Improving Oyster Aquaculture in Rhode Island: Development and Testing of the "Rhodoyster"

Improving Oyster Aquaculture in Rhode Island: Development and Testing of the "Rhodoyster"

Summary

Oyster aquaculture is the largest segment of aquaculture in Southern New England. In Rhode Island (RI), 30 farmers generated more than $1.5 million of production in 2007. The highest risk on oyster farms is disease. The goal of this project is to stimulate the growth of the oyster aquaculture industry in southern New England by: a) developing the Rhodoyster, a disease-resistant strain well-adapted to local growing conditions, consisting of a hybrid of a local strain and a disease-resistant strain; and b) involving at least 25 of 200 oyster farmers in the RI region in evaluating the performance of disease-resistant strains. Direct participation of farmers in strain testing, combined with several outreach and extension activities including on-site training and workshops on best management practices and health management will encourage at least 11 oyster farmers in RI to adopt at least one of the following practices: 1) using more than one strain in their farms, therefore potentially avoiding catastrophic losses due to disease (increased diversification); and 2) using at least one strain that is disease-resistant and well-adapted to local conditions, leading to a 10% increase in yield. In 2008, 14 farmers in Rhode Island received seed from 3 strains, a disease-resistant strain, a local strain, and a hybrid, and were trained on how to evaluate performance. We were unable to target farmers in Massachusetts since we did not receive permission from regulators to move oyster seed across state lines. As of December 2008, data on performance was received from 5 farmers. The major findings from the 2008 summer season show that Juvenile Oyster Disease (JOD) was detected in 5 of the farms, and was responsible for significant losses in 3 of those farms. At farms experiencing mortality due to JOD, the disease- resistant strain NEHY showed significantly better performance (from 40 to 160% better) than the other 2 strains. No differences in performance where observed in farms that did not experience JOD mortality. These results show that using disease-resistant strains can lead to significant decreases in losses in case of disease outbreaks. In 2009, we will develop strategies to move seed directly from hatchery in order to address concerns from regulators and be able to target beneficiaries outside Rhode Island. Availability of research data on strain performance in a large number of farms through two growing seasons will help farmers in New England area to make wise decisions on strain choice.

Objectives/Performance Targets

By the end of this project, the development of a new strain well-suited to the RI region will be initiated. 11 of the 200 farmers in the RI area will adopt at least one of the following practices: 1) using more than one strain in their farms, therefore potentially avoiding catastrophic losses due to disease (increased diversification); and 2) using at least one strain that is disease-resistant and well-adapted to local conditions, leading to a 10% increase in yield.

Accomplishments/Milestones

• Milestone 1. 200 farmers from the RI region, as well as other stakeholders, will receive information through public meetings and mailings about the project and the results from previous testing, input about farmer’s needs will be requested. This milestone has been met. We have used different venues to let farmers and other interest groups know of our project, including contact by phone through extension specialists and the Rhode Island Aquaculture Coordinator, presentations at regional meetings (Northeast Aquaculture Conference and Exposition in Mystic, Connecticut, December 2006, and Portland, Maine, December 2008; Aquaculture 2007, San Antonio, TX, March 2007; Milford Aquaculture Seminar, New Haven, Connecticut, February 2008; and National Shellfisheries Association, Providence, Rhode Island, April 2008), a class at Roger Williams University (Shellfish Aquaculture, Spring 2007, 10 students) for people that are planning to go into the shellfish aquaculture business in Rhode Island and Massachusetts, and at two meetings of the Ocean State Aquaculture Association. We estimate that we have reached an audience composed of farmers (regionally and nationally, an estimate of 30 to 40 farmers), extension agents (including those for Connecticut, Massachusetts, and Maine), and scientists.

  Milestone 2. 50 farmers will provide input on their needs. Strains to be used in the research will be chosen based on previous research and farmer input. This milestone has been partially met. We received input from farmers in the Ocean State Aquaculture Association (25 farmers) regarding choice of strains for the project. These included resistance to Juvenile Oyster Disease and hypoxia, resistance to parasitic diseases, and good growth. Based on previous data, it was decided that the Rhodoyster would consist of a hybrid between local oysters from Green Hill Pond (RI) and the disease-resistant strain NEHY, from Rutgers University.

