Camarines Sur: The Bureau of Fisheries and Aquatic Resources in Bicol (BFAR-5) has initiated a series of water quality assessments in the towns of Calabanga and Tinambac following a significant fish kill event that resulted in the loss of approximately 3.5 tons of fish and crustaceans.

According to Philippines News Agency, BFAR-5 spokesperson Rowena Briones, in a phone interview, confirmed that the fish kill occurred on May 23 and 24, impacting various areas including Kawit Island, Cagsao, Calabanga, Old and New Caaluan, Sogod, Mananao, and Tinambac. The estimated damage cost is around PHP512,500. Local government units are currently assisting the affected fisherfolk while BFAR continues to monitor the situation through regular water quality assessments and field surveillance.

Briones mentioned that fish samples have been collected and are undergoing laboratory examination at BFAR's Central Office in Manila to determine the potential causes of the fish kill. Initial test results suggest that deteriorated water quality parameters, such as low levels of dissolved oxygen ranging from 0.18 to 2.07 ppm, are likely contributing factors. These levels fall far below the ideal threshold of 5 ppm. Additionally, hydrogen sulfide levels were found to be between 58.9 and 280 mg/L, exceeding the desirable limit of 0.002 mg/L. High turbidity and ammonia levels have also been noted.

Briones emphasized the need for public, coastal community, and local government unit involvement in the protection and sustainable management of aquatic resources. She urged adherence to fishing regulations and the practice of responsible and sustainable fishing techniques. She also advised against consuming fish affected by the fish kill, although freshly harvested and live fish from the area are deemed safe to eat.

One possible cause of the low dissolved oxygen levels is attributed to the hot weather, which reduces oxygen availability in warmer waters, coupled with increased oxygen demand by marine life. Additionally, sudden rains following hot weather can cause temperature shocks, as heavy rains can stir up sediments, increase turbidity, and cause cold rainwater to sink, thereby reducing oxygen levels further.