Industrial ships are designed to carry out industrial processes at sea, like drawing out raw materials and food resources from waters. The activities that take place aboard these ships include extracting oil and mineral salts, or catching and processing fish and crustaceans like crabs, shrimps and lobsters. Thus, if we consider the function the ships perform, we can clearly distinguish between the extractive and processing ships. The first type includes trawlers and seiners. A trawler is the most popular vessel among fishing ships. Its name comes from the name of activity, "trawling", which means catching fish by dragging a fishing net along the sea bed. The trawl can be launched either over the ship side or over the stern. Spain and Norway have been taking the lead with respect to the number, size and variety of trawlers built.



Non-trawling vessels can rangefrom simple crafts which deploy a net, to fishing vessels that first lay out nets, even for a distance of a few kilometres, and then wait for the shoal of fish to swim into it. The typical representatives are seiners, tuna clippers and crab boats. A seiner makes use of a special kind of net called a seine net in the following way: the net hangs vertically in water. Its top edge floats and its bottom is weighted and equipped with a rope. When a shoal of fish swims into the net, the rope tightens and closes around it.

Processing ships receive fish or other sea goods from exctractive ships, process them into products, and bring them to ports. They must be fitted with special machines for processing, canning and storing.