Thai Fishermen

On our way from the Hermod to Songkhla vice versa, it was impossible to follow a straight line in the chart. This was because an immense number of Thai fishingvessels, trying to catch their daily bread. Thailand has a huge fleet of thousands of these vessels.
Fish stocks in Thai waters have dropped to less than 2 million tonnes in 2011, from an average of 2.4 million to 2.7 million over the previous decade.

I don't know what kind of fish they land, but they are using awful bright decklights for it to catch them, the whole horizon is lit when you approach another fleet of them.