Fishing vessel (trawler, seiner, longliner)

Fishing vessels are grouped by gear, and the three main families are trawlers, seiners, and longliners. A trawler tows a cone-shaped net along the bottom or in midwater, hauling it over a stern ramp or side; the catch is sorted on deck or processed and frozen aboard on a factory trawler. A seiner sets a wall of net around a school: a purse seiner draws a cable through rings along the bottom to close the net into a bag, the standard method for tuna and small pelagics. A longliner deploys a main line of baited hooks, kilometers long, for tuna, swordfish, and demersal species. Gear choice sets the deck layout, the winches, and the target fishery.