Summary
Highlights
The video introduces Daniel Robinson, a research officer at the IMA's aquaculture unit, who will be guiding the tour. He is a past student of the Department of Life Sciences and the St. Augustine Campus of the University of the West Indies, making him well-versed in the system's operations.
The tour begins at the IMA's freshwater wet lab, which houses the tilapia production unit. The current species being cultured are red hybrid tilapia and silver tilapia. These are considered rootstock, and the tanks are used for their reproduction. This section also briefly touches on the characteristics of these fish where they tend to be quite hardy and can get to harvestable size in a few months.
Daniel explains the fingerling production process, which primarily takes place in outdoor hapas (nets). To address the problem of varying fingerling sizes, the IMA uses a process called 'grading' or 'detailing' to sort fish into uniform size classes. A fingerling grader, a stainless steel piece of equipment with an adjustable slider, is used for this purpose, which helps to streamline distribution to farmers. The pricing and distribution model for fingerlings to farmers in a specific program at 95 cents a fingerling is also mentioned.
The tour moves outside to the IMA's tilapia ponds. Daniel describes their construction, noting their elevated location, dimensions (5m wide x 10m long, 4-5.5ft deep), and sloped banks for optimal water flow. The ponds are designed to be against the wind for better aeration. He explains the importance of a slight grade in the pond bottom for efficient fish harvesting and complete drainage for cleaning and preparing for new stock. The process of applying agricultural lime to the pond bottom to maintain alkalinity and buffering capacity for optimal tilapia growth is also highlighted. Fertilizers like triple super phosphate are added to maintain an algal bloom, which serves as a crucial food source for the fish, indicating a semi-intensive farming approach.
The video then showcases the marine recirculating aquaculture system (RAS), which is used for larger-scale production research, specifically for Pacific whiteleg shrimp. Daniel explains the water flow pathway, starting from the production tanks where shrimp grow. The tanks have two drains – a bottom center drain for heavier solids (waste, uneaten food) and a side drain for lighter, floating particles.
The first stage of filtration involves a rotating drum filter, a crucial component in modern RAS. This filter, using a stainless steel mesh, removes particles larger than 63 microns. Daniel details its automated self-cleaning mechanism: as the filter clogs, a water level sensor triggers a motor to rotate the drum, while spray bars clean off accumulated debris, which then flows into a wastewater line. This system is efficient, automated, and requires minimal daily maintenance.
After the drum filter, the water moves to a protein skimmer (or foam fractionator). This device uses a pump to create a vortex of air and water, generating fine bubbles and foam. This foam, rich in excess nutrients and proteins, rises and overflows into a collection cup, then is backwashed into the wastewater line. This process is particularly important for marine systems, similar to the foam seen on ocean waves.
The biofilter is introduced as an essential part of any recirculating system, primarily for removing nitrogen. Ammonia, a toxic byproduct from fish waste and uneaten feed breakdown, is converted to nitrites by 'nitrosomonas' bacteria, and then to less harmful nitrates by 'nitrobacter' bacteria. The biofilter tank contains media to increase surface area for bacterial growth, along with aeration to prevent sludge buildup. The system is inoculated with dry powdered forms of these bacteria, and water quality testing confirms successful nitrification. While nitrates are less toxic, their accumulation necessitates weekly or bi-weekly water changes to manually remove them.
The tour proceeds to the control room, which houses the main pump driving the water circulation, a blower for tank aeration, and electrical panels controlling all equipment. An automatic feeder and water monitoring system are also present. The adjacent feed room stores shrimp feed in an air-conditioned, secure environment. Shrimp are started on brine shrimp, then high-protein fine feed, transitioning to larger food pellets (1.5mm then 2.4mm) as they grow until harvest.
Shrimp are sourced as 'post larvae' (PL10, 10 days old) from a hatchery in South Florida. Upon arrival, they undergo a crucial 30-day quarantine period in separate tanks. This allows for observation for mortality or disease signs, preventing the introduction of pathogens into the main production system. Biosecurity extends to daily practices like footbaths at the entrance, designated work clothes, and sterilizing all equipment (nets, scales) used for sampling, to avoid cross-contamination. The cost of a system like this is estimated between 500,000 to 1 million TT dollars, increasing significantly with scale.
The video concludes by briefly touching on future research plans, which involve expanding marine research into alternative energy sources for the system. The host thanks Daniel Robinson for the informative tour and invites viewers to future videos from the Department of Life Sciences.