Monday, October 15, 2018 01:00 AM    Views : 971by:Mary Charlotte O. Fresco

Local fish vendors selling Katolong (Giuris margaritacea), a dominant introduced species in Lake Lanao. (Photo source: Dr. Sherwin Nacua)

Lake Lanao, Mindanao's most important lake, now faces a serious threat as native fish species once abundant in the lake are now vanishing at an alarming rate, a research funded by NRCP found.

The displacement of these endemic species in the lake is caused by indiscriminate introduction of non-native fish species initially for aquaculture activities to support local livelihood. However, these introduced species have become invasive which directly affected the native ones either "by direct predation or competition," explained Dr. Sherwin Nacua, NRCP researcher based at the Mindanao State University in Marawi, during the NRCP Mindanao Regional Cluster General Membership Assembly and 16th Scientific Conference last October 05, 2018 at Central Mindanao University in Maramag, Bukidnon.

According to the International for Conservation of Nature (IUCN), invasive alien species are plants or animals that are introduced by man, accidentally or intentionally, outside of their national geographic range into an area where they are not naturally present. Invasive alien species are regarded as the second biggest threat to biodiversity worldwide.

Lake Lanao is a globally renowned ecoregion as it is once home to 22 native cyprinid species (belonging to carp and minnows family) first identified from earliest collections in Lake Lanao in 1924 to 1933.  These species are micro-endemic to the lake, which means that they cannot be found elsewhere. The species belong to the genera Barbodes, Mandibularca, Cephalokompsus and Ospatulus and were thought to have evolved from one species the spotted barb(Puntius binotatus)

But from the sample collections conducted by Nacua and research team from May to October 2016 in Lake Lanao, the fish catch of local fishfarmers was now dominated by introduced "alien" species such as "katolong" (Giuris margaritacea), mudfish, catfish, fry goby, tilapia, white goby, and shrimp species. Native species from the Philippines but not in Lake Lanao such arowan and katipa were also found in the fish catch but in very low relative abundance. Worse, there were no Lake Lanao-endemic species that were found during the sampling period, Nacua reported.

Local scientists attributed the disappearance of some 20 species endemic to Lake Lanao and its surrounding plateau to the radical fluctuations of the water level of Lake Lanao, purportedly due to hydroelectric power plants built within the area, and the unregulated introduction of alien species for aquaculture.

The recent rediscovery of two native carp species, Puntius lindog and Puntius tumba, offers a glimpse of hope. Nacua and co-researchers called for putting in place important management strategies and policy that aim to protect and conserve the remaining endemic species.

In response to this need for action, NRCP formulated the Comprehensive Studies on Lake Lanao for Sustainable Development Program with six project components, which commenced in 2015. Nacua's research targeted to assess the Lake Lanao Fishery Resource which includes population survey, reproductive and morphometric characterization of endemic and introduced fish species of Lake Lanao.

The data collected by Nacua and co-researchers will now provide basis for conservation efforts especially of the remaining threatened species. Among the conservation management actions that the researchers are proposing include imposing "closed seasons" for fishing and establishing areas within the lake that are closed for fishing (which is similar to the "no take zones" that were established in marine protected areas by National Scientist Angel Alcala and his colleagues). The baseline measurements of species on the other hand may be used to differentiate and compare between species that need to be closely monitored and sustainably managed.

Biologists and conservationists in the Philippines recognize that the country still lacks comprehensive knowledge on the impact of invasive alien species on livelihood and ecosystem. This research program of NRCP for Lake Lanao will provide bases for important policy recommendations to effectively address and manage this increasingly urgent threat.


S & T Trivia

" The University of the Philippines developed an anti-cough medicine (Ascof) and a diuretic (Releaf) from Philippine herbs lagundi and sambong, respectively, which won a silver in the 1997 International Inventors' Fair in Switzerland. The research papers were organized by Dr. Francis Gomez. "

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