Here’s why an unusual amount of fish have been washing ashore on Hua Hin beach
Fish washing ashore in Hua Hin may be linked to changing coastal water conditions known locally as “nam biat”, a phenomenon that can leave marine life struggling for oxygen.
The seawater at Hua Hin and Khao Takiab beaches turned a murky red on Sunday, 25 October, as large shoals gathered close to shore. Residents and local fishermen arrived with nets and other equipment, while some took small boats offshore to herd fish towards their nets.
The catches included sea catfish, grouper, sole and sand whiting. Residents took fish home for meals, with larger catches partly sold or preserved as salted fish.
One resident said similar conditions had appeared along the Cha-am coast during the previous week, prompting fishermen to watch for changes in Hua Hin.
How ‘nam biat’ affects fish
“Nam biat” describes different bodies of water meeting and pressing against one another.
The Department of Marine and Coastal Resources, in its explanation of previous incidents, says large freshwater inflows can create layers of water that mix slowly. Oxygen in the lower layer can become depleted, putting marine life under stress.
The phenomenon can also involve discoloured water associated with plankton blooms. As large quantities of plankton die and decompose, oxygen levels can fall rapidly.
These conditions can force fish towards the surface or shallower water. Fish unable to escape may die, providing a possible explanation for fish washing ashore in Hua Hin.
However, the precise cause of the latest discolouration and gathering of fish still requires investigation by the relevant authorities. The water’s appearance alone does not establish which process is responsible.