02 April 2023
TRIBUNNEWS.COM - Obi island waters are suspected to have been polluted with heavy metal waste. More specifically in the western waters of Obi island, where there are nickel mining activities. However, studies have revealed that fisheries productivity in waters which is administratively located in South Halmahera Regency, North Maluku, is still well maintained.
Several aquatic ecology survey teams that conducted surveys in the surrounding waters of Obi island confirmed their findings about productivity of the waters around Obi island.
The Napoleon team represented by Prof. Dr. Inneke Rumengan, said that fisheries productivity in Obi island waters, in terms of the diversity of reef fish, plankton and macrobenthos, indicates the condition of productive waters, typical of tropical waters in general. In 2015 to 2021, it showed a stable condition of the marine biota community, with no downward trend.
"Our team observed directly by diving, observing the fish species present there. From year to year, the trend is relatively the same. Referring to coral reef fish, there tends to be a slight increase, both in number and type in 2020-2021," said Prof. Inneke.
Based on the observations made by Inneke and her team, they found various variants of fish, both surface fish (pelagic) and bottom fish (demersal). She said that pelagic and demersal fishes from small to large sizes are still abundant in Obi Island waters.
She cited large pelagic fish species in Obi waters, such as cakalang (Katsuwonus pelamis), tongkol batik (Euthynnus affinis) and even larger tuna (Thunnus spp). While demersal fish for consumption, such as grouper (Serranidae), rat grouper (Cromileptes altivelis), and snapper (Lutjanus).
Inneke further explained that fisheries productivity is mainly supported by plankton. Plankton's position in the marine organism food chain is very strategic. As producers of organic materials needed by other organisms, plankton sustain the life of marine biology above them, including fish.
"Our data regarding plankton that we observe from year to year, in terms of abundance and biological index, shows that the water condition is quite productive. If there are many plankton, there will also be many prey organisms. And the plankton becomes fish food," explained Prof. Inneke, who also teaches Planktonology courses at the Faculty of Fisheries and Marine Sciences at Sam Ratulangi University (Unsrat).
In that 6-year period, her team made periodic observations at 29 points. One of them is in the waters of Kawasi, which is located in the west of Obi Island. The results of his observations if averaged from year to year, fisheries productivity in Obi waters is still relatively the same.
Regarding the number of fishermen's fish catches, it usually varies from time to time, depending on fishing gear used and wind season, so it is not appropriate to be used as a benchmark to measure the productivity of a waters.
"If you look at the catch data, it is not necessarily like that, because what is there is not necessarily caught all. It depends on the season and the fishing gear used. So our research (related to fisheries potential in Obi, ed) is more accurate because we observe directly," he explained.
In addition to conducting direct research, her team also conducted survey research by interviewing fishermen in a number of villages on Obi Island. The information explored includes the types of fish caught, the equipment used, and what the fish is used for.
"Fishermen in Kawasi catch fish for their own consumption or hobby. Even if they have excess, they sell it to local traders. The number of fishermen has decreased because most of them have worked in the existing companies, "said Prof. Inneke, explaining the results of survey research conducted in Kawasi Village which is in the village around the Harita Nickel mine.
Another survey team led by Dr. M Janib Achmad, a marine expert from Khairun University (Unkhair) Ternate, also revealed that the Obi Island waters as a whole are fertile waters because they have abundant chlorophyll. Thanks to the maintained productivity, the local community still prefers to be fishermen.
" Obi's waters are fertile because the chlorophyll is abundant, so fishermen continue to be fishermen," explained Janib Achmad, who also serves as Dean of the Faculty of Fisheries and Marine Sciences at Unkhair.
The findings were illustrated in the study "Fish Basket Survey in Kawasi Village and Soligi Village, Obi Island" conducted by his team in 2022. The study results on surveys in two villages around the Harita Nickel mine explained that the distribution with the highest concentration of chlorophyll a was in the northern part of Obi Island, where the surface temperature was relatively warm and made Obi Island fishermen increase as well.
Fisheries productivity in Obi waters is affected by oceanographic factors. These waters lie at the meeting point between the Pacific and Indian oceans. The meeting of the two large oceans is known as the Indonesian Throughflow (Arlindo). This statement was made by Prof. Denny Nugroho Sugianto, a marine expert at the Department of Oceanography, Diponegoro University Semarang.
Prof. Denny further explained the path of Arlindo in Obi waters. According to him, the Arlindo passes through the northern part of Obi through northern Bisa Island, western Obi, and southern part through southern Gamumu Island. This is what makes the productivity of Obi Island waters very high.
According to Prof. Denny, the productivity of Obi Island waters is reflected in the abundance of pelagic fish in the area. "The presence of these fish has a positive impact on fisheries productivity in Indonesia," he said.
"The primary productivity of a waters is closely related to oceanographic conditions that bring nutrients for phytoplankton growth near the sea surface, thus enriching the biomass in the area," said Prof. Denny, who has conducted research in Obi waters.
Furthermore, Arlindo is the movement of water masses from the Pacific Ocean to the Indian Ocean which has a positive impact on the waters it passes through. The meeting of the two oceans' currents becomes a medium for the migration of large pelagic fish, such as tuna and skipjack. These high-value pelagic fish will be found around the waters through which Arlindo passes.
However, utilizing adequate equipment is needed to access the abundance of fisheries productivity in the Arlindo route in Obi waters. Because Arlindo is offshore, it requires a supporting fleet and fishing equipment.
" If it is around the coast, it is utilized by small fishermen. But if we want to have a big potential, it's offshore. Eastern Indonesia is indeed a barn of fish, because of oceanographic processes," he said, advised that Obi's potential marine resources can continue to be preserved.
The marine experts' research results are confirmed by local fishermen in Kawasi Village. Saidi Jouronga (58 years old) said that Kawasi waters are still abundant in fish. He admitted that he is still fishing in waters surrounding the operations of Harita Nickel, a nickel mining and downstream company that has been operating since 2010.
"I only fish near here. From Kawasi to Akelamo. For bigger fish like tuna and skipjack, we have to go to midwater. But if I go too far to the sea, it's too deep and has big waves. I also have to consider my safety," he said.
Using traditional equipment such as fishing rods, he catches between 20-30 kilograms of fish every day. The types of fish also vary. From Giant Trevally or locals call it Bobara, Grouper, Red Snapper to squid. He sells his fish to local traders at prices ranging from IDR 40,000 to IDR 50,000 per kilogram.
"So if anyone says there are no fish in the Kawasi waters, or even if there are fish, they don't want to eat because the water is dirty, that's a big lie. I was born in Kawasi and still catch fish here to this day, so I understand exactly," said Saidi.
Hut Ibrahim (60), a resident of Kawasi Village who also a fisherman, admitted that he is still fishing in Kawasi waters. Like Saidi, Ibrahim fishes using traditional gear. He used the money from fishing to pay for his daily needs and his children's school fees.
*Source : Tribunnews.com