Project Overview
Annual Reports
Commodities
- Animals: shellfish
Practices
- Animal Production: aquaculture
Proposal summary:
Although cryopreservation is a fundamental technology in animal husbandry, the aquaculture industry lags behind other animal production sectors in its use. Oyster aquaculture has barely adopted it at all. Aside from the general lack of adoption of a proven technology, repositories for oyster germplasm do not exist on a worldwide basis, making the oyster industry highly vulnerable to economic losses. Changing environmental and economic circumstances now make cryopreservation not only more relevant, but absolutely critical to the future of the West Coast oyster industry. The proposed work will provide the means for remote shellfish hatcheries to become more efficient, preserve critical germplasm and allow for selective breeding through developing farm-based methods for cryopreservation of oyster gametes. Goosepoint Oyster (GO), Hawaiian Shellfish (HS) and the Pacific Aquaculture and Coastal Resources Center (PACRC) of the University of Hawaii Hilo will work with Dr. Terrence Tiersch of Louisiana State University Agricultural Center (LSUAC) to transfer existing technology and develop and standardize new methods that can be used at the hatcheries in Hawaii and the three partner oyster farms in Washington. The need for improving the capacity of industry stakeholders (farmers, hatchery operators and researchers) to use cryopreservation is urgent due recent events which threaten the oyster industry’s viability. The West Coast industry has moved from wild oyster spat collection for stocking farms to a nearly complete reliance on hatchery production. West Coast hatcheries, are in turn reliant on the Oregon State University Molluscan Broodstock Program (MBP) for genetically selected broodstock for Pacific Oysters (Crassostrea gigas). For nearly 20 years, the MBP has produced selected oyster lines using stocks from the Northwest. It has also introduced a limited amount of new genetic material from Asia. None of this material has been preserved and as funding is dwindling for the MBP since the loss of congressional “earmarks” in 2010, there is great concern that germplasm developed by the MBP and selective breeding programs of individual hatcheries will be lost. The MBP now produces many fewer novel lines each year and industry partners are largely responsible for maintaining lines they find useful. Few hatcheries have the ability to maintain multiple lines. Climate change impacts on the oyster industry also make preserving diverse genetic material important. When material is lost, that diversity is gone forever. The prevailing concept for livestock is to preserve basal material because we cannot predict which genes or alleles will become essential in the future. A good example for this is the need to be prepared to identify disease-resistance genes from repository samples. This is especially relevant to oysters given the impending threat of Oyster Herpes Virus (OsHV-1) which can cause close to complete mortality in Pacific oysters. This disease has devastated several national oyster industries (e.g. Australia). If OsHV-1 reaches the West Coast or Hawaii, consequences will include significant mortality, loss of selected lines, prohibition to transport broodstock and most likely, complete isolation of Hawaii which currently depends on importation of West Coast stocks. Four of the five largest oyster hatcheries which supply stock to Western farms depend on facilities located in Hawaii. The PACRC also has a small seed production facility as part of its Student Aquaculture Workforce Training Program and helps supply seed to 18 farms in the Western region. Although other livestock industries routinely use cryopreservation methods, developing and standardizing methods for use at oyster hatcheries and farms will require substantial research and development. The work described in this proposal encompasses the first, critical steps required to begin this process. This includes: 1) developing collection, handling, and shipping methods from Hawaii and Washington to LSUAC that are reliable and replicable; 2) evaluation of equipment and training needs to establish on-site capacity for the work at remote farm and hatchery sites; 3) development of a plan to utilize cryopreservation for oyster breeding plans, and 4) outreach to a wide variety of users. Adding to the urgency of developing appropriate methods is the scarcity of tetraploid oysters. Goosepoint Oyster was awarded a WSARE grant in 2015 to develop methods to produce tetraploid oysters. Tetraploid male oysters are crossed with diploid females to produce triploid oysters which are preferred for modern oyster farming. Triploids outperform diploid oysters because they stay “fat” throughout the year and are the mainstay for summer harvests when diploid oysters cannot be utilized. The patent for tetraploid oysters expired in early 2015, exacerbating the existing scarcity. Since that time GO, HS, and the PACRC have worked with Dr. Ximing Guo (Rutgers University) to begin producing new tetraploid stocks. The new tetraploids will be used to produce triploids for the 18 farms that GO and the PACRC supply with seed, and for a joint selective breeding program. Production of new tetraploid lines is a costly but necessary exercise. Initially each tetraploid oyster may cost upwards of a $1000 to produce and culture until it reaches sexual maturity. Costs can be lowered and efficiency increased if sperm can be used in aliquots over time rather than using each male’s sperm only once. This is also critical for breeding plans and research. After methods for cryopreserving diploid oyster sperm are developed and can be reliably used by hatchery personnel, these methods can be adapted to tetraploids being developed by the partnership. Additionally, work can then begin with eggs, further increasing the amount of germ plasm available and flexibility in breeding. The PACRC and HS produce other species which will be included in future work.
Project objectives from proposal:
The overall objective is to transfer existing cryopreservation technology and develop new methods as a means to improve farm efficiency and lower costs. We envision this work as a proof of concept that cryopreservation can be adopted at remote farm and hatchery sites.
The initial work will include transfer of existing methods from LSUAC to farms and researchers in Washington and Hawaii and development of new methods sized for these particular entities. Initially only sperm from diploid oysters will be utilized, with the goal of using the frozen material to create founding populations of oysters. Such broodstock development is usually limited to a few hundred or thousands of specimens, as compared to production of millions of harvestable oysters for multiple West Coast farms.
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Future work will include developing methods for cryopreservation of oyster eggs and sperm from tetraploids. Although oyster eggs and sperm from tetraploid males have been successfully frozen, thawed, and used for fertilization in research settings, both are more delicate and present a wider range of problems. Additionally, capacity would need to be scaled up for use in hatchery production of billions of oyster seed for regional distribution. Thus methods and protocols are best developed initially using diploid semen to create founding populations of broodstock.
Specific objectives:
1. Develop reliable and replicable sperm collection, handling, and shipping methods at the three oyster farms in Washington, and the two Hawaii hatcheries. Dr. Tiersch will receive the material at the LSUAC Aquatic Germplasm and Genetic Resources Center, freeze the sperm, then send this back to the Hawaii hatcheries for thawing and use in fertilization tests. Dr. Tiersch has experience with several species of oysters and will focus efforts on developing protocols that can be utilized at the hatcheries involved, removing future need to ship materials to a central cryopreservation facility. This approach could include development of specific devices to enable freezing at the necessary scale at the hatcheries in relation to their existing capabilities.
2. Test cryopreserved sperm at the hatcheries in fertilization trials to assess post-thaw viability and enable estimation of the quantities of material that will be needed for production-scale use.
3. Evaluate the materials, equipment, and training needs for the hatcheries to be able to collect, freeze, and store sperm on-site in remote locations. This will take into account problems such as electrical failures, natural disasters and personnel turn over that affect remotely located farm facilities. A plan for future on-site capacity and a budget will be developed.
4. Contribute specimens of wild and selected oyster lines to the USDA National Animal Germplasm Program (http://www.ars.usda.gov/Research/docs.htm?docid=22314) as back-up reserves of germplasm.
5. Conduct outreach and training for hatchery and farm personnel, students and the wider aquaculture stakeholders.