Trawling
Trawling is a method of fishing that works by pulling a large fishing net through the water behind one or more boats. In order to hold the mouth of the net open while towing, a system of wires connected to the net and a sufficient towing speed is needed. The net and gear connect to the source of towing power which is required to cast and haul the trawl.
Trawling may be an effective technique, but may also be destructive, since it sweeps up both desirable and undesirable fish (by-catch) and scrapes up the seabed. Bottom trawling is a trawling technique where the net is dragged along the seafloor. Some argue that this fishing technique destroys the habitats of many important organisms living on the bottom. Bottom trawling however requires a flat and sandy or muddy sea floor, which excludes large areas. Pelagic trawling is considered by many to be much more destructive, nabbing large numbers of juveniles.
Although trawling today is heavily regulated, it remains the target of many protests by environmentalists.
The word "trawling" has come to be used in a number of non-fishing contexts, generally referred to indiscriminate collection with the intent of picking out the interesting bits. For instance, in law enforcement it may refer to the practice of collecting large records of phone calls in the hopes of finding calls made by suspects. The word "trawling" occurs frequently in general literature and is used to mean searching through literature as often as it is used to mean catching fish.
In some older books, for example "Captains Courageous" by Rudyard Kipling, the word "trawl" is used to mean the fishing method which is now called "long-lining". This sense is now obsolete.