1a. Objectives (from AD-416)
The objectives of this cooperative research project are to: 1) develop feeding management strategies and diets for optimal growth, efficiency, and reproductive success of high-value marine finfish reared in low salinity recirculating systems; 2) develop year-round spawning strategies for captive broodstock and larviculture methods for sustainable seed production of high-value marine finfish species; and 3) develop engineering processes and sustainable effluent technologies to enhance water and energy utilization and reduce environmental impacts within, and discharged from, low-salinity recirculating aquaculture systems.
1b. Approach (from AD-416)
ARS will conduct cooperative research with Florida Atlantic University at Harbor Branch Oceanographic Institute (HBOI). In consultation with the ADODR, cooperative research will be conducted in efforts to design and evaluate cost-effective recirculating nursery and growout production systems for marine finfish cultured in low-salinity water. Cooperative research will primarily focus on four companion areas of study. Area one will focus on determining nutrient requirements and development of feeding strategies and diets for optimal growth, efficiency, and reproductive success of marine fish reared in low-salinity recirculating systems. Area two will focus on developing year-round spawning strategies for captive broodstock and development of early juvenile rearing methods for sustainable seed production of selected marine finfish species. Area three will focus on developing engineering processes and sustainable effluent technologies that enhance water and energy utilization and reduce environmental impacts in low-salinity environments. Area four will focus on disease management strategies for recirculating aquaculture production systems.
3. Progress Report
During the reporting period the parent project was identified for closure as a Congressional earmark reduction. The progress reported here builds on the accomplishments of FY2010 and represents progress between the beginning of FY2011 and termination of the parent project; this project has been associated with a new parent and will continue into FY2012. Accumulation of compounds that impart unpalatable flavors to harvested fish presents a challenge to the aquaculture industry, particularly when recirculating aquaculture technologies are used. Therefore, after a long-term growth trial a novel approach was compared to the traditional approach for removing two common compounds (Geosmin and methylisoborneol) that tend to accumulate in the water and fish flesh of fish reared in recirculating aquaculture systems. Fish were reared in four traditional recirculating systems and four simplified energy-efficient alternative recirculating aquaculture systems for 263 days. Following the growth period, a filtration device containing 22 kg of wax paraffin beads was installed on two systems within each of the two system types to remove the compounds. The filtration device was evaluated relative to traditionally used large-volume water exchanges. Water samples and fish fillets were collected over a 14-day depuration period and samples analyzed for Geosmin and methylisoborneol residues. In addition, at the initiation and again at the termination of the depuration period, samples were collected for taste panel evaluation conducted by the University of Florida, Gainesville. No differences were detected between the filtration and traditional depuration methods in either type of recirculating system based on Geosmin or methylisoborneol concentration in either the water or fillet samples. Taste panel analysis showed a preponderance of off-flavor in all of the fish prior to initiation of the depuration process, characterized as very strong, strong, or moderate and which was likely related to Geosmin, based on the panel's characterization. None of the fish samples were characterized as off-flavor at day 14. Although the filtration device did not improve depuration efficacy over traditional methods, this method proves to be an encouraging alternative in areas where water or water discharge is a limiting constraint to aquaculture production. The ADODR is in regular contact with the cooperator via phone, email, and regular site visits.