P50 million worth of bangus lost in fishkill

By Jennelyn Mondejar

BOLINAO, Pangasinan – An estimated P50 million worth of bangus (milkfish) was lost due to fishkill along the narrow portion of the Cacquiputan Channel between the towns of Anda and Bolinao.

Westly Rosario, interim executive director of the National Fisheries Research and Development Institute and center chief of the Bureau of Fisheries and Aquatic Resources in Dagupan City, said that based on their water sampling Wednesday, the dissolved oxygen (DO) was at 1.7 parts per million (ppm) at surface and about two to three ppm only at the middle depth.

The normal DO for bangus growth is 5 ppm, he said.

When they came here with the BFAR team using high-tech gadgets given by the Norway government for the water sampling, he said the bangus they saw had been dead for several days because their stomachs were already bloated and many were decomposing.
“So the water was already thick and had very foul odor,” he said.

Rosario said the long rains after hot days prior to the problem could have lowered water salinity and caused the death of micro algae.

“As usual the area is good for micro algal bloom because of rich nutrients influenced by aquaculture activities,” he said.

He said when the micro algae suddenly die of sudden decrease in salinity level, DO could have been pulled down to a level the fish cannot tolerate.

This was also aggravated by no tidal action because of neap tide, Rosario said. “So there was no mechanical aeration of the water,” he said.

In 2001, there was a massive fishkill in this town and about P300 million worth of bangus was lost.

Prior to the latest fishkill here which started Sunday, there was a similar incident in 2008 wherein losses also reached millions of pesos.

Rosario observed that there were more fish cages built in the area. He said when the total weight of stocks is big, there is also huge consumption of oxygen among the fishes.

One fish cage yields from 17 to 20 tons of bangus which is about 40,000 pieces and commercial feeds consumption is about 2,000 bags for the growing period of about 120 days, he said.

He advised bangus growers to observe “no new stocking of bangus” for at least a month to enable the waters to recover.