Long-line fishing

From Wikipedia, the free encyclopedia

Or see long line (topology) and long line (telecommunications).

Long-line fishing is a commercial fishing technique that uses hundreds or even thousands of baited hooks hanging from a single line. Swordfish, tuna, halibut, sablefish and Patagonian toothfish are commonly caught by this method. In some unstable fisheries such as that of Patagonian toothfish in New Zealand, fishermen may be limited to as few as 25 hooks on a line. In contrast, American long-liners in certain robust fisheries of the Bering Sea and North Pacific generally run over 2500 hand-baited hooks on a single line. Long-lines can be set to hang near the surface to catch pelagic fish such as tuna, or along the sea floor for groundfish such as halibut or cod. Fishermen working in the North Pacific will commonly set gear for sablefish at depths of up to 600 fathoms (1100 meters).

Long-line fishing is controversial in some areas because the lines can lead to by-catch, in endangered species such as sea turtles, petrels and albatrosses this can sometimes have a significant effect on populations. Methods to mitigate such incidental mortality have been developed and successfully implemented in some fisheries. These include the use of weights to ensure the lines sink quickly, the deployment of streamer lines to scare birds away from the baited hooks as they are deployed, setting lines only at night with ship lighting kept low (to avoid attracting birds), limiting fishing seasons to the southern winter (when most seabirds are not feeding young), and not discharging offal while setting lines. However, gear modifications do not eliminate by-catch of endangered species and remain somewhat controversial. In March 2006, the Hawaii long-line swordfish fishing season was closed due to excessive loggerhead sea turtle by-catch after being open only a few months despite using modified circle hooks, which attempt to reduce by-catch.

These issues aside, long-lining is one of the most efficient methods of commercial fishing. The impact on marine habitats in long-lining is far less than that of seafloor trawling or dredging. In many fisheries, it is not uncommon for a trawler to dump 40% of its now lifeless catch back into the ocean, this being extremely destructive because it destroys growing generations of sea life. With long-line gear, juvenile or unwanted fish can be identified and returned to the sea, very often unharmed depending on the species. However, due to the length of time fish remain on the hook, many are inadvertently killed. As a result of overfishing, the Atlantic Swordfish caught by long-line are now predominantly young fish under 100 lbs (45 kg), with the number of large breeding fish having been reduced dramatically. Strict regulation and scientific observation are the most important steps towards ecological sustainability no matter what the fishing method.