Location: Cool and Cold Water Aquaculture Research2021 Annual Report
Objective 1. Improve fish health, performance, and welfare in recirculating aquaculture systems. Sub-objective 1.1 Evaluate salmonids grown to market size in a semi-commercial scale freshwater RAS. a): Collaborate with NCWMAC to evaluate multiple strains of Atlantic salmon and their performance in a RAS environment. b): Assess genetic strain of steelhead (including USDA-strain rainbow trout) raised to 4kg in a RAS environment. Sub-objective 1.2 Assess environmental manipulation to reduce maturation in mixed-sex diploid Atlantic salmon. Sub-objective 1.3 Improve biological monitoring and management of salmonids in RAS through technological integration of next-generation biomonitors. Objective 2. Support land-based salmonid recirculating aquaculture systems production through increased technological and operational efficiencies and novel, supplemental revenue streams. Sub-objective 2.1 Evaluate methodologies to convert RAS waste to value-added products. 1a: Assess feasibility of new composting technologies of RAS waste solids and their capacity to generate sellable products. 1b: Assess feasibility of anaerobic digestion of RAS waste solids to generate biogas/energy. Sub-objective 2.2 Assess novel methods to improve RAS water quality, including optimized integration of membrane biological reactors. Sub-objective 2.3 Pilot and evaluate new computing technologies for RAS integration to optimize system operational efficiencies.
The domestic salmonid aquaculture industry is currently experiencing a significant departure from traditional farming practices, as evidenced by recent, substantial capital investment in large-scale land-based, closed-containment facilities utilizing water recirculation aquaculture system (RAS) technologies. While this is an encouraging evolution for U.S. aquaculture overall, this relatively new approach to raising market-sized Atlantic salmon, steelhead trout, and other economically important species is still a frontier in agriculture, remains largely untested at commercial scale, and requires significant refinement and optimization in technological, biological, and economic methods and strategies. The Conservation Fund Freshwater Institute (TCFFI), an extramural program of the USDA-ARS, has been at the forefront of RAS technology research and development for over two decades, and at present we are uniquely suited to continue serving this growing agricultural sector through focused, industry-relevant research and innovation. Our next 5-year project plan seeks to address critical areas that are necessary to support the sustainable growth of the U.S. land-based, closed-containment aquaculture industry; specifically, our objectives fall under two broad categories aimed at improving i) the biological performance of salmonids in RAS, and ii) the technical and economic efficiencies of land-based closed-containment operations. Research activities will include identifying genetic strains of Atlantic salmon and steelhead for optimal performance in RAS, assessing methods to reduce early sexual maturation and improve water quality, developing next-generation biomonitors and computing technologies to improve fish health management and RAS environmental control, and developing means for RAS producers to monetize waste streams for enhanced economic viability.
Progress towards Subobjective 1.1 has included performing a grow-out trial (target final size: 4 kg) in semi-commercial scale recirculation aquaculture system (RAS) focusing on steelhead trout, representing six separate varieties: i) USDA High Fillet Yield line of rainbow trout; ii) Troutlodge all-female diploid; iii) Troutlodge all-female triploid; iv) Riverence all-female diploid; v) Riverence all-female triploid (pressure shocked), and vi) Riverence all-female triploid (heat shocked). Additional Troutlodge all-female diploid steelhead was also stocked as “filler fish” for the growout trial, i.e., additional biomass to maintain commercial densities. The steelhead has been successfully raised to 3.5 kg at the time of report submission, with regular performance and welfare assessments having been carried out since stocking, including data collection on length, weight, fin condition, deformities, condition factor, coefficient of variation, and survival. Final performance assessment and product quality data collection will commence when a 4 kg mean weight is achieved. In support of Subobjective 1.2, having installed and maintained chillers in the experimental-scale RAS in order to create the experimental conditions necessary for this study, we raised post-smolt Atlantic salmon to target size in either 12 degreeC or 14 degreeC replicated RAS. At study termination, maturation was assessed via gonadosomatic index (GSI) quantification (with thresholds of either 0.2% or 1.0% GSI to indicate maturation commencement) and via external morphological signs. Significantly (p<0.05), higher maturation was observed in salmon reared at 14 degreeC when using the 0.2% GSI threshold; however, maturation was still relatively high (21.2%, vs. 34.3%) in the 12 degreeC treatment group, indicating that optimal rearing temperature for post-smolts in RAS is likely less than 12 degreeC. The results of this study are currently being written for peer-reviewed publication and will be presented at Aquaculture America 2021. In support of Subobjective 