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. In 2009, 10 farmers received seed another batch of seed from the 3 strains. As of December 2009, data on performance for each of the year classes was received from 7 farmers. The major findings from the evaluation of the performance of the 2008 year class at the end of the 2009 season (oysters were 18 months old), is that seed performance was driven by survival in the 2 farms that experienced disease outbreaks during the summer and fall of 2008, with the disease-resistant strain NEH showing significantly higher survival (30 – 36% compared to 9 – 19% in GHP and HYB) and performance (153 – 198% compared to 100% for GHP). No significant differences in performance between the strains were seen in farms that did not experience disease pressure. The hybrid strain between the disease-resistant strain NEH and the local stock GHP did not show hybrid vigor. These results show that using disease-resistant strains can lead to significant decreases in losses and significantly higher performance in case of disease outbreaks, while performance is similar to other strains in absence of disease pressure. Based on farmer input, we will use survivors of the disease resistant strain NEH and the local GHP as broodstock, leading to the creation of two different strains adapted to the local conditions in 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

Performance target. 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 and national meetings, as well as meetings of the Ocean State Aquaculture Association.
  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. Clinical signs of JOD were observed at all sites, but only caused mortalities at 3 of the farms, suggesting 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). This target was partially met. Ten farmers were interested and participated in the project.
  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). This objective was partially met. As of December 2009, we received data from 6 farmers. Data from 4 of the farms was of high quality and provided a wealth of information on the effect of genetics and environment on strain performance (Fig 1). The major findings from the evaluation of the performance of the 2008 year class at the end of the 2009 season (oysters were 18 months old), is that seed performance was driven by survival in the 2 farms that experienced disease outbreaks during the summer and fall of 2008, with the disease-resistant strain NEH showing significantly higher survival (30 – 36% compared to 9 – 19% for HYB and GHP, Table 1) and performance (153 – 198% compared to 100 for GHP). At the end of the 18 month trial period, more oysters of the disease-resistant NEH strain had achieved market size compared to the other two strains, resulting in this strain outperforming the others at the 4 farms for which we obtained more detailed data (Table 1). The hybrid strain between the disease-resistant strain NEH and the local stock GHP did not show hybrid vigor. These results confirm that using disease-resistant strains can lead to significant decreases in losses and significantly higher performance in case of disease outbreaks, while performance is similar to other strains in absence of disease pressure. In a meeting with the Ocean State Aquaculture Association in early 2010, several farmers were impressed by the performance of the disease resistant strain and demonstrated interest in obtaining seed from the survivors from the tested lines.
  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). We have collected broodstock from the survivors of the disease outbreaks experienced in two of the farms, and will be spawning this broodstock during the Spring of 2010. Since hybrid vigor was not observed, we are focusing on the disease-resistant line and the local line. Seed from the two strains will be provided to at least 15 farmers. We will also contact regional hatcheries to see if they are interested in using this broodstock in future spawns.
  In order to achieve our goals, we requested a one year no-cost extension for the 4th year (2010).

• Table 1. Performance of oysters strains at 4 farms at 18 months of age
• Figure 1. Changes in volume at 4 farms 2008 – 2009

Impacts and Contributions/Outcomes

• 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 2009 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 in 2008 and 6 farmers in 2009.
  Results were presented at several regional and national meetings and trade shows, including the Northeast Aquaculture Conference and Exposition in Mystic, Connecticut, December 2006, and Portland, Maine, December 2008; Aquaculture 2007 and Aquaculture 2010, the Milford Aquaculture Seminar, New Haven, Connecticut, February 2008, 2009 and 2010; National Shellfisheries Association, Providence, RI, 2008 and Savannah, GA, 2009), the WERA099 Shellfish Genetics and Broodstock Management meetings in 2008, 2009, and 2010, 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 four meetings of the Ocean State Aquaculture Association (latest one on Feb 2010). We estimate that we have reached an audience composed of farmers (regionally and nationally, an estimate of 30 to 40 farmers), extension agents (about 7, including those for Connecticut, Massachusetts, and Maine), and scientists (more than 100). .
  At least 14 farmers are now aware of the impact of diseases such as Juvenile Oyster Disease, MSX and Dermo in Rhode Island farms and of key 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 2010, based on the input from the growers, we will use broodstock from the survivors of the disease outbreaks experienced in two of the farms participating in the project to create 2 lines well adapted to the environmental and disease pressure conditions experienced in this area.
  The East Coast Shellfish Growers Association (http://www.ecsga.org/), with represents more than 1000 farmers from Maine to Florida, considers disease one of the major problems for the industry and has started lobbying for the creation of an ARS Center in Shellfish Genetics and Breeding, with the support of a consortium of Universities in the East Coast of the US, including the two universities participating in this project (University of Rhode Island and Roger Williams University). This breeding center will provide the means to continue and enhance this project.

Collaborators: