Dagupan milkfish susceptible to ‘thermal shock’ due to summer rains

DAGUPAN CITY — Milkfish growers here had been alerted amid the seemingly abnormal weather condition prevailing these days when a sudden downpour comes after a hot summer day at a time when the temperature usually reaches above 40 degrees centigrade.

City Agriculture Officer Emma Molina, however, reported that despite this abnormal situation that occurred since after the Bangus Festival ended on May 6, no force harvesting was noted in Dagupan yet.

Aquaculture scientists dubbed this kind of situation abnormal, which is a bane to fish in captivity and likely to bring thermal shock, leading to mass fish kill, Molina said.

She said that nature was kind though as the sudden abrupt rains always would come in the afternoon or early evening when water from the sea was entering the rivers and into the fishponds because of high tide.

With the colder water from the sea entering the fishponds, no thermal shock on the fish has ever occurred, said Molina. She, however, called on the fish farmers to open the gates of their ponds once high tide comes to let the colder water comes in.

In this hot weather, Molina called on fishpond owners and their caretakers to be always observant always.

She told them to watch out for signs of thermal shock such as if the fish were reaching the surface of the water with their nostrils first.

This is also a sign of lack of dissolved oxygen in the water so there is a need to undertake some interventions in order to save the fish, she added.

When these signs come, force harvesting is necessary if fish farmers do not want to incur more losses which they surely will if the fish will die in the water, she added.

She said they have already started advising local fish farmers to do something to prevent the effect of thermal shock because of the prevailing abnormal weather.

Molina said the most vulnerable to thermal shock would be the bigger milkfish or those already within marketable sizes.

She also admitted that during hot weather condition, the growth of milkfish was usually slow. PNA – northboundasia.com