Another kind of trawling is midwater trawling (also known as pelagic trawling). This is where a net is towed higher in the water column. Midwater trawling catches pelagic fish such as anchovies, tuna, and mackerel. Bottom trawling catches both bottom-living fish. It also catches semi-pelagic species such as cod, squid, shrimp, and rockfish. Trawling is done by a trawler. This can be a small open boat or a large factory trawler.