1.3, all-female diploid eyed Atlantic salmon eggs have been imported from Stofnfiskur (Iceland) and will be smoltified once mean weight has reached 40 g (current size: 0.4 g), after which experimental conditions of high vs. low nitrate in six replicated experimental-scale RAS will be established, and stress response will be evaluated through analysis of data derived from implanted biomonitors. Progress towards Subobjective 2.1 has included the completion of two bench-scale anaerobic digestion (A.D.) studies, with a third experiment currently ongoing. Using standard biochemical methane potential tests to evaluate biogas produced from RAS salmonid sludge, early data suggest a high economic potential for converting solid wastes into useable energy. This early work provides critical baseline information regarding the waste-to-value application of A.D. to RAS salmonid sludge and will inform subsequent on-site pilot-scale A.D. experiments. Due to COVID-19-related materials supply issues, construction of a pilot-scale A.D. system has been delayed (to be completed in 2022), and in response to this setback, efforts have been shifted to the subsequent research milestone focusing on composting. An optimal compost recipe and rotation schedule in an Ecodrum ™ composting system will be developed in 2021 for RAS waste solids, mortalities, and offal. Beyond this, future planned studies will evaluate potential solutions to gaseous nitrogen losses and will develop a compost recipe for the digestate leftover from the A.D. process. As discussed in our previous Annual Report, Subobjective 2.2 was conceived as follow-up research to a previous on-site USDA-ARS Membrane Biological Reactors (MBR) study and was initially planned to be carried out during the first half of 2020. However, assessment of the experimental-scale MBRs revealed that significant maintenance and potential retrofitting were required to begin this study, and we requested a postponement in study commencement in order to carry out the necessary maintenance. We anticipate that the MBRs will be brought back to operational status in late 2021 or 2022. In support of Sub-objective 2.3, a number of aquaculture-specific technology platforms and potential commercial partners were reviewed for advancing our precision aquaculture research, and we are currently pursuing a more generic commercial machine learning service approach, Roboflow, to apply to our RAS-specific research objectives while also building expertise in Python, OpenCV, and complementary programming tools for use on USDA’s SCINet platform. We have tested a variety of commercially available camera platforms for our underwater machine vision applications in both the steelhead RAS growout trial and in other underwater scenarios and expect to present these findings in a forthcoming scientific paper. We also have monthly informal discussions with the aquaculture startup Reeldata to find areas of common benefit.
1. Reducing early maturation in Atlantic salmon through temperature manipulation. The development of land-based recirculating aquaculture system (RAS) fish farms for producing market-size Atlantic salmon is becoming a significant growth area in U.S. aquaculture. However, the RAS environment is prone to having unacceptable levels of early maturing salmon that are considered a downgraded product and lost revenue. Extramural ARS scientists in Shepherdstown, West Virginia, investigated the impact of water temperature on early maturation in Atlantic salmon post-smolts in RAS. Findings indicated that salmon raised at a lower temperature demonstrated a 38% reduction in early maturation prevalence. These findings will assist farmers in lowering early maturation and thereby increasing the economic viability of their operations.
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Choudhury, A., Lansing, S. 2020. Biochar addition with Fe impregnation to reduce H2S production from anaerobic digestion. Bioresource Technology. 306:123121. https://doi.org/10.1016/j.biortech.2020.123121.
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Choudhury, A., Felton, G., Moyle, J., Lansing, S. 2020. Fluidized bed combustion of poultry litter at farm-scale: Environmental impacts using a life cycle approach. Journal of Cleaner Production. 276:124231. https://doi.org/10.1016/j.jclepro.2020.124231.
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Lazado, C.C., Good, C.M. 2020. Disinfection strategies of Norwegian and North American land-based RAS facilities: A comparative insight. Aquaculture. 532:736038. https://doi.org/10.1016/j.aquaculture.2020.736038.
Gorle, J.M., Terjesen, B.F., Summerfelt, S.T. 2020. Influence of inlet and outlet placement on the hydrodynamics of culture tanks for Atlantic salmon. International Journal of Molecular Sciences. 188:105944. https://doi.org/10.1016/j.ijmecsci.2020.105944.
Choudhury, A., Lansing, S. 2020. Adsorption of hydrogen sulfide in biogas using a novel iron-impregnated biochar scrubbing system. Journal of Environmental Chemical Engineering. 9:104837. https://doi.org/10.1016/j.jece.2020.104837.
Stiller, K.T., Kolarevic, J., Lazado, C.C., Gerwins, J., Good, C., Summerfelt, S.T., Mota, V.C., Espmark, A.O. 2020. The effects of ozone on Atlantic salmon post-smolt in brackish water-establishing welfare indicators and thresholds. International Journal of Molecular Sciences. 21(14):5109. https://doi.org/10.3390/ijms21145109.