AQUATEC HDPE FLOATING MARINE CAGES SUPPORTS MARINE CULTIVATION
The presence of floating marine cages (KJA) is vital in assisting the work and function of the Lampung Marine Cultivated Fisheries Major Association (BBPBL). This is because most cultivation related activities are performed in marine water. Therefore, a strong durable marine cage is necessary.
According to the Head of BBPBL Lampung, Mimid Abdul Hamid, BBPBL is currently cultivating some consumable fish, such as the duck grouper, tiger grouper, white snapper, red snapper, snub-nosed pompano, and cobia. They also cultivate fish for aquarium display such as Nemo ocelaris, Nemo percula, Blue devil, sea horse, and sea cucumber. They are also developing a pattern for vanname shrimp cultivation in marina marine cage. “But of all those types of fish, the top commodities are white snapper, cobia, and snub-nosed pompano,” said Mimid when receiving Trobos Aqua at marine cage BBPBL Lampung in Hurun Bay recently.
Currently the association located in Hanura village, Pandan Bay sub-district, Pesawaran district, Lampung, has succeeded in producing white snapper, cobia, and snub-nosed pompano in bulk. It has high growth rate and the consumption cost is affordable by the community, hence giving it good market potential worth developing. Moreover, technological dissemination and den farm activities have been implemented among fish cultivator groups in Lampung, Seribu Islands, NTT, Bangka-Belitung, and West Sumatera.
At BBPBL, the consumable white snapper production now reaches 1,400 kg per cycle (about 6 months) from the seeds of 3,500 fish, with SR (Survival Rate) of 80%. “So the number of fish which manage to survive is 2,800 fish with average weight of 0.5 kg. To produce a fish with this weight, it requires artificial feed of 2.8 tons with FCR of 1 to 2,” he said.
For cobia fish, 2,700 kg per cycle (about 6 months) is produced from a seed of 1,500 fish with 60% SR. Meaning the number of fish which survives reaches 900 with average weight of 3 kg. The nourishment of cobia requires 5.4 tons of food with 1:2 FCR.
Meanwhile for snub-nosed pompano, from a seed of 7,000 fish and 80% SR, 5,600 fish are produced with average weight of 0.5 kg per fish. Hence the harvest reaches 2,800 kg. The amount of feeds required is 5.6 tons with an FCR of 1:2.
“In order to reach a total production per type of fish as stated above, BBPBL has followed the Proper Cultivation of Fisheries (CBIB) guidelines. The seeds are also in accordance to the good quality SNI standard,” said the Head of BBPBL who formerly worked at the Freshwater Cultivation Association in Jambi.
Cultivation Phases and Methods
More about the technical aspects of cultivation, Mimid explained, of the three steps of cultivation, which are nursery, grouping, and rearing, almost all of them are done at sea. Only the nursery step is done on land using a controlled tank, or at sea by using a 1x1x1.5 m nets. To lower the cost, some nursery is now also done in a marine cage because it does not require water wheel and pump.
During nursery, the seeds are given artificial feeds with additional vitamins and multivitamins. Nursery within nets usually has 150 to 200 fish per net and these fish are reared for 1.5 months.
The next step is the grouping of seeds from the nursery, which is done at sea using nets with mesh size of 0.75 to 1 inch. Here, the seeds are kept for 1.5 months in nets with the size of 1x1x1.5 m with initial population of 100-150 fish per net.
The final step of fish cultivation is the rearing of seeds that have passed through the grouping process. The rearing process is done in marine cage in Hurun Bay, Pesawaran District, with a net size of 3x3x3 m. Initially, the population was set at 20 fish / m3, then at the third month, it is reduced to 15 fish / m3.
In the marine cage, the fish are kept for 5-6 months until it is time for selective harvest for fish weighing 500 grams to 1 kg each. “Fish with that weight average can be sold at high price in the market,” he said.
For fish feeds, they use commercial pellets with a size ranging from 3 mm to 9 mm, once or twice a day. The dose is 1.5 to 3 percent per day from the total biomass of the reared fish.
Modern marine cage
At the time being, BBPBL owns 120 modern KJA holes made from High Density Polyethylene (HDPE) from Aquatec. The pipes which are made from Polyethylene are assembled using grade 304 stainless steel bolts, and equipped with paddings to maintain flexibility against 2 m tidal wave.
According to Mimid, there are some advantages from using HDPE floating marine cages. One of which is that it uses knotless nets which minimizes the risk of the fish scrubbing their bodies against the side of the nets. Also, the HDPE material lasts longer (15 years) and the material is environmentally friendly. The price is also not too high, which is IDR 35 million per square.
Meanwhile, conventional marine cage uses knotted nets, which makes it less flexible. The wood and Styrofoam materials could result in loggings and a not so environmentally friendly Styrofoam. Not to mention, the technical lifetime is also shorter, which is 5-years maximum. “The only thing is that we have to admit that conventional marine cage is cheaper. It only costs IDR 7 million per hole with a size of 3 by 3 meters,” he said.
Although the cost is higher, the fish productivity in HDPE marine cage with net size of 3x3x3 meters can reach 350 fish, totaling to 175 kg with average weight of 500 grams per fish when harvested.
The marine cage manufactured by Aquatec, according to the Head of the Association, has good quality and a considerably durable construction to withstand tidal waves and is easy to handle. The Aquatec marine cage which is made from pipes is easier to clean from organisms which sticks to the floating marine cages, such as wild mussels.