Aquaculture America 2023

February 23 - 26, 2023

New Orleans, Louisiana USA


Yuanzi Huo*, Kevin Stuart, Federico Rotman, Mark Drawbridge


Hubbs-SeaWorld Research Institute, 2595 Ingraham Street, San Diego, CA


A modular pilot-scale system for intensive land-based poly-culture of fish, sea cucumbers, mussels and macroalgae was established using a recirculating integrated design aimed at optimizing resource utilization, whilst reducing water requirements and nutrient discharge levels. The first module (Module-1) was included California yellowtail (Seriola dorsalis) as the primary “fed” species in one 1,057 L tank and Ulva lactuca in three cone-bottom 770 L tanks as the biofilter. Effluent containing solid and dissolved nutrient wastes from the fish tank was passed through a drum filter for solids removal. Seawater from the drum filter entered into a sump by gravity, and a side loop of seawater was pumped from the sump through a chiller and back into the sump for temperature control. Sand-filtered, UV sterilized makeup seawater was added to the sump at 1 L/min. Seawater was pumped from the sump through a UV sterilizer prior to going into the U. lactuca tumble culture tanks and then back to the fish tank through central standpipes. The second module (Module-2) housed Mediterranean mussels (Mytilus galloprovincialis) and warty sea cucumbers (Aparastichopus parvimensis) in separate serial rearing units that were replicated. Backwashes occurred automatically and effluent from the drum filter was directed to a cone-bottom mixing tank.  Overflow from this mixing tank flowed into separate parallel 78 L cone-bottom tanks that contained M. galloprovincialis as suspension feeders. Aeration was used to keep particles suspended in the mussel tanks.  Effluent from mussel tanks was directed to a second mixing tank, and then flowed by gravity into three parallel 339 L rearing troughs that held A. parvimensis. Fish feed was the only external nutrient source introduced into this system. Two trials of two weeks each were conducted – one at an initial fish stocking density of 5.2 kg/m3 (Trial 1), and another at 20.9 kg/m3 (Trial 2). The stocking densities of other species, seawater flow rates and aeration levels were determined based on earlier pilot studies. Yellowtail grew on average 0.36 %/d and 0.64 %/d with the food conversion ratio of 1.88 and 1.60, respectively, in Trial 1 and Trial 2. Ulva lactuca showed reliable growth of 24.39±2.00 and 15.57±2.47 g DW/m2/d with a protein content of 15.13±3.11 and 30.36±1.41% DW in each trial, respectively, which resulted in nitrogen removal efficiencies of 0.58±0.08 and 0.75±0.12 g/m2/d.  The performance and solid waste removal efficiencies by mussels and sea cucumbers were monitored in the Trial 2. The condition index (CI) of M. galloprovincialis was not different between the beginning and end of two-week trial, and the solid waste removal efficiencies ranged from 16.1 to 18.9 % of total produced solid waste by the fish culture tank. The condition index of adult A. parvimensis showed no difference between the beginning and the end of the trial, which indicated that the nutritional quality of solid wastes could meet the daily metabolic requirements of adult A. parvimensis. The solid removal efficiencies by A. parvimensis ranged from 16.4 to 20.4 %.  Due to the accumulation of total ammonia nitrogen (TAN) and the surplus of solid wastes inside the system at the high fish density, more tanks of U. lactuca and biomass of solids feeders should be introduced into this system to increase the system productivity and enhance resource utilization efficiencies.