Location: Subtropical Plant Pathology Research
2023 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
Researchers at Florida Atlantic University (FAU) and Fort Pierce, Florida in collaboration with Purdue University studied immune response of juvenile Florida pompano in varying salinity (8, 12, 20, and 28 ppt) for 15 days to the pathogen Vibrio sp. Health measures included individual photographs, morphometrics, gill arches for histology, water samples and skin swabs for verification of Vibrio, and tissue samples for transcriptomic and fatty acid analysis. Results showed no effect of low salinity on pompano juveniles’ overall health, suggesting the safety and economic benefits of rearing pompano at low salinity. Maintaining marine salinities within inland recirculating aquaculture systems (RASs) requires large amounts of salt that increases costs. An on-farm study previously done explored this issue in larvae, but this additional study was conducted to focus on the effects of salinity on immune function and pathogen susceptibility. A manuscript is currently in preparation with anticipated Summer 2023 submission. Researchers and partner fish farms, LAB and Proaquatix, tested commercial live feed replacement diets at differing substitution levels to reduce the need for rotifers and Artemia for larval pompano. This will enhance efficiency and reliability of hatchery and early nursery phases. Live feeds are expensive for marine fish hatchery production. INVE Natura pRo (<100um & 100/250 um) and ExL (200/400 um & 300/600 um) are designed to reduce the need for rotifers and Artemia by at least 50%. We tested three treatments with a control, rearing fish until 3 days post hatch (dph) in quadruplicate on two farms. Experimental treatments replaced 50% and 80% of rotifers and Artemia, and 80% of Artemia. Our results show the potential of INVE as a replacement for live feed, we found that survival, length and weight were comparable in fish from all the treatments to the control. This live feed replacement will allow for an option for hatcheries if one or more of their live feed culture fails during a hatchery run. Elimination of Artemia will reduce exposure to potential pathogens such as Vibrio that is found in Artemia cysts.
FAU and ARS Fort Pierce, Florida in collaboration with the University of Maine-Orono conducted a 10-week feeding trial with juvenile pompano to determine adequate dietary carbohydrate sources for optimal growth. Five diets differing in carbohydrate sources were tested (whole wheat grain flour, whole corn grain flour, wheat starch, corn starch, and dextrinized cornstarch). Results showed that whole wheat grain flour is the best carbohydrate source for pompano showing the highest weight gain and feed efficiency among other optimal health status parameters. These results are of high importance when formulating a well-balanced diet that will provide the energy requirements with carbohydrates that spare the use of protein for growth. Researchers in collaboration with River Road Research-Noco assessed the effects of replacing fish meal (FM) with black soldier fly meal (BSFM) in red drum juveniles. BSFM is a protein source that is gaining attention in aquaculture for its sustainable production and well-balanced amino acid profile. Five diets differing in FM replacement (25, 50, 75 and 100%) were tested to evaluate growth. Results showed that fish fed with a 50% BSFM diet presented no difference from the controls fed 100% FM diet. These results highlight the possibility of replacing up to 50% of the fish meal which will reduce production feeding costs.
In collaboration with Auburn University we studied species-specific feed formulations for pompano, by evaluating the use of specialty soybean meal to replace animal proteins (AP). Comparison of soy-based feed (8% poultry meal, 10% corn protein concentrate, 55% soybean meal) to a commercial feed was done in two different systems with 6 replicates of each diet in small (800 L) and large (3000 L) tanks for 8 weeks. Final weight, percent weight gain, and feed conversion ratio (FCR) for fish reared on the experimental feed were generally poorer than that of fish reared on the commercial feed, respectively. A similar response was observed in the large tank system (3,000 L). In both cases, performance was poorer, but not significantly (P < 0.05), in fish fed the experimental diet compared to the commercial feed. This would indicate that although we were close in performance, optimization of diets with low levels of AP and high levels of plant proteins is still needed.
Collaboration with Florida A&M University we studied growth effects of replacing FM at varying levels of hemp seed meal (HSM) (5, 10 and 15%) with or without taurine supplementation in pompano and red drum. The HSM is a by-product from hemp processing, is 30 – 40% protein and high in polyunsaturated fats, serves as potential feed ingredients. This study showed that HSM had no adverse effect on either species, with the survival ranging from 85 – 100% for pompano and 90 -100% for red drum. The growth of both species was significantly affected by replacing FM with HSM, with respect to the control diet. Increased levels of HSM without taurine supplementation reduced fish weights. However, fish fed with HSM diets supplemented with taurine presented the highest weight gain. Five percent HSM diet supplemented with taurine presented an optimal nutritional balance for both species.
Objectives. 1 and 3. We studied optimizing egg quality in pompano broodstock for consistent and high-quality seed stock production. A mix of 40 wild caught and F1 generation pompano broodstock were divided into 4 tanks in 2 RASs. Three different treatments of cut-bait diet, commercial feed Breed-M, and an Ulva based diet with a 10% fish meal substitution were fed 4 times a day at 10% of fish body weight. Egg and larvae samples were collected for biometrics and biochemistry twice a day prior to complete yolk absorption and once a day until weaning onto a microparticulate diet. Yolk reserves were used differently between offspring of parents fed cut bait diet those fed pelleted diet. Larvae from pellet fed brooders had faster growth and more consistent fatty acid (FA) composition. Similar effects were noted with Almaco Jack broodstock collaborating with Mote Marine Laboratory. We evaluated cut bait and pelleted broodstock diets for egg and larvae quality. Offspring showed better growth and more consistent composition in essential FA. These experiments are still ongoing with other commercial diets to be trialed. Results were presented at Aquaculture America 2023 in New Orleans, with pompano results being part of a masters student thesis.
