Adaptation and integration of remote setting, selective breeding and triploid production technologies to revitalize oyster culture in Delaware Bay
Oyster production in Delaware Bay and elsewhere is a fraction of historic levels. Formerly prosperous communities have been decimated as boat works, marinas, shucking houses, and other oyster-associated industries have closed. Rural communities located in the impoverished counties of Cumberland and Salem New Jersey have lost an important source of jobs and income. This project will combine intensive hatchery culture methods with extensive grow out methods to revive production on 33,000 acres of leased oyster grounds in lower Delaware Bay, stimulating local communities. Specifically, we will combine advances in shellfish husbandry (hatchery production, remote setting), selective breeding (fast growth, disease resistance), and chromosome set manipulation (triploidy), for use in traditional extensive aquaculture operations to support the shucked oyster market. Application of these technologies has been limited to intensive aquaculture and the production of shell stock oysters for the half shell market leaving a void in supply to meet demand for shucked oysters. This demand is currently inadequately addressed by harvests from ailing oyster fisheries resulting in an increased reliance on imports from foreign markets. We will test whether or not hatchery produced triploid larvae from selectively bred oyster lines can be remotely set on shell and economically grown on bottom to market size. A key objective is to get enough oysters to survive their first year of cultivation where predation typically imposes considerable mortality. By planting hatchery-produced oysters before predators are active and by using fast growing, selectively bred triploid oysters, we believe we can overcome this problem.
Task 1: Pre-sample and prepare grounds – complete.
Task 2: Produce triploid, disease-resistant larvae and remotely set on cultch – complete.
Task 3: Deploy spatted shell – complete.
Task 4: Shell planting – complete (adequate shell was already present on site)
Task 5: Monitor growth and survival – in progress, to be completed next year
Task 6: Analyze results – to be completed next year
1) May-June 2011 – The equipment necessary for this operation was researched and purchased. The equipment includes setting tanks, water pumps, aeration pumps, immersion heaters and a wide variety of laboratory equipment including a research grade stereo microscope. During this time the site was prepped to install setting tanks and the building was refurbished supplying an office and a laboratory for the project. Equipment delivery delayed completion of the installation, but all was ready by July.
2) July 2011 – The designated oyster bottom ground on leased property in Delaware Bay was prepared to receive the spat on shell planting. The ground was sampled to determine if natural set was present. None was found and few oysters were present, but the ground contained a good shell base for receiving spat on shell. The ground was divided into two plots – one that would receive the spat on shell and the other left to capture natural set for comparison.
3) Triploid eyed larvae (i.e., mature larvae ready to metamorphose and attach to oyster shell) were received on July 30th (10 million), August 5th (9 million), and August 16th (4 million). These dates were later than originally planned due to construction delays and subsequent hatchery delays but corresponded to the natural period of oyster recruitment in Delaware Bay. In total, approximately 23 million eyed larvae from the NJ AIC for use in our project.
4) Our plan was to set larvae as soon as possible in May or June to extend the initial growing season so that oysters would get a head start on reaching predator size refuges and also reach market size earlier. As previously stated, delays in construction and hatchery production beyond our control did not permit this early setting of oyster larvae. Nevertheless, we did successfully set larvae, but it occurred during the period of natural recruitment in Delaware Bay. Hence, the first planting was not conducted until August 8th, instead of the proposed timeframe of May-June. The second planting was on August 15th and the third on August 26, 2011. The third planting was performed one day before hurricane Irene hit the coast of South Jersey. The effects of this storm caused adverse salinity levels in the Delaware Bay due to fresh water infiltration. This dilemma led to many other detrimental environmental conditions possibly affecting bivalves and endangering the success of our newly planted spat on shell. Our science advisor from Rutgers, David Bushek, was able to deploy a salinity recorder directly over our shell plant within a week of the storms passing and determined that salinity levels recovered quickly although remained on the low side of average levels through September as freshwater worked its way down the bay.
5) Regardless of the aforementioned problems, our set rate on average was greater than or equal to 14.5%. Our mortality/survival sampling conducted in November 2011 indicated a 50% survival rate and a growth rate of 16mm on average which is five times larger than when we planted the spat in August 2011. According to historical data from scientists at various Rutgers labs which we have been working with our setting results have been above average proving the success and the need for projects such as this. Furthermore, despite the impacts of Hurricane Irene which was followed by record precipation from Tropical Storm Lee, we saw growth rates of spat well within average levels. We suspect that growth would have been well above average had these storms not impacted conditions in the bay.
Impacts and Contributions/Outcomes
6) Due to the delay in setting and planting we are proposing that a new stock be planted in 2012 during May and June to verify that such efforts would achieve even greater growth and survival proving the benefits of remote setting and planting of triploid oyster spat on shell. This will revitalize the vast acreage of leased bottom increasing economical demand for shucked oysters to restore this dying component of the domestic oyster industry and increase job growth in our community and country.
Rutgers Haskin Shellfish Research Laboratory
6959 Miller Avenue
Port Norris, NJ 08349
Office Phone: 8567850074