Giant trevally fish grows tremendously. The good news is, the hatchery and rearing technologies have already been mastered

Picture: Giant Trevally / Caranx sp fish,  Source: wikipedia.id

Giant trevally fish, or what is known as Bubara fish in Maluku language, is one type of pelagic fish. This highly sought fish lives in shallow coastal waters and coral reefs.

“In 2007, some seafood restaurants sold a 300-400gram giant trevally for IDR 75,000 / kg.” Said the person in charge of the Marine Cultivation Workshop from the Fishery Training and Socialization Association (BPPP) of Ambon, Lexon. H. J. Tingloy.

Picture: Lexon. H.J. Tingloy. Source: bp3ambon-kkp.org

Lexon stated that this carangidae family is one type of pelagic fish with important economic value. Fish from this family are highly sought by the people of Maluku, especially the giant trevally.

In inner part of Ambon Bay, these fish undergo 2-3 cycles a year, and are often caught by fishermen around the bay using fishing gears, gill net, beach net, bubu fish trap, and bagan fish trap.

Although carangidae family fish are pelagic fish, Lexon said that in actuality, this type of fish can be cultivated in floating marine cages. Giant trevally fish has several advantages; it does not require intensive care like grouper fish, it is resistant against diseases, it can adapt to extreme water quality changes, and it eats a lot hence resulting in relatively fast growth.

Giant trevally has considerably good prospect to be cultivated in marine cages. One of the advantages of cultivating fish in marine cage is that the harvest time can be adjusted to the fish market price in order to get a higher selling price.

The development of giant trevally fish inside marine cage in Indonesia especially Maluku and Papua is highly strategic due to the natural resources there that are still productive, as well as for economical factor which can increase the income and welfare of the fish cultivator society.

In order to support the success of this project, decent cultivation technology and management are necessary. Currently, giant trevally cultivation attempts are being done in BPBL Ambon in a marine cultivation development program, starting from larva nurturing in a controlled tub, to the rearing in marine cages, and until a more productive harvest.

This step taken by BPBL Ambon is apparently inline with the Maluku government program which aims to make inner Kotania Bay into a Cultivation Minneapolitan area in West Seram District. The West Seram district of Maluku Province is one of the location for cultivation region development.

Lexon stated, currently the prospect of giant trevally cultivation is deemed highly profitable due to high domestic demands. This is especially because giant trevally fish is known to have faster rearing period (5-6 months).

He continued, the giant trevally fish yield is mostly purchased directly by seafood restaurants across Ambon island and its surroundings, and for household consumptions. The average giant trevally fish yield is 3-5 tons per year.

“Giant trevally fish is still distributed mainly locally. Purchases from other regions are still small in capacity. The price per kg for giant trevally fish is relatively high, which is around IDR 75,000/kg,” Lexon said.

Within the Ambon island itself, the demands for giant trevally fish from restaurants are still not fully met and giant trevally fish stock is still considered low. This is because the favorite food of the people of Ambon island is fish.

Picture: Head of BPBL Ambon, Tinggal Hermawan Source: Malukupost.com

The head of BPBL Ambon, Tinggal Hermawan, stated, “BPBL Ambon is able to independently supply giant trevally seeds. The production capacity per cycle is 50,000 fish, with 3-month production period from hatchery until it reaches the size of 5 cm,”

The development of giant trevally fish production in BPBL Ambon is stable, with parent fish that can regularly spawn with the help of hormonal injections.

“The target of BPBL Ambon for giant trevally in 2018 is to increase production to a minimum of 600,000 pieces per year, with improvements in rearing technologies, from the procedures and utilization of modern technology, to creating seeds with faster growth rate,” he said.

The markets for giant trevally fish seed are the city of Ambon, Tual, Ternate, Jakarta, as well as Central Maluku and West Seram District. The main market is still the restaurants located in Ambon.

“There are still no companies who accommodate the giant trevally fish cultivation yield because there is even not enough stock to meet the demands from restaurants,” Tinggal said.

The Rearing of Giant Trevally Fish

Picture: Coordinator of Parent Fish Production Division of BPBL Ambon, Rochman Subiyanto Source: kkp.go.id

Similar with Tinggal, the Coordinator of Parent Fish Production Division of BPBL Ambon, Rochman Subiyanto, stated, “The prospect for giant trevally development attempts is very promising to fulfill the local demand for consumption size giant trevally fish. The number of restaurants all across Ambon is high, and the people’s interest in fish consumption is considerably good.”

This consumption size fish stock limitation urges BPBL Ambon to keep innovating in finding solution in the form of simple cultivation technology application, which is applicable by the cultivator society in general.

Rochman continued, the trials are continuously conducted through engineering activities such as assessments for ideal distribution density, feed combination, or other treatments, which in the end are expected to lower the FCR value and increase the fish’ survival rate. This way, the consumption size fish production value will increase, hence increasing profit economically for the cultivators.

Picture: BPBL Ambon Marine Consumption Fish Seed Distribution in Floating Marine Cage Aquatec Source: bpblambon-kkp.org

The giant trevally fish rearing cultivation technology conducted by BPBL Ambon has been done using Aquatec floating marine cages. 178 plots of Aquatec marine cage has been used by BPBL Ambon since 2013. It is chosen due to its easy maintenance and environmental friendliness, as well as its excellent durability against waves and weather. Marine cage has a size of 3x3x3m/plot. Distribution density is approximately 500-750 fish/plot with rearing period between 4-6 months and harvest size between 250-300 grams/fish. The current production of cultivated giant trevally fish in Ambon is still not enough to cover the local market demand. Therefore, additional marine cages are required.
“One of the efforts taken to increase fish production yield in marine cages is to enrich the feed with additional vitamins or food supplements containing Omega-3 fatty acid. This is done routinely from week to week.

The common obstacle in giant trevally fish cultivation in marine cages is the parameter changes or fluctuations of water quality due to heavy rainfall in rainy seasons. This triggers a decrease of DO and water salinity. The water even becomes murky due to the high amount of sediments that got carried into the waters. In addition, rainy season also means bigger waves and extreme weather condition. Fortunately, Aquatec marine cage has good durability against such weather condition, hence the cultivation activities can go on smoothly.

Picture: Aquatec Floating Marine Cage and Floating Houses

Sudden weather change sometimes also causes an increase in certain microalgae growth (blooming) which can cause stress and death in fish.

“The tips and tricks in cultivation are to remain diligent, persistent, patient, discipline and open hearted. Fish cultivation business has considerably high risks since it involves living organisms. Consistent attitude is necessary in doing this cultivation business,” he added.

Further, Rochman said, “coaching for cultivators, synergizing with all related institutions, fishery socialization, and fishery optimization in field technique coaching, providing information on newest technology for the cultivators according to the predetermined cultivation standard.”

This coaching is done to manage the cultivators and strengthen institutional groups in order to achieve a goal synchronization within cultivator groups to do fish cultivation business, which is expected to gain an increase of income.

Giant trevally fish cultivation must continually increase and promoted nationally. This requires effort and coordination n socializing and promoting the advantages of giant trevally fish commodity, so that this rearing program can be widely promoted.

This must surely be supported by sufficient seeds availability to supply the giant trevally seed needs for rearing. “To form a solid market or business network, so that information regarding market demands will always be updated all the time, and the need for consumption size giant trevally fish can always be met,” Rochman said.

Picture: Aquatec Extra Butt-fusion Round Floating Marine Cages in Ambon