Location: Subtropical Plant Pathology Research
2022 Annual Report
Objectives
The U.S. has tremendous capacity for meeting the domestic demand for seafood by expanding aquaculture in federal waters and land-based recirculating systems. As the largest importer of seafood products, expanding domestic production will reduce our reliance on imports and the trade deficit. This project will support the U.S. aquaculture industry by developing technologies that will ensure a steady supply of warm water marine fish seedstocks that are optimized for commercial production.
1. Develop year-round spawning strategies for captive broodstock and larviculture methods for seed production of marine finfish.
2. Develop methods for genetic improvement of warm water marine finfish for optimum production efficiency.
3. Increase understanding of fish physiology and enhance production efficiency through improved management strategies.
Approach
Aquaculture producers need access to seedstocks that are available year-round and optimized for the production environment. Research is needed to develop seedstocks that are bred for maximum production efficiency and have minimal impacts on the environment and native populations. Research in the disciplines of genetics, fish health, nutrition, reproductive biology, and physiology will contribute to the development of seedstocks that meet these criteria.
Progress Report
This is a report on the first three years (FY2020-2022) progress of a multi-year USDA-ARS collaborative research partnership with Florida Atlantic University’s Harbor Branch Oceanographic Institute (HBOI). The project began during the 2nd year of a standard USDA project planning cycle. There is no existing standard 5-year plan. A 5-year plan is scheduled after the first 4 years of the project. During these initial 4 project years annually prioritized experiments are being determined in consultation with industry stakeholders and USDA-ARS.
In support of Objective 1, researchers at HBOI-FAU partnered with local fish farms in Florida, to address the knowledge gaps regarding the impact of low salinity on Florida pompano larval health and well-being. An experiment was completed with larval Florida pompano reared in 3 different salinities (10, 20, and 30 ppt), to determine the optimal salinity for culturing fingerlings from hatch to weaning under commercial production settings. Results indicated Florida pompano reared in a salinity as low as 10 ppt remained healthy with normal growth and physiological development. Raising Florida pompano under low salinity has several benefits, including the reduced reliance upon coastal properties for the siting of production facilities that could alternatively be constructed inland close to market centers reducing the carbon footprint and providing local jobs. In addition, this would reduce the expenses associated with buying artificial seawater. These efforts resulted in two peer-reviewed manuscripts, one on physiology (biometrics, biochemistry, and general transcriptomics), and the other on immunology (gill structure, microbial communities, and immune genes).
HBOI researchers partnered with local Florida fish farms to establish the effect of early weaning (transitioning to prepared diets) on improving production, survival, and growth of Florida pompano under current commercial hatchery production protocols. In 2020-2021, researchers at HBOI evaluated three commercially available domestic diets (Bio-Oregon, Zeigler starter, and Otohime) on Florida pompano larval growth and survival. Only the Otohime fed fish resulted in satisfactory production performance. A subsequent investigation was conducted to demonstrate early weaning under commercial conditions using Otohime and two additional commercial diets (Love larvae, and INVE Natura) which exhibit better performance in marine fish larvae reared overseas. Performance was investigated from hatchery all the way through to grow-out to market. In addition to growth and survival, weaning diet effects on the fish gut microbiome was also determined. Reducing the time from hatch to feeding a prepared diet (weaning) results in a significant cost savings for a hatchery producer. Samples of fish for weights, length, biochemistry, bone and cartilage form and structure, as well as the microbial community are currently being analyzed.
Researchers at HBOI in collaboration with Sea Watch International, Ltd. conducted a 12-week feeding trial on juvenile Florida pompano to assess the suitability of clam meal as a substitute for fish meal in Florida pompano diets. Clam meal was added at 10, 20, or 30% of the diet. The effect of clam meal on growth, efficiency parameters, body composition, health parameters, and gut microbiome were investigated. Juvenile Florida pompano fed 10 and 20% clam meal had a higher weight gain, protein retention, as well as a better oxidative stress response than the pompano fed the fish meal diet. Additionally, there was no impact on the microbial diversity of the gut. The results demonstrate that clam meal has comparable performance and health benefits as observed in the pompano fed the fish meal diet, indicating clam meal is a suitable replacement for fish meal. These efforts resulted in a peer-reviewed manuscript. In addition, a report is in preparation for submission to the Food and Drug Administration (FDA) and the Association of American Feed Control Officials (AAFCO) for approval as a new animal feed ingredient for marine fish diets.
