cultivation could be increased substantially in Rhode Island. Former URI graduate student Carrie Byron found that the biomass of cultured oysters could be increased 625 times current levels for Narragansett Bay and 62 times in Rhode Island’s coastal lagoons — or salt ponds — before the ecology of these ecosystems would be affected.

For Narragansett Bay, such an expansion would translate to about 218 million pounds of farmed oysters annually — an amount that is about four times the total estimated annual harvest of fish in the bay. Byron’s “socio-ecological carrying capacity” approach to aquaculture takes into consideration not only these figures and rigorous ecological modeling, but also a stakeholder process.

With the efforts of promising scientists, innovative business owners/farmers and others, Rhode Island has a great deal of opportunity for growth in sustainable aquaculture.

Barry A. Costa-Pierce is the Rhode Island Sea Grant director and professor of Fisheries and Aquaculture at the University of Rhode Island. The story appears in 41°N, a publication of Rhode Island Sea Grant and the Coastal Institute at the University of Rhode Island.

Comments

[Cynthia Fuller]

While I am certainly supportive of developing the RI market in this area, I am concerned that appropriate attention hasn't been given to the sediment quality in Narragansett Bay, where these mussels may be grown. From data on Narragansett Bay sediments that I have seen, metals, pesticides, and polycyclia aromatic hydrocarbons are a concern. These chemicals can accumulate in mussels and other mollusks/shellfish, suggesting that health risks from consumption may be present. Development of a Narragansett Bay mollusk/shellfish market absolutely needs to look at the sediment quality beforehand. Don't count on the FDA or RIDEM to protect your health; sediments and seafood quality are significantly under-regulated.

[Barry Costa-Pierce]

Cynthia has a good point. We certainly wouldn't want all of the benefits we incur from eating seafoods like mussels to be offset by intake of additional contaminants. Most mussels are however grown in the water column on ropes. Obviously the risk to consumers from eating rope-grown mussels would be from contaminants in the water column, esp. hydrocarbons; but those concentrations (and metals and pesticides too) are in trace amounts in the Bay - so low that we need the most sophisticated instruments available just to detect them.

Contamination of Bay sediments is legacy pollution, largely from pre-Clean Water Act days, from the 1800's through the mid-1900's. Modern day inputs of the chemicals Cynthia mentioned are as i stated in trace amounts, and arise mainly from non-point pollution, runoff from roads and other impervious surfaces, and thus are quite localized and tightly bound to sediments. The Bay has been stirred annually from storms, and during annual spring (and sometimes) fall turnovers that currents have penetrated to the very bottom and stirred Bay sediments into the water innumerable times over the last decades since that legacy pollution of the late 1800-to mid-1900's was added.

Thus, the risk of contamination to bottom-dwelling mussels from contaminated sediments is very low. This has been confirmed in studies elsewhere where sediment contamination was much higher than the Bay, and the findings were that, "In all cases the contaminant concentrations in mussels were well below the permissible limits for consuming seafood."

All the best

Barry