Fishery development: cage-net aquaculture feeds without waste, and underwater monitoring systems can prevent fish escapes
The Fisheries Research Institute's yellowfin tuna farming project has temporarily come to a close. Although there were results, operators are still watching and waiting. The reality is harsh: the problem faced is the market, because the price of yellowfin tuna is not high enough. Before consumer impressions of yellowfin tuna can be turned around, operators' willingness to farm it is low. Still, the 4-year research project did produce results. The underwater leftover-feed monitoring system designed for the research can be applied to cage-net aquaculture management for other fish species and has already been technology-transferred to 2 aquaculture operators. This system will also be exhibited at this year's Taiwan International Fisheries and Seafood Show. It can help cage-net aquaculture operators monitor the remaining condition of feed and precisely control feeding amounts to save feed costs, and it can also monitor the health condition of the farmed organisms.
Wu Long-jing, director of the Coastal and Offshore Resources Research Center of the Fisheries Research Institute under the Council of Agriculture, said that in order to study yellowfin tuna farming, sea cages were leased from fishermen. The types of food fed to yellowfin tuna include: mackerel, trevally, Pacific saury, and others, but it was impossible to determine how much feed would let the yellowfin tuna in the cage eat just enough, avoiding putting in too much feed and causing waste. Therefore, an underwater leftover-feed monitoring system was developed. Through this set of software and hardware equipment, 10% of feed costs can be saved.
In fish farming, feed costs account for a very heavy proportion, around 50%, so if 10% of feed expenses can be reduced, it is already very helpful to aquaculture operators. If the feed for cage-net aquaculture is provided in just the right amount, it can also reduce the problem of aquaculture environmental pollution.
Wu Long-jing said that if too much feed is put into offshore cage-net aquaculture, it will create some problems after sinking into the sea. The first is pollution of the environment. Although the fish are farmed in seawater, within the cage-net area, uneaten food can still sink to the bottom and cause the aquaculture environment to be polluted. The second is the cost problem. Feed has always been the main cost burden of aquaculture fisheries. It is best for the feed to be eaten completely so that money is not wasted. Therefore, the more precisely the demand for feed can be controlled, the more aquaculture efficiency can be improved.
The underwater leftover-feed monitoring system developed by the Fisheries Research Institute includes: surface and underwater image monitors, as well as software. Through the internet, feed feeding and fish feeding conditions are transmitted directly to the boat and the onshore office. Onshore personnel can grasp in real time how the fish are eating the feed and can adjust the feeding amount accordingly. It is estimated that each cage net can save 200,000 yuan in feed expenses per year.
The monitoring system also has an incidental benefit: it can be used to observe the activity and health condition of the farmed organisms. At present, aquaculture operators have already applied it to cobia cage-net monitoring, which can promptly discover whether the cage net is damaged and avoid fish escapes, improving overall aquaculture efficiency. The Fisheries Research Institute authorizes operators to use the underwater leftover-feed monitoring system and can collect 150,000 yuan in royalties every 2 years. It will also be exhibited at the 2019 Taiwan International Fisheries and Seafood Show held in Kaohsiung in late September.
From left to right in the image: offshore cage nets, yellowfin tuna farmed by the Fisheries Research Institute in offshore cage nets, and images transmitted in real time by the underwater leftover-feed monitoring system