ASEAN member states have identified 112 invasive alien species affecting their forests, agriculture, and aquatic ecosystems.
GROCERIES and supermarkets teem with fish like cream dory and tilapia which are not native to our waters but are considered invasive species.
Indigenous river fish species like biya (bottom-dwelling gobies), spear-shaped halfbeaks called kasuswit, climbing perch called martiniko which can briefly crawl on land to reach the next muddy pool and colorful gouramis and other fish are now being replaced rapidly by these invasive species.
Bad news
Today, invasive fish have taken over the river. Hailing mostly from Africa, South America and Indochina, they have successfully adapted to Philippine waterways – which is bad news for our native fish, recalled Gregg Yan, an environmentalist who founded Best Alternatives.
“During my last trip (to the Marikina river after the long habagat), local fishers caught black chin tilapia (called Gloria or Arroyo because like the former President, the fish have cute little moles on their faces), Nile tilapia, African catfish, janitorfish, pangasius or cream dory, plus smaller fish- like guppies and mollies which eat mosquito larvae,” Yan said.
“These fish have one thing in common – they aren’t native to the Philippines. In fact, the only native fish the fishers caught that day were several kanduli, brackish water catfish usually caught along Manila Bay,” he added.
Disappearing
“Our native fish are slowly disappearing. Sadly, this seems to be the norm and not the exception for many of our rivers and lakes. Even protected biodiversity bastions like Taal Lake, with its unique freshwater sardines called tawilis and trevally called maliputo, have not been spared from the introduction of exotics,” he lamented.
He gave two reasons for such imported species: 1) for food (which gave rise to tilapia farms all over the archipelago) and second the aquarium trade.
“So successful are tilapia at colonizing waterways that most Pinoys now think the ubiquitous fish are native to the country. Newcomers to the country’s aquaculture industry include pangasius, giant catfish from Indochina which are marketed as ‘cream dory’ to make the bland fish sound a bit more delicious,” he explained.
The aquarium trade-- best exemplified by the janitor fish which are now becoming more common in our rivers-- many fish are sold when they are young, cute and still colorful.
As many fish mature though, they lose their bright coloration and grow larger than most fish keepers think.
“Unwilling to kill their beloved grown fish, aquarists sometimes release them in local waterways and hope for the best – not knowing that fish which come from similar climates as the Philippines can survive and even breed in our waters, Yan added.
So now our rivers and lakes host giant knifefish and snakeheads from Indochina, janitorfish from the meandering rivers of the Amazon, plus territorial cichlids from Africa.
What happened in Africa?
In East Africa’s Lake Victoria, the introduction of Nile perch has proven disastrous.
To ‘boost fisheries productivity,’ the predatory fish were introduced to the lake in the 1950s.
Growing over six feet long, they soon preyed on over 100 other fish species, practically wiping out 60 percent of the lake’s native cichlids in what may be the largest vertebrate extinction of the 20th century.
As you read this, thousands of brightly- colored cichlids (one species alone is worth P2,000 apiece, compared to Nile perch which sells for P200 per kilogram) are being eaten hourly. The Philippines has already experienced a similar phenomenon, with at least 15 fish species declared extinct in Lake Lanao.
Not the first time
“This is not the first time we are witnessing the impacts of invasive alien species, which eat or outcompete native species,” says Dr. Theresa Mundita Lim, executive director for the ASEAN Centre for Biodiversity, an intergovernmental body which protects and conserves the ASEAN’s biological diversity.
“While the introduction of invasive alien species like tilapia or pangasius may be perceived as valuable for livelihoods, food production or pest control, science-based assessments should be undertaken to determine if it leads to adverse impacts on the environment and biodiversity. We should ensure that this will not bring more harm in the long run. The extinction of native and edible fish species affects nutrition, food security and dietary diversity. This leads to numerous local, national and regional implications,” adds Lim.
According to the ASEAN Biodiversity Outlook 2, ASEAN member states have identified 112 invasive alien species affecting forests, agriculture, and aquatic ecosystems.
“Given that we have all these introduced species already being considered as economically important and are being used in aquaculture, it is imperative that we focus our research and technology development on the breeding, propagation and culture of our native species like ayungin, tawilis, maliputo, igat and native hito, both for conservation and sustainable aquaculture,” explains Dr. Ma. Rowena Eguia, a geneticist from SEAFDEC/AQD, an international body which promotes sustainable fisheries development in Southeast Asia.
Farming invasive species
Best Alternatives, an NGO based in the Philippines and VB Consultancy, a research firm based in Europe, are working to highlight the dangers of farming invasive species.
Instead of farming potentially invasive foreign fish, the two groups are working to convince governments and private institutions to farm native species instead.
“In addition to conserving genetic diversity, farming native fish has many benefits,” explains Jonah van Beijnen, head of VB Consultancy. “They are often best suited to local climates, giving them better chances of surviving adverse weather effects like storms or droughts. Local species can better resist both disease and parasites. Lastly, they are typically in demand and fetch better prices than invasive fish.”
Institutions like SEAFDEC/AQD, DA-BFAR, DA-NFRDI and the University of the Philippines are already experimenting with rearing and farming ayungin, tawilis, maliputo and other native fish.
Sustaining native species
This is a vital step in protecting and sustainable managing the populations of native fish still thriving in our country’s rivers and lakes.
Biodiversity – once lost – is gone forever. Though people will always pull fish (and the occasional softshell turtle) from the Marikina River and other waterways of the Philippines, there might soon come a time when our beautiful native fish are relegated to the memories of those who used to visit our rivers.
Tags: #biodiversity, #invasivespecies, #aquaculture, #MarikinaRiver