The department was responding after a TikTok video clip of the incident went viral among netizens.
More than 8,000 kilograms of chacunda gizzard shad washed ashore on Saturday evening. Chonburi officials subsequently swept the fish away from the beach.
The video clip had triggered concerns among tourists on whether the incident was caused by a change in sea current or wastewater.
However, the department clarified that the incident was a result of a fishing boat's net being damaged. It added that the seawater quality is normal.
"A large school of chacunda gizzard shad can be found during this time," the department said
The department said a large school of chacunda gizzard shad can generate a large sum of income for locals, adding that the incident was proof of the plentiful resources in the seas off Thailand.
It also urged people to preserve the coastal and marine resources.
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