Backround Information
This type of boat uses lines and hooks to catch fish rather than a net. Why, then, is it called a trawler if it does not use nets, or trawls? These boats automatically bait, release, and reel in line in order to obtain wild fish. This method could actually avoid some of the by-catch because of the difference in diet of some fish living in the same area. The boats operate 24 hours a day, six days a week tending to the thousands of hooks sent out each day.

Longline fishing envolves releasing thousands of hooks at one single water column. A water column is a specific level of water. This method can't be used to catch bivalves, crustacians, or mollusks. Using this method envolves lower fuel consumption and a more precise selectivity of fish. Some species targeted by the longlines include:
  • swordfish
  • tuna
  • halibut
  • sablefish

Environmental Problems
Although this fishing technique was employed to avoid by-catch, it still occurs. Sea birds will try to feed on a prey species which has been hooked, thereby hooking themselves. Dolphins, which swim and hunt with the target species of yellow tuna, also get hooked. It actually closed the longline fishing season because of an excess by-catch of loggerhead sea turtle in March of 2006. To avoid all of this, the fishing season was limited to winter, when the animals aren't feeding their young or have migrated out of the area. Unstable fisheries can be limited to as little as 25 hooks per line.