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An invasive fish species is threatening the livelihoods of a north-western Sri Lankan village, aggressively consuming traditional fish and shellfish in the Deduru Oya Reservoir.
However, local fishermen are determined to turn this adversity into advantage.
Over the past two years, fishermen have seen a sharp decline in their normal catch, while snakehead fish, previously unknown in Sri Lanka, have appeared in large numbers.
Officials suggest that these fish, which are common in countries such as Thailand and Indonesia, may have arrived as imported ornamental species. It is believed that once they outgrew their tank their owners released them into the body of water.
Dr. Kelam Wijenayake, an academic who researches the species, says the snakehead has no natural predators in the Sri Lankan ecosystem.
The Deduru Oya Reservoir has provided an ideal breeding ground, offering ample food and the absence of threats, allowing their population to flourish unchecked.
They often come to the surface to seek external oxygen, he said, and are only able to survive with enough water to keep them hydrated.
They have sharp teeth, strong jaws and are aggressive eaters, he said, which means their growing presence could harm the local ecosystem that has evolved over millennia.
They are also larger than traditional freshwater fish species. Fisherman Nishant Sujiva Kumara said he once caught a fish weighing 7 kilograms (15 pounds), while the native species he usually catches mostly weigh less than a kilogram.
“Although we had heard about the snakehead fish before, none of us had seen it until an amateur fisherman came and caught it. This was the first time we saw it, because this fish cannot be caught using nets – it has to be caught by fishing,” said Ranjit Kumara, secretary of the fishermen’s association of the area.
“We started fishing in this reservoir in 2016. At that time, we used to catch small prawns and other high-value varieties, but now they have become very rare.”
Authorities organized a fishing competition to try to control the snakehead population, but it was unsuccessful.
However, fishermen hope to turn the threat of invasive species into an opportunity.
Ranjit Kumara proposed that the authorities promote angler tourism as a sustainable control method, which could also provide alternative economic avenues to villagers who are mostly engaged in fishing and farming.
Fisherman Sujeewa Kariyawasam, who produces salted dried fish using invasive species, said that although fresh snakehead fish has relatively little demand in the market, the dried fish made from it is delicious and a popular dish.
“I am working to further develop this business. As demand continues to grow, more snake heads will be caught for production, which in turn will help control the spread of the snake head population.”