Warming ocean triggers fish kill in Camarines Sur

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LEGAZPI CITY — The warming of the ocean and poor quality of water in Camarines Sur have triggered a series of events where a large number of fishes died.

WATER SAMPLE Personnel of the Bureau of Fisheries and Aquatic Resources in Bicol (BFAR-5) collect water sample in this undated photo in Camarines Sur following reports on fish kill in the wild areas of Kawit Island, Cagsao, Calabanga, Old and New Caaluan, Sogod, Mananao and Tinambac. PHOTO COURTESY OF BFAR-5

Bureau of Fisheries and Aquatic Resources (BFAR) regional spokesman Rowena Briones said BFAR Bicol conducted a water quality assessment in Barangay Cagsao on May 23 and found an increased level of ammonia from the water samples.

However, a follow-up assessment on May 26 in three reported fish kill sites revealed significantly low levels of dissolved oxygen in surface, middle and bottom water samples across all stations, ranging from 0.18 to 2.07 parts per million (ppm), far below the ideal threshold of 5 ppm.

The hydrogen sulfide levels were found to be between 58.9 and 280 milligrams per liter (mg/L), vastly exceeding the desirable limit of 0.002 mg/L. Turbidity and ammonia levels were also notably high. These deteriorated water quality parameters are likely causes of the fish mortality observed in the area, the BFAR said.

These abnormal water conditions resulted in P500,000 worth of fish kill, according to Briones.

Briones said that three episodes of mortality were reported in San Miguel Bay, specifically in Barangay Cagsao in Calabanga, Bagacay in Santa Cruz and Caaluan in Tinambac, all in Camarines Sur.

The fish kill in Calabanga and Tinambac resulted in the loss of approximately 3.5 tons of various fish species and crustaceans on May 23 and 24 with an estimated value of P512,500.

Though the water parameters analyzed can cause detrimental effects to marine species, the collected fish samples during the fish kill incident will still be subjected to laboratory examination as part of the process in determining all possible causes.

The fish kill incident ceased on May 26. However, the BFAR Bicol, in close coordination with the local government units (LGUs) of Calabanga and Tinambac, continues to monitor the affected areas through regular water quality assessments and field surveillance to track environmental conditions, assess ongoing risks and implement timely mitigation measures.

Briones said the situation is alarming because of the test results, the level of dissolved oxygen in the surface, middle and bottom water samples is extremely low from 0.18 to 2.07 ppm, which is lower than the ideal threshold of 5 ppm.

While hydrogen sulfide was between 58.9 and 280 mg/L, which greatly exceeded the limit of 0.002 mg/L. The turbidity and ammonia levels of the water are also high.

"These are 'lethal' or dangerous to marine species. Hot weather generates insufficient oxygen when the water is hot, the sudden rain after hot weather will also be the cause of temperature shock over the sea, especially if the rain is heavy, which agitates the sediments in the seabed and the turbidity increases," she explained.

The causes of high levels of ammonia were organic waste accumulation, runoffs and when oxygen levels are low, breakdown of organic matter results in ammonia buildup.

The ammonia buildup is due to a mixture of decaying debris, marine plants and other organic wastes. They accumulate in the seabed, and ammonia accumulates specifically when the water current is weak. Just like in the part of San Miguel Bay.

"Currently, the monitoring of the area is still ongoing. The fish samples collected will be transported via air cargo today (May 29) to BFAR central office for laboratory analysis," Briones said.

Following the massive fish kills, the Calabanga Fisheries Management Unit urged the public not to eat, pick nor buy the fish found dead in the waters off Calabanga, Camarines Sur, where the fish kills took place for precautionary measures.

BFAR continues tests on water quality

The BFAR-5 said it will continue conducting water quality assessments in two towns in Camarines Sur.

"We are closely coordinating with the local government units. For now, the LGUs are assisting the affected fisherfolk," said Briones, citing the fish kills that occurred in areas of Kawit Island, Cagsao, Calabanga, Old and New Caaluan, Sogod, Mananao and Tinambac.

Briones said the BFAR has already collected fish samples following the incident, which are still undergoing laboratory examination to help determine all possible causes.

"We are awaiting the [final] results, as they have already been submitted to the BFAR Central Office in Manila," she added.

She said initial test results indicated that deteriorated water quality parameters are likely contributing to the observed fish mortality in the area.

Briones urged the public, coastal communities, fisherfolk and LGUs to actively participate in the protection and sustainable management of aquatic resources.

This includes adhering to fishing regulations and practicing responsible and sustainable fishing techniques.

"We recommend that fish affected by the fish kill should not be consumed. However, fish that are freshly harvested and alive in the areas are safe to eat," she added.

WITH REPORTS FROM PNA