In support of Objectives 1 and 3, researchers at HBOI, in collaboration with Mote Marine laboratory have been establishing the dietary impacts on egg and larval quality and survival to determine an ideal maturation diet for Florida pompano broodstock. Broodstock at HBOI were conditioned on a traditional cut bait diet and were spawned in December 2021, and again in February 2022 to obtain baseline data on the spawn quality of the broodstock. The broodstock is currently in conditioning cycle and will be fed two more maturation diets; Breed-M and an Ulva-based pelleted diet, after which spawning will occur to determine the effects of these diets on egg and larval quality.
In collaboration with Hubbs Sea World Research Institute in California, and Mote Marine Laboratory, California yellowtail and Almaco Jack broodstock diets were evaluated to determine the best diet for developing high quality eggs and larvae. Fecundity, hatch success, and survival were positively correlated to dietary treatments for both species. In California yellowtail, two commercial diets (Breed-M and Bio-Oregon), met the essential fatty acids requirements when compared to the traditional cut bait diet. A feeding experiment with Almaco Jack, evaluated different types of cut bait diets. Most of the cut bait diets had sufficient amounts of the essential fatty acid DHA, but were deficient in the essential fatty acids EPA and ARA. The results of these experiments suggest that commercial diets are a better option for a consistent good quality eggs and larvae. This accomplishment allows farmers to reduce feed cost and increase biosecurity by reducing the use of cut-bait for broodstock feed. A manuscript regarding these efforts is in preparation for submission to the peer-reviewed North American Journal of Aquaculture. Researchers at HBOI in collaboration with Hubbs Sea World Research Institute completed a successful out of season conditioning program for California yellowtail. This accomplishment allows for out of season spawning to support egg and larval supplies year-round.
In support of Objective 2, researchers at HBOI are establishing a selective breeding program for Florida pompano. To support this program, it is essential to document the genetic variation within the wild population. Fin clip samples from 32 West Coast Florida pompano were collected to determine the genetic variation between the Florida East Coast and West Coast strains. The sequencing results established that a significant number of gene flow occurs between both East and West coast strains, suggesting that they form a single population. Results were presented at the World Aquaculture Society 2022 Conference, March 2022 in San Diego, California. Further analyses are being conducted to identify any genetic variation that may occur within protein coding genes. In addition, this same approach was applied to red drum. Fin clips samples from 42 red drum were collected from Florida East and West Coast locations.
In support of Objectives 2 and 3, researchers at HBOI documented the use of copper treatments in marine food fish reared in recirculating aquaculture systems. Chelated copper and copper sulfate are used to prevent parasitic infections and excessive algal growth. However, copper treatments result in an increase in metal resistant bacteria, associated with antibiotic resistant bacteria. The differences were established between the microbial communities and genes associated with resistance (antibiotic, metal, and biocides) between bacterial films taken before copper treatment and up to 50 days after chelated copper treatment was halted. It was documented there was an increase in the diversity and abundance of antibiotic and metal resistance genes. This suggests that bacterial film in the tank could be a reservoir for resistance genes and a risk to fish health.
Researchers at HBOI in collaboration with the Autonomous University of Barcelona, Spain initiated a histology Atlas for Florida pompano to develop a comprehensive baseline of normal organ and tissue development from hatching to 95 days post hatch. A clear-staining technique that allows visualization of the cartilage and skeletal system development has been developed. Histological examination of the tissues is ongoing for inclusion in the Atlas. In addition, to inform marine finfish culturists of potential pathogens and to identify current gaps in the development of diagnostic tools and available treatments, a 130-page book was prepared. The document features aspects of the pathology, prevention, and treatment for 45 diseases or health-related conditions of three marine farmed finfish belonging to the families Carangidae (pompanos, Trachinotus spp.; yellowtails, Seriola spp.) and Sciaenidae (red drum, Sciaenops ocellatus). It describes more than 60 causative agents (viruses, bacteria, and parasites), as well as geographical distribution and specific hosts affected.
