Sri Lanka is well known for its rich marine life; many locals and foreigners alike gather from far and wide just for a mere glimpse of the diverse range of aquamarine animals that thrive in our seas.
A 2020 conservation assessment of Sri Lanka’s freshwater fish has come up with a total of 139 species, out of which 61 are found nowhere else on Earth. The list is part of the International Union for Conservation of Nature Red List, which is valid from the years 2020-2022. The assessment showed that 74% of endemic freshwater fish are threatened with extinction: 12 are critically endangered, 24 endangered, and nine vulnerable.
Many of Sri Lanka’s freshwater fish groups have undergone significant changes and the new study sheds much-needed light on their taxonomic diversity. About 28% of Sri Lanka’s land area has been declared protected areas, managed either by the Department of Wildlife Conservation (DWC) or the Forest Department. Most of Sri Lanka’s freshwater fish are found outside protected areas and are thus affected directly by all the major drivers of biodiversity loss, such as habitat loss and degradation, overexploitation, pollution, invasive alien species, and climate change.
In conversation with Sajeewa Chamikara of the Movement for Land and Agricultural Reform (MONLAR), he explained that Sri Lanka’s freshwater fish species are currently in danger of extinction due to the use of agrochemicals, habitat destruction, and the export of freshwater fish found in the natural environment. He went on to observe that habitat destruction is one of the main reasons for the freshwater fish species facing this situation, in various ways. “Of these, small hydropower projects have been identified as a major factor in the destruction of freshwater fish habitats in the wet and intermediate zone to date. Small hydroelectric power plants completely destroy freshwater fish habitats by drying up large areas of streams, while small hydropower projects have caused some streams to dry up completely within an area of one kilometre to about five kilometres,” he informed. Furthermore, we learnt that in 1996, about 120 small hydropower plants were installed in wet and intermediate zones, generating about 220 megawatts of electricity. “It is 9% of the total power generation in the country,” explained Chamikara, but, he added that the damage it has done to many river ecosystems, the local biodiversity, and humans, is not insignificant.
On the other hand, when speaking to marine scientist Rohan Pethiyagoda, he said that he has no knowledge of there being an especially urgent problem when it comes to threatened fishes: “As far as I know, there are no species that are in imminent danger of extinction in Sri Lanka.”
He further explained that some species might be naturally rare, so we have no way of knowing whether they are declining in population or not, because there is a lack of long-term population monitoring. “If you think about it, in the case of elephants, every time the wildlife department takes a count, there is a difference of thousands,” Pethiyagoda observed. So in terms of the fishes, especially in terms of rare fish, it is very difficult to know how many might be declining. “It is a totally unknown area, and very little research has actually been done about this,” he commented.
Conserving freshwater fish
The 2020 freshwater fish red list assessment includes recommendations for conservation. One is to launch islandwide systematic surveys of freshwater fish, as recent evolutionary studies show there are species yet to be described and that taxonomic clarity is needed for several already described species.
Another recommendation is to conduct population assessments of at least the critically endangered species. The recent evaluation process revealed that some nationally threatened species with a wide distribution range could not be listed under any of the IUCN threat categories.
Development of conservation action plans have been proposed for the threatened fish species found only in Sri Lanka and to evaluate the feasibility of ex-situ conservation, where breeding of critically endangered species occurs.
