This project seeks to determine the growth potential of the eastern oyster cultured in a coke bottle upweller system. In order to do this, small juvenile oysters (less than 1mm) will be put away at different population densities in bottle upwellers. They will be fed increasing amounts of algae every day. After 7-9 days, they will be individually evaluated and percentage growth will be calculated. The juvenile oysters will also be inspected for overall health and condition. We will determine what the ideal and practical stocking densities are. The ideal density will be the density which produces the highest percent growth. The practical density will be the density of which they produce reasonably good growth with a good health assessment and supports increasing production.
If we can prove that this system produces healthy oysters with good growth, it is likely that we as well as other hatcheries will, in the future expand and build more bottle upwellers. A potential of one million plus small oysters could occupy one bottle unit. If this is the case, the increase in oyster population capacity would be tremendous given that this system is space efficient.
As more fishermen turn to aquacultured seed to support or supplement their farms, the demand for aquacultured oyster seed has increased in recent years. Currently we use downwellers that occupy a large footprint and require a high labor demand for the small populations that they can support. As the demand for seed has increased, the ability to meet this demand is difficult because of the current spatial allowances and labor force in hatcheries. As a result, new technology is being used to maximize production, while using the same spatial allowances and labor force.
The purpose of this project was to build a coke bottle upweller system that is space efficient, labor saving and maximizes the growth potential of oyster seed. If this system proves to be efficient then we will be able to house more animals, thus increasing the overall production. With increased production we will be able to provide more healthy and fast growing seed to farmers, allowing for sustainable aquaculture in the northeast.
The research portion of this project has been delayed due to the availability of the ideal size of oyster seed. Research will resume in the spring when production of oysters resumes.
However, before deployment, we discovered several designs flaws with the coke bottle system. The trough for the water outflow was too small but was remedied with a larger diameter pipe. There were issues with the mechanism that keeps oysters from draining out. Through experimentation, we found the balance of correct density and materials which would minimize loss of oyster seed.
In the construction of the coke bottle upweller system some challenges occurred. To start, the three inch half pipe volume was inadequate to support the volume of water flowing out of the 20 bottle units. To solve this a new three inch pipe was cut, removing a quarter of it leaving a larger volume to support the water flowing from the 20 bottle units. After the trough was fixed to collect the discharge from the bottle, larger oysters (R1.5/2mm) were placed in the bottles to run the system. Larger oysters were used, since we had a failed oyster spawn and were unable to use small oysters (less than 1mm). While testing with the larger oysters we determined that the acrylic balls, that are used to keep the water and oysters in the bottle when water flow is shut off, were less dense than the oysters. Therefore, the acrylic balls did not keep the oysters from draining out of the bottles. To solve this problem denser glass marbles were used to keep the oysters in. Although this worked to keep the oysters in, the marble crushed the oysters and therefore had to be modified. Experiments were conducted and it was concluded that covering the marble with a rubber elastic would prevent the marble from crushing the oysters. The modified glass marbles were also successful in keeping the oysters in the bottle when water flow is off. Using the modifications, we will now be able to utilize the system to collect data to determine the most practical density. Once this is accomplished, it will result in an increase in production without compromising the health or growth of the animals. This information would benefit individuals that are interested in finding a more efficient way to grow juvenile oysters.
Based on the changes we made to the design of the system, we have minimized the risk of losing oysters when they become available to be tested in the system.
The staff of the hatchery has improved upon the original design and gained knowledge in how to operate the system. This is crucial to gather data when oyster seed becomes available.