Researchers in collaboration with local fish farmers are developing a noninvasive environmental DNA (eDNA) method for monitoring fish health. eDNA is used to screen for common disease-causing microorganisms including the dinoflagellate parasite Amyloodinium ocellatum and for pathogenic Vibrio species such as V. anguillarum. In-field methods for rapid pathogen/parasite detection and microbiological surveillance are being developed for use in an aquaculture farm setting to help farmers reduce disease related mortalities. The results will lead to the development of a noninvasive eDNA tool that will be available to marine aquaculture farmers nationwide.
Accomplishments
1. Clam meal economical feed component for farm-raised Florida pompano. Clam processing by-product represents expensive and environmentally challenging disposal problems for the clam processing industry. Researchers in Fort Pierce, Florida, in collaboration with Sea Watch International established that clam meal can be used as a suitable substitute for other more expensive and less sustainable fish meal ingredients in fish feed fed to farm-raised Florida pompano. This clam meal promotes growth, health, and well-being in farm raised Florida pompano as well as high quality fish meal. This processing waste-stream could be used at rates as high as 20% of the complete diet. This accomplishment represents a more sustainable fish feed, a potential feed cost reduction, in addition to potential new revenue stream for an additional industrial manufacturing process.
2. Advances in Yellowtail jack spawning and diet promote this U.S. industry. The Yellowtail jack is a U.S. consumer favorite, and there are ongoing efforts to establish offshore net-pen farms for their production in U.S. waters. However, year-round production of juveniles to stock these farms, as well as safe and efficient diets for feeding spawning fish to produce efficient, hardy, and robust juveniles remain challenges to the industry. Researchers in Fort Pierce, Florida, in collaboration with researchers from Hubbs Sea World Research Institute in California have established methods for the successful out of season spawning of Yellowtail broodstock. In addition, it was demonstrated that commercially available diets can be used to produce high egg and larval quality and quantities to make the U.S. industry competitive. This accomplishment benefits consumers and Yellowtail producers alike by providing a more steady, consistent supply of high-quality product year-round.
3. Increased knowledge of microbiome changes following copper sulfate treatment improve aquaculture production safety. Copper sulfate is used by farmers for the treatment of parasitic infections and excessive algal growth. However, previous indications in other settings suggest that the film of microbes in aquaculture systems can exhibit an increase in the number of microbial metal and antibiotic resistant genes following treatment with copper sulfate. Researchers in Fort Pierce, Florida, evaluated the effects of copper sulfate on microbes within a tank following completion of the treatment regimen and documented an increase in the types and numbers of metal and antibiotic resistant genes over time. This accomplishment provides U.S. fish farmers with improved guidelines for copper sulfate use that will result in a safer and healthier stock, while reducing risk to the environment of developing metal and antibiotic resistant genes.
4. Quantification of Florida Pompano population genetics promotes improved broodstocks. Selective breeding programs with terrestrial livestock and a limited number of farm-raised fish species indicate it is possible to identify genes encoding beneficial production traits that can be selected for in the parental stock and result in faster and more efficient growth, greater disease resistance or higher quality products. In selecting the parental broodstock, it is essential to understand the genetic makeup of the parents to maximize the diversity in the gene pool, but not contaminate the existing gene pool. Researchers at HBOI have established that the wild populations of Florida Pompano off the Atlantic/East Coast of FL and the Gulf/West Coast of Florida are genetically similar suggesting they are one population. This accomplishment provides a greater understanding of the genetic variation found in the wild and is important when collecting individuals for a broodstock that will result in juvenile fish with faster growth and a higher quality product to supply to U.S. consumers.
