ONE PARTICULAR problem that minimizes the growth of productivity in Laguna de Bay is the proliferation of knifefish.
The knifefish, known scientifically as Chitala ornata, has been described as “invasive” because its ability to prey on native and economically important species has led to reduced catches, particularly of tilapia, both in open waters and aquaculture cages.
Knifefish has been identified as nocturnal and usually cruise during the twilight hours.
It usually hunts live prey and will try any fish that can fit into its mouth.
It was learned that a young knifefish usually schools near water logs and plants for security, where more mature specimens usually become territorial and eventually become loners.
This kind of fish can also breathe air to survive in stagnant waters and little oxygen, and usually are found in lakes, swamps, and rivers.
In its effort to curb the growth of knifefish population in the lake, the Philippine Council for Agriculture, Aquatic and Natural Research and Development of the Department of Science and Technology (DOST-PCAARRD) is funding a Research and Development (R&D) Program to help keep the population of the invasive knifefish in a minimal level.
The program, which has been titled “Assessment and implementation of control and management strategies for the invasive knifefish in Laguna de Bay,” aims to provide analytical tools and data to improve the effectiveness of current and continuing initiatives to suppress the population of knifefish.
It is being implemented under the leadership of Dr. Ma. Vivian Camacho of the University of the Philippines Los Banos-Limnological Research Station (UPLB-LRS) with a grant of P4.98 million from PCAARRD.
The program has officially started with an inception meeting held at UPLB-LRS.
As its main strategy, the program will look at the migration and aggregation patterns of adult and juvenile knifefish to confirm site fidelity or the tendency of the fish to stay close to its “home range.”
According to Camacho, movement patterns of the fish will be traced through the release of tagged fish in open waters.
This mark-release-capture technique will help in locating knifefish populations.
It will also help determine the risk of knifefish invasion in the designated fish sanctuary in Laguna de Bay.
Tagged fish will be released in at least six sites in the lake and will be monitored in coordination with the Fisheries and Aquatic Resources Management Councils and the Bureau of Fisheries and Aquatic Resources (BFAR).
Lakeside bulletins will be installed to alert fishermen on the catching and release of tagged fish.
At schooling stage, young knifefish can easily be harvested and as such, prevented from reaching maturity.
Towards the end of the project, the most efficient fishing gears and optimal fishing techniques for catching knifefish will be identified.
PCAARRD had previously funded a research on the distribution, reproductive biology, and prey composition of knifefish.
Results of previous studies confirmed that Laguna de Bay is an ideal place for knifefish to breed and propagate.
As such there is a need to continue research on methods for its effective control./PN
