An Improved Tidal-Powered Upwelling Shellfish Nursery System for Vineyard Aquaculturists
Seed oysters cultured in the shellfish nursery system.
In this project five innovative tidal powered upwelling shellfish nurseries were constructed and operated by a group of retrained fishermen looking to shellfish aquaculture as an alternative occupation. The project uniquely met the goals of the NFWF "Challenge Grants for Environmentally Sound Aquaculture" program. The project provided for the construction and operation of environmentally sound tidal powered shellfish nurseries to support a local, sustainable shellfish aquaculture industry on Martha’s Vineyard. The project built upon already successful efforts to provide alternative employment opportunities for fishermen displaced by federal fishing closures. The project supported efforts to reduce fishing pressures on depleted natural stocks and degraded habitats, thereby, hastening the time to recovery.
As the overfishing crisis on Georges Bank makes painfully clear, demand for fish resources has outstripped the natural supply and there can be no expansion of the traditional fishing industry, only further contraction. Growth in the fishing industry will only occur with an increase in the supply of the resource. In order to survive, the fishing industry must evolve into an aquaculture industry. Exploitation can no longer occur without concurrent efforts to renew the resource.
Fishing area closures were inevitable in light of the severe decline of the Northeast's traditional groundfish and scallop stocks. These closures have resulted in real economic hardship for fishermen on Martha’s Vineyard. On an island that already suffers from one of the highest unemployment rates in the state of Massachusetts, newly unemployed fishermen find scarce year round economic opportunities. Further, fishing is as much a lifestyle as it is an occupation. Georges Bank closures have resulted not merely in the loss of jobs, but for many, the end of a way of life. Those fishermen who have spent most of their lives working independently on the open ocean are not likely to succeed, much less be satisfied in a structured nine to five service job in the Island's mostly tourist oriented economy. "Once a fisherman always a fisherman" may explain why many who have quit Georges Bank are now trying to squeak out a living exploiting very limited inshore stocks of shellfish. The movement of these offshore fishermen into inshore waters compounds the number of fishermen impacted by the Georges Bank fishing crisis as these new inshore fishermen compete with existing inshore fishermen. The social and economic impacts of the Georges Bank closures now also spread to the inshore fishing community as their traditional stocks are now exploited by the displaced offshore fishermen. Public aquaculture efforts aimed at stock enhancement by the Martha’s Vineyard Shellfish Group, no matter how successful, are not extensive enough to adequately supply the needs of all the inshore commercial fishermen.
Private aquaculture ventures can maximize the shellfish production of inshore waters, increase exploitable stocks and provide alternative employment opportunities for fishermen now competing for limited public shellfish stocks. Aquaculture appears to be an ideal occupational alternative for displaced fishermen finding ready application of their existing water based skills and producing the same seafood products that they are experienced in handling and marketing.
Shellfish seed availability, especially larger field plant size, remains a serious impediment to the development of shellfish aquaculture for the new fishermen/aquaculturists in Massachusetts. Growers with access to a nursery system can purchase less expensive and more easily available shellfish seed to stock their shellfish farms.. Waterfront sites for conventional onshore nursery systems in Massachusetts are, however, cost prohibitive if not also prohibited by zoning
Since its introduction in 1988 by William Mook of Mook Sea Farms in Maine, the tidal powered upweller nursery system has proved itself a viable alternative to shore based nursery systems for shellfish aquaculture. As described and explained in the National Coastal Resources Research and Development Institute's booklet "Construction and Operations Manual for a Tidal Powered Upwelling Nursery System" (R. Baldwin, et al., April 1995), the tidal upweller does not require expensive land, pumps, electricity, or algae and can be moved if changes in water quality so require.
Working from the Mook tidal upweller plans, Jack Blake, commercial fisherman and aquaculturist, redesigned, constructed, and tested a tidal upweller shellfish nursery in Katama Bay in Edgartown in 1998. Mr. Blake redesigned the Mook upweller to increase both its flow and capacity. In his upweller, Blake has done away with outlet holes and thereby reduced much of the constriction to flow through the upweller . Capacity has been increased from Mook's sixteen bins to seventy-two. The Blake upweller has a capacity to grow four times the amount of 5 mm quahog seed as the Mook nursery. The amount of 9 mm oyster seed that can be grown in the Blake system is six times the amount of 9 mm quahog seed recommended for the Mook upweller.
In this project NFWF provided funds for the materials to construct five tidal powered upweller nursery systems after the design of the Blake prototype to be used by Island fishermen/growers. Jack Blake and four other commercial fishermen (Tom Berry, Scott Castro, Ray Gailey and Roy Scheffer), all graduates of the Martha's Vineyard Aquaculture Training Program contributed their labor to construct and operate the floating shellfish nurseries. Paul Bagnall and Warren Gaines of the Edgartown Shellfish Department assisted with the construction of Roy Scheffer’s nursery and in return used the unit for part of the growing season to culture shellfish seed for public stock enhancement.
Project Goals and Accomplishments
--The project provided for the production and distribution by the MVSG Hatchery of over 1 million seed oysters and 0.5 million seed quahogs to the growers.
--The new shellfish nurseries proved to be an effective new tool for the five growers who constructed and operated them. The nurseries provided a means to successfully and efficiently culture 200,000 seed oysters and quahogs for their shellfish farms in 1999 and 2000. The nurseries provided the means to grow the seed at an accelerated rate resulting in the growers’ oysters reaching market size before three years and thus avoiding losses from SSO disease which has caused mortality in three year old oysters. The ability to lessen losses from disease is crucial to the success of the growers’ new aquaculture ventures.
--Use of one of the new nurseries by the Edgartown Shellfish Department provided for improved survival of quahog seed cultured for public stock enhancement.
--Five new tidal-powered shellfish nurseries were constructed and operated over the course of two growing seasons in 1999 and 2000. Excellent growth and survival of the seed shellfish was documented over the course of the project proving the effectiveness of the new nursery systems.
-- Operation of the nursery systems in 1999, led to modifications and improvements in the original design that were tested and demonstrated in 2000.
-- In 1999 over one half million seed oysters were cultured in Katama Bay as a result of this project. The number rose to over a million oysters with the addition of more shellfish to the growers’ sites in 2000. According to calculations by Dr. Michael Rice of the University of Rhode Island, one million rapidly growing cultured oysters eliminates the nitrogen pollution from about 270 people living in the watershed!
--Reports of the findings of this project have been presented at four public aquaculture forums. An abstract of the project has been published in the Journal of Shellfish Research. By year’s end, information and design plans for the new shellfish nursery are expected to be posted on three internet websites.