TILAPIA EXPANSION IN JAVA SEA
Tilapia ( Oreochromis niloticus ) is one of the leading commodities of freshwater fisheries in Indonesia. Indonesia is the largest supplier after China and India. This fish has a fast growth, disease resistance, easy to breed, tolerant of temperature and salt content, making it excellent for fish farmers. The Tilapia meet the people’s need for animal protein because it is relatively affordable. However, the intensification of Tilapia aquaculture brings negative effect that are rarely considered. It has the potential to become invasive fish.
Tilapia is included in the list of 10 invasive animals in the world whose distribution is evenly distributed throughout the continents except for Antarctica. In many countries such as Brazil, Australia, and the United States, tilapia is a plague because of its uncontrolled population. Even in Africa, many countries have complained about the existence of tilapia that are far from their original habitat as they invading new areas. In Indonesia, Tilapia was imported from Taiwan in 1960s with the hope of being able to become a new commodity of freshwater fisheries. But in reality, tilapia fish spread uncontrolled to various parts of Indonesia. One of the areas in Indonesia experiencing the worst impacts of tilapia is lakes in the deep Sulawesi which have a lot of endemic fish and shrimp. According to the observations of many researchers, tilapia fish compete with the declining endemic aquatic fish in the region.
In the mainland of Sumatra, Kalimantan, Java, Sulawesi and Papua, the main cause of the massive distribution of tilapia to public waters is a poor way of fish farming. Tilapia fish is deliberately thrown into rivers or lakes because they are considered no longer productive, and these actions make tilapia breed outside the controlled breeding pond. It is also exacerbated by ignorance from the related agencies in restocking fish in nature. Many of them even release Tilapia into public waters in the hope that this fish can become the source of population livelihood, even though this action is fatal. There are different objectives and interests between the food and conservation sectors. The food sector considers Tilapia will provide cheap fish-based animal protein, however, from a fish conservation perspective this is detrimental. Besides being able to get rid of local fish, Tilapia can also be a vector of disease for other aquatic organisms.
Tilapia is almost widespread throughout the main islands of Indonesia. This fact inspired Universitas Airlangga researchers from the Faculty of Fisheries and Marine to collaborate with the Faculty of Science and Technology to conduct studies in remote areas, especially in the conservation islands in Java Sea to know whether the conservation islands have been invaded by Tilapia or are still sterile from the invasive fish. The result showed that Tilapia is found in Lake Kastoba, a volcanic lake located in the middle of Bawean Island, and the second Tilapia in the Mangrove region of Kangean Island. It is not known exactly how Tilapia can enter the conservation area, but it is most likely done by people who do not know that Tilapia should not be released to any place. Even though they have tolerance to salt content, it is unlikely that Tilapia fish will migrate from one island to another. The only possibility is from human intervention.
The expansion of Tilapia in the Java Sea may reach other small islands such as Masalembo and Masakambing islands. Therefore a thorough study needs to be carried out to facilitate monitoring because in principle the conservation area is an area that should be protected from invasive foreign organisms.
Main reference: Hasan V, Mukti AT, Putranto TWC (2019) Range expansion of the invasive tilapia Oreochromis niloticus (Perciformes: Cichlidae) in Java Sea and first record for Kangean Island, Madura, East Java, IndonesiaEco. Env & Cons. 25 (July Suppl. Issue): S187-S189.
Faculty of Fisheries and Marine