PHL waters being taken over by invasive fish 

By Brontë H. Lacsamana  

Over the last decade, fisherfolk operating in freshwater lakes and rivers have noticed a shift in the contents of their catch, according to environmental group Best Alternatives.  

Native fish like biya (gobies), ayungin (silver perch), martiniko (climbing perch), and ulang (freshwater shrimp) have grown scarcer while species alien to the Philippines such as knifefish from Indochina, blackchin tilapia from Africa, janitor fish from the Americas, and cream dory from other parts of Asia, have multiplied in inland waters.  

“Our native fish are dying a slow, silent death because they’re quietly being eaten by invasive fish every minute, every second. It’s happening now,” said Gregory Paul “Gregg” H. Yan, founder of the Best Alternatives campaign, in an interview with BusinessWorld.  

He shared that fisherfolk along Marikina River observed an abundance of Nile tilapia, janitor fish, knifefish, and blackchin tilapia (dubbed Gloria or Arroyo due to the black moles on their faces) after heavy rains this July.  

(When it rains, ponds, lakes, and other bodies of water in areas like Rizal and Laguna overflow, allowing fish to escape into the Marikina and Pasig rivers. Fisherfolk, knowing this, go there while water levels are elevated.)  

Only the kanduli, a type of brackish water catfish, remained plentiful among the numerous native species that used to roam the river.  

“They said there’s regularly a lot of kanduli, but that’s almost the only native species left,” he said. “Still, they’re just happy to have a catch because, when you get a 20-kilogram cream dory, siyempre tingin nila biyaya (of course they see it as a blessing).”  

ALIENS EVERYWHERE
In 2011, two years after Typhoon Ondoy, fisherfolk in the Laguna Lake area reported an alarming presence of the ornamental knifefish in the lake, which was traced back to their possible escape from aquaculture ponds during the typhoon. BFAR, after conducting surveys, declared it an infestation of invasive alien species (IAS) in the lake.  

“By 2012, nearly half of fishermen in the area were affected by this, with knifefish comprising a large chunk of their catch,” said Romualdo M. Pol, officer-in-charge at BFAR’s National Inland Fisheries Technology Center (NIFTC), told BusinessWorld. 

He added that NIFTC analyzed the gut contents of the knifefish, finding that around 32% were small fish heads and tails and about 29% were scales and eyes of kanduli, meaning the lake’s native species were indeed being eaten by the IAS. The sad part was, knifefish weren’t appealing to fish markets and were often released back into waters, where they would continue their reign of terror.  

The worst-case scenario, according to Mr. Yan of Best Alternatives, is similar to what happened to Lake Victoria in Africa, where the Nile perch was introduced to the lake to boost productivity, eventually wiping out 60% of its native cichlids. There’s also a local example, unfortunately — Lake Lanao in December 2020 saw 15 of the 17 freshwater fish endemic to the lake go extinct due to invasive species that altered the ecosystem.  

To combat extinction of species in Laguna Lake, BFAR-NIFTC enacted multiple initiatives, from the development of a prototype electro-fishing gadget to stop eggs from hatching to a buy-back scheme that mobilizes fisherfolk to catch knifefish for at least P20 per kilo until they are consumed to depletion, said Mr. Pol.   

He added that the catch is usually processed into fishmeal feed for farm animals as well as value added products like hotdog, fishball, kikiam, and siomai, which they also teach affected fisherfolk to do through livelihood programs. During the pandemic, these have unfortunately been hindered by restrictions.   

Fisherfolk also caught much less, unable to go out in lockdowns, resulting in a drop to around 900,000 knifefish caught in 2020 from 1.9M in 2019, reported Mr. Pol.  

Meanwhile, the Balik ang Sigla sa Ilog at mga Lawa (BASIL) program, launched by BFAR in 2017, has been working on propagating native freshwater species like biya, ayungin, martiniko, ulang, and kanduli to replace the invasive ones being retrieved.  

In addition to collaborating with the Department of Science and Technology (DOST) and University of the Philippines Los Banos (UPLB) for studies on the population dynamics and control assessment of knifefish in Laguna Lake, BFAR-NIFTC said that they’ve been sharing their native species repopulation methods and technologies to a network of regional government hatcheries, to replicate their pilot efforts nationwide.  

SUSTAINABLE BUT EXPENSIVE
Best Alternatives, meanwhile, has put forward transitioning into the farming of local fish species — a long-term objective they’re looking into with European research firm VB Consultancy.   

“We’re trying to convince government and businesses that instead of farming invasive tilapia and cream dory, we should invest in the farming of high-value local fish species like ludong (which is expensive at P5,000 per kilo). It’s a type of mullet, a very common fish, just like how the maliputo and tawilis in Taal Lake are really nothing more than freshwater sardines, which can be marketed well,” said Mr. Yan.  

He cited their advantages: being better adapted to local conditions, resilient to diseases in this part of the world, and profitable for fish farmers who can earn up to P5,000 per kilo of ludong compared to at least P15 per kilo for knifefish and about P80 for tilapia.  

Mr. Pol of BFAR-NIFTC echoed this sentiment, adding that culturing these fishes in aquaculture facilities could eventually lead to more affordable prices once the population grows, since large ayungin currently reach up to P600 a kilo.   

“If we embrace the technologies now, there’s potential for profit, locally and in export markets. Most people have this idea that, to be sustainable, you have to let go of profitability. That’s not true. You can be profitable by farming the right species and you can bring back native fish in the country,” said Mr. Yan.