  Milestone 3 (revised). The Rhodoyster will be developed. Oyster seed from each strain to be tested will be produced, 20 farmers from the RI area will sign up to the research program and receive seed oysters from 3 selected strains (May – July 2008). This target was partially met. Two batches of oysters from the 3 target strains (the local Green Hill Pond, the disease-resistant NEHY, and a hybrid between the two) was produced in Spring 2008 and provided to 14 farmers in Rhode Island. We were unable to provide seed to interested farmers in Massachusetts (MA), since MA regulators did not allow importation of seed from Rhode Island due to concerns on the transfer of disease.

  Milestone 4. 15 farmers will provide data on year 1 performance. Data will be analyzed and results presented to participant farmers and other beneficiaries (new target date: November – December 2008). This objective was partially met. We have received data from 5 farmers. The major findings from the 2008 summer season show that Juvenile Oyster Disease (JOD) was detected in 5 of the farms, and was responsible for significant losses in 3 of those farms. At farms experiencing mortality due to JOD, the disease resistant strain showed significantly better performance (from 40 to 160% better) than the other 2 strains. No differences in performance where observed in farms that did not experience JOD mortality. These results show that using disease-resistant strains can lead to significant decreases in losses in case of disease outbreaks. Analysis of data on oyster size and environmental conditions at the farms confirm previous research that indicates that mortalities are highest in oysters less than 25 mm, and that early planting prevents most mortalities. At least two farmers observed mortalities due to JOD in the late fall, when water temperatures were less than 20 degrees centigrade. This is unusual, since mortalities due to JOD are usually observed in the summer, when water temperatures are above 20 degrees centigrade. These results suggest that complex and unknown environmental conditions determine if oysters are going to experience mortality. Results were presented at the Northeast Aquaculture Conference and Exposition in Portland, Maine, December 2008, and at the December meeting of the Ocean State Aquaculture Association.

  Milestone 5. Seed will be produced and 15 farmers will receive this batch of oyster seed and on-site training and assistance (new target date: May – July 2009).

  Milestone 6. 12 farmers will provide data on year 2 performance. Data will be analyzed and results presented to participant farmers and other beneficiaries (new target date: Nov – Dec 09).

  Milestone 7. 11 farmers will provide data on year 3 performance. Data will be analyzed and results presented to participant farmers and other beneficiaries. Publications will be prepared (new target date: Dec 09 – Dec 10).
  In order to achieve our goals, we are planning to request a one year no-cost extension for the 4th year (2010).

Impacts and Contributions/Outcomes

1. Farmers (about 30) were contacted through difference venues (milestone 1) and several (25) provided input and expressed interest in participating in the project.

   Strains to be used in the project were chosen based on input from farmers.

   Oysters were produced in 2008 and distributed to 14 farmers.

   Farmers (12) were trained on methods for evaluating performance and health management techniques.

   Data on performance was provided by 5 farmers.

   The major findings from the 2008 summer season show that Juvenile Oyster Disease (JOD) was detected in 5 of the farms, and was responsible for significant losses in 2 of those farms. At farms experiencing mortality due to JOD, the disease resistant strain showed significantly better performance (from 40 to 160% better) than the other 2 strains. No differences in performance where observed in farms that did not experience JOD mortality. These results show that using disease-resistant strains can lead to significant decreases in losses in case of disease outbreaks.

   Unexpected results showing mortalities due to JOD at an unusual time has led us to include protocols to track environmental conditions at the farm other than temperature, including hypoxia and pH. This will allow us to determine the influence of environmental factors on oyster mortalities due to JOD.

   These results were presented at the Northeast Aquaculture Conference and Exposition in Portland, Maine, December 2008, and at the December meeting of the Ocean State Aquaculture Association.

   At least 14 farmers are now aware of the impact of Juvenile Oyster Disease in Rhode Island farms and of some of the management techniques that prevent losses due to this disease. These include: using disease-resistant strains, planting early in the season so oysters reach sizes larger than 25 mm by the time water temperatures reach 20 degrees centigrade, and providing good flow.

   In 2009, we will develop strategies to move seed directly from hatchery in order to address concerns from regulators and be able to target beneficiaries outside Rhode Island. Our goal is to determine if JOD is also affecting farms in Massachusetts.

Collaborators: