ANDA, Pangasinan — Thousands of milkfish have been bellying up in this bangus-producing island town since June 4, incurring huge losses to fish farmers here.

The town government, however, refused to call it a fish kill, saying the dying of bangus here was "not massive" and was not caused by poor water quality.

"We call it isolated fish mortality because we had an agreement before that if its a fish kill, there should be low oxygen level, very high or very low salinity, or high ammonia level in the water," said Elizabeth Tomas, this town's municipal agriculturist in an online news conference on June 7.

Tomas said that the fish mortality took place in an aquaculture strip at the mouth of Santa Rita tributary, a water inlet between the villages of Awag and Dolaoan.

"So, last Tuesday, we were surprised to see bangus gasping in that strip of the aquaculture area," said Tomas.

She said that for two days before the bangus deaths, neap tides took place on Sunday and Monday.

During a neap tide, which occurs when the moon is between its fourth and first quarter, the tide level is at its lowest and the water does not flow.

"Then on Monday morning there was a major downpour in the island followed by intermittent rains in the days that followed," Tomas said.

This was not the first time that cultured bangus were found dead in this town.

Since the time aquaculture areas were set up here in 1998, several major fish kills have taken place. The last isolated fish mortality happened in 2019, Tomas said.

She said she could not quantify yet the amount of losses but she quickly added that the affected fish cages were about 125, which, she said is 14 percent of the total number of bangus cages in the island.

However, a resident here who spoke on condition of anonymity, said that bangus growers may have lost "millions" of pesos from the incident.

Anda said that the towns of Bolinao and Sual produces 80 percent of Pangasinan's total bangus production.

Photos and videos posted in the social media showed dead bangus floating inside the cages and fishermen catching those that were still alive.

Tomas said that up to now, operators are still harvesting in that strip of the town's aquaculture area before transporting them to major markets like Dagupan City in Pangasinan and Malabon in Metro Manila.

She also said that she was informed that fish mortality was also reported in aquaculture areas outside Pangasinan, but this could not be immediately independently verified.

Meanwhile, the Bolinao Disaster Risk Reduction and Management Office (BDRRMO) clarified that no fish mortality have been reported in Bolinao.

In a statement posted on social media, BDRRMO said that it has verified with local authorities and fishery experts that Bolinao has not been affected by the fish kill incidents. The town shares a body of water with Anda.

"As of today (Friday), [there is] no verified reports of fisk kill in Bolinao, Pangasinan. Our bangus supply remains healthy and unaffected. The water quality and fishery conditions in our area continue to meet all safety and health standards.," the statement said.

"We urge everyone to rely on verified information and refrain from spreading unconfirmed reports. Misinformation can cause unnecessary panic and harm to our local economy and the livelihood of our fish farmers," the statement added.