Overcoming yellow-fin tuna deaths inside tanks with larger diameter HDPE floating marine cage

 Speaking of the development of marine cultivation technology in Indonesia, the Main Association of Marine Cultivation Research and Development (BBPPBL) of Gondol Bali is one of the biggest contributors. The technical implementation unit under the Ministry of Maritime and Fisheries Affairs has long been working on the development marine cultivation technology for many different featured export commodities besides shrimp.

Bambang Susanto, the head of BBPPBL Gondol, informed that there is a positive response for certain commodities such as, Grouper Fish, Milkfish and Abalone Shells after applying the developed technology in the community. Other leading commodities such as Lobster, Tuna, and Sea Cucumber are currently under development.

“We continue to develop various export commodities with the existing marine cultivation technology using the facility of HDPE Floating Marine Cages,” said Bambang. He continued, in accordance to the mandate, BBPPBL Gondol continuously try to establish a leading research institute that will provide data, information and technology of marine cultivation.

Cultivation of Tuna

Indonesia is known as the biggest producer of yellow-fin tuna, with a production of 75% from the total yellow-fin tuna in the world. Unfortunately, over fishing has caused the population of tuna spawning in Indonesian water to gradually decrease and even become endangered.

In such situation, the best solution to maintain the existence of yellow-fin tuna is by applying cultivation. Currently BBPPBL Gondol is developing the cultivation for yellow-fin tuna, and has been successful in spawning yellow-fin tuna inside the floating marine cage HDPE.

Gunawan, a researcher on yellow-fin tuna in BBPPBL Gondol, explained how they need to obtain 200 fish of potential seed with size ranging from 0.5 – 1.0 KG from the waters of northern Bali in order to cultivate yellow–fin tuna. After rearing them for one full year, tuna is considered a seed when they reach sizes ranging from 20 – 30 KG.

Inside the floating marine cage, tuna is fed twice a day. Potential seed is given high protein food, decapterus (flying fish) and squid with 1:1 ratio. In addition to the fresh food, they also added 2.5% vitamins.

He further explained that previous process of cultivating tuna was hindered due to the use of concrete seeding containers. Tuna has a characteristic where they have a high cruising power, causing the tuna couples to hit the concrete wall as they chase around during mating season and die. “We hope the usage of Floating Marine Cage HDPE can help make the seeding process go smoother.” said Gunawan.

The Usage of HDPE Floating Marine Cage
 

Gunawan added, in order to deal with the container problem, the research team has now used four units of HDPE cage by Aquatec for tuna cultivation, which are three units 50m diameter buoy with mesh size of 2.5 inches and net depth of 9 m, and one unit 35m diameter buoy. Ananto, the tuna technician in BBPPBL Gondol, added that the research activity of yellow-fin tuna seeding requires a high standard quality floating marine cage.

Furthermore, the reason why BBPPBL Gondol use Aquatec floating marine cage is due to their elasticity and the strength to withstand large waves. In this case, the location for researching the hatchery of yellow-fin tuna in northern Bali waters has considerably high waves.

For the research activity of the yellow-fin tuna seeding, BBPPBL Gondol uses the round cage.

The circular shape is designed to accommodate the natural habitat of yellow-fin tuna as fast swimmers. “Aquatec floating marine cage is very useful in supporting the research and development of cultivation activities from hatchery to nurturing process in BBPPBL Gondol,” said Ananto.

Bambang also explained, after 6 years of using HDPE floating marine cages for research development of marine cultivation, in comparison to using floating marine cages made of bamboo and wood, the result is much more optimal. “Floating marine cages made of wood and bamboo will get moldy and break in a few years, whereas HDPE floating marine cage is more durable and easier to maintain,” said Bambang.

Moreover, besides easy and durable, Aquatec HDPE floating marine cage also comes in different shapes in order to accommodate various cultivations. “We use different shapes of floating marine cage HDPE; square, circular, and octagonal shape. Circular floating marine cage is to cultivate tuna, square is for grouper fish, lobster and other activities, while octagonal shape is for grouper and fish spawn,” said Bambang.

Also, in order to support the development of marine cultivation technology, BBPPBL is currently improving their facilities and infrastructures. BBPPBL Gondol already has facilities such as, cultivation and nursery for larvae, cultivation media for parent fish, hatchery, and a place for cultivating plankton, floating marine cage root blower as source of aeration, sea water pump, food processing laboratory, chemical laboratory, biology laboratory, pathology and biotechnology laboratory, and also cold storage. The infrastructure of BBPPBL Gondol is considerably comprehensive, and is ready to face the challenges of globalization.