Studies show that eggs are influenced by broodstock diet but there is no information on the timeline of nutrient incorporation. In collaboration with Hubbs Sea World, have built on findings for California yellowtail broodstock diet’s impact on egg quality to study the duration required for broodstock to transfer dietary nutrients to eggs. Nine California yellowtail females were fed alternating diets of commercial pellet and cut bait. Each diet was switched every 6 weeks within the 24-week spawning season. Egg biochemical and biometric data were analyzed for differences in diet type and spawn period. Parameters (i.e., fertilization rate) stayed consistent but egg FA composition was affected by diet and spawn period. Egg FAs showed that pelleted diet FAs were incorporated in 10 days, but cut-bait FAs took 20 days. Analysis using egg:diet ratio found that only arachidonic acid satisfied requirements for eggs while eicosapentaenoic acid, docosahexaenoic acid and essential FA precursors, linoleic acid and a-linolenic acid, were not met. Known incorporation rates will allow informed feeding planning when testing new feeds or supplements. These results will transition producers from cut-bait to pelleted diets.
Objective 2. Researchers initiated a genome based selective breeding for pompano. A transcriptome for Florida Pompano was completed based on whole-body juveniles and skeletal muscle transcripts. The transcriptome and whole-genome assembly allows for gene prediction and identifying non-coding sequences useful as markers. The final set of predicted protein-coding genes was 26,891. Ortholog analysis of the six related fish species identified 13,088 orthologs, with 259 genes unique to Florida pompano. This information will be used as a tool to identify genes associated with traits of interest to commercial aquaculture (e.g., growth, disease resistance, and fecundity).
The genomes of two closely related species, permit and palometa, were sequenced, assembled, and annotated to compare with growth genes to pompano. This showed eight species-specific growth genes in the pompano and one in palometa. The unique pompano growth genes were TGFBR3, IHH, NDRG4, MTPN, Smad4, SGMS1, and ZRANB3. Permit and pompano each had one species-specific orthogroup containing two genes. This information allows investigating why permit is 10x larger than pompano and will be used in a marker assisted selective breeding program.
Objective 3. We established a Fish Health & Pathology Lab suitable for isolation, cultivation, and identification of common BSL-2 disease microorganisms in marine warm water finfish. We designed and began setting up a disease challenge lab for pathogen/parasite inoculation and observation. This facility will consist of two 40 ft insulated shipping containers with environmental control. One will house 12 individual RAS for challenge studies while the other will house a bench lab. The containers are set and connected to electricity and running water.
Ongoing facility updates: Structural renovation of greenhouses is complete. Rebuilding of grow out systems inside is ongoing. Larviculture lab has been built and temperature control heating and cooling systems are complete. Tanks will be set in place next.
Accomplishments
1. Whole wheat grain is a good source of carbohydrates for farm raised Florida Pompano. Several carbohydrate sources were tested in feeds for Florida Pompano by researchers at Fort Pierce, Florida. Whole wheat grain was the best carbohydrate option of those tested, for Florida pompano feed formulation. It resulted in better growth performance in Florida pompano juveniles, showed excellent growth, feed intake, and feed efficiency than other sources of carbohydrates tested. Carbohydrates are the cheapest dietary energy and adequate dietary inclusion can reduce protein and lipid use for energy. This ultimately reduces feed cost and waste ammonia release to the environment. Therefore, the benefits include lowering feed costs without affecting the nutritional balance of feed and will contribute to the economic sustainability of aquaculture operations.
2. Florida Pompano protein coding gene set (a.k.a., Transcriptome) was completed. The researchers at Fort Pierce, Florida, fully identified a full set of protein coding genes in Florida Pompano and closely related Permit, and Palometa. This established data set will allow for the identification of novel genes associated with traits of interest that can be used in a selective breeding program. This allows researchers to identify the variation in the growth genes between these three species to look for a genetic linkage between the different sizes for these three related species. Benefits to fish farmers include identifying genes associated with growth that can be used in a selective breeding program. This will allow for the selection of fish who reach market size faster and with less size variation resulting in increased yield and profits for farmers.
3. Hosted an industry/stakeholder informational workshop. To ensure U.S. marine finfish aquaculture industry and taxpayer interests are met, it is essential to inform interested parties on programmatic progress and seek input on future programmatic direction. ARS researchers in Fort Pierce, Florida, in coordination with the U.S. Warm Water Marine Finfish Aquaculture Advisory Committee, hosted a workshop to disseminate programmatic progress and seek input for future programmatic direction. The workshop successfully encouraged the ongoing dialogue between project researchers, industry, and other stakeholders. The documented outcomes were productive and instrumental in underscoring ongoing stakeholders’ needs and refining new industry challenges. The benefits to industry and the U.S. consumer are a very directed and focused effort to increase production efficiencies and a better tasting product brought to market safer, faster, and more economically.
