Introduction to the Current Problem Facing Fisheries
Bycatch
Fishing vessels discard a large portion of their catch, often dead or dying. They are thrown overboard because they are too small, or have little or no economic value. Most discards are mandatory by federal regulations that require that bycatch be returned to the ocean as unharmed as possible. The measure is intended to prevent wanton overexploitation but bycatch restrictions often not implemented or enforced and even if they are, most fish returned to ocean do not survive. (Turning A Blind Eye)
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Nearly 1,000 whales, dolphins, and porpoises drown every day after being tangled in fishing nets and other equipment. Annually, it is estimated that 308,000 marine mammals die unintentionally in fisherman's haul. The study indicates that accidental captures ("bycatch") may be the biggest immediate threat, more than ship collisions and pollution. The IWC banned most whaling in the 1980s but Norway ignores this ban and Japan takes nearly 700 whales a year under a controversial IWC research exemption. Some native cultures are allowed to conduct strictly limited hunts. Commercial fishing advocates point out that cetacean deaths decreased 40 percent in the US in the last decade as new federal laws were enacted and equipment improved. Some measures such as underwater alarms were employed in late 1990s with the help of fishermen. Scientists say some fishermen rush to cut away line and nets wrapped around bodies of dead whales before they can be traced through their equipment. The researchers acknowledge that their methods were very crude (found by multiplying U.S. statistics because mortality figures in remote countries were not available) (Verrengia)
Introduction to Different Fishing Gear and Their Impacts
Precatching Technology
Mobile Gear
Midwater Trawling
Bottom Trawling
Trawling involves one or two fishing vessels towing a large net usually for two or three hours at three or four knots and is used to catch a range of species including orange roughy, hoki, ling, hake, and squid. Recreational fishers are not permitted to use trawl nets. (Starfish)
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The removal of macrobenthos has variable effects. In shallow waters where damage is intermittent, recolonisation occurs quickly. Where macrobenthos is substantially removed and recovery is not permitted, the change is permanent (Ex - Sabellaria beds of Wadden Sea and the bryozoan beds of Tasman Bay) (J. B. Jones)
Nonmobile Gear
Purse Seining
The purse seine is a vertically hanging net with floats on its surface line and lead weights on its bottom edge. Attached to the weighted line are rings strung together by a drawstring wire. Ships encircle entire schools with the outstretched purse seine, then they pull the drawstring wire tight to trap the fish inside (AFMA). This method is extremely effective for catching both surface dwelling and mid-water fish, especially tuna, sardines, mackerel, jack mackerel, and herring (Kuznetsov). The Alaska Department of Fish and Game reports that, in the commercial fisheries of Southeast Alaska, purse seines are responsible for 70-90% of the tuna catch alone. Current regulations in Alaska allow purse seining only in specific districts (ADFG).
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Alaska Department of Fish and Game: Division of Commercial Fisheries. "Commercial Purse Seine Fishery." 26 July 2005. 17 Oct. 2007 <http://www.cf.adfg.state.ak.us/region1/finfish/salmon/netfisheries/ps_info.php
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Australian Fisheries Management Authority, Australian Government. "Seine." Canberra, Australia. 29 June 2005 <http://www.afma.gov.au/information/students/methods/>.
Kuznetsov, Dr. J.A. "Innovational Projects." Intensification of Multispecies Fishery. Vladivostok, Russia. <imf.fish-net.ru/inpr.htm>.
Traps
Traps are one of the most environmentally friendly fishing methods. They are highly selective, since fishermen can release unwanted fish alive when the traps are hauled up. They also do little to no harm to the ocean floor or other oceanic surroundings, as they are nonmobile. However, there is a huge problem associated with traps - ghost fishing.
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Unfortunately, there is little data about the effectiveness of escape mechanisms, or even truly accurate data regarding the impacts of ghost fishing on fish populations; most of the numbers discussed above are mere approximations. This is another area in which we can improve
Hook and Line
Alternative Fishing Technologies
Future improvements on beam trawls include electrified ticklers, which are less damaging to the seabed which have been developed but used only experimentally. Square Mesh Panels fitted in the 'belly' or lower panel of the net can reduce the impact of beam trawling. (Fishonline)
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Most fishing methods target fish for human consumption. Fisheries targeting species for reduction purposes (manufacture of fish oil, meal, etc.) are referred to as industrial fisheries. Fish meal and oil produced almost exclusively from small, pelagic species for which there is little or no demand for direct human consumption. Methods of capture are purse-seining and trawling with small mesh nets (16-32 mm). Industrial species in North Sea and North-East Atlantic include: sandeel, sprat, capelin, blue whiting, Norway pout, and horse mackerel. Fish oil used in products ranging from margarine to biscuits. Fish meal is used in manufacture of pelleted foodstuff for intensively farmed poultry, pigs, and not least, agriculture. The main Impacts of industrial fishing is the removal of large quantities of species from the base of the food chain. (Fishonline)
Policy and Regulation Relating to Fishing Technology
Recommended actions that would simultaneously safeguard the fishing industry as well as the seabed would include no-take replenishment zones where fishing is prohibited which would create healthy habitats supplying adjacent areas with catchable fish where the benefits can be seen within a few years. In New England, fish populations are still low but are increasing in areas where the regional fishery management and National Marine Fisheries Service have temporarily closed to fishing. Fixed-gear-only zones where trawls and other mobile gear are banned in favor of stationary fishing gear such as traps or hooks and lines that don't destroy habitat. What gear is permitted should depend on the bottom composition. Mobile gear allowed on shallow sandy bottom relatively resistant to disturbance but be barred from harder, higher-relief, and deeper bottoms where trawler damage in much more serious. Incentives for development of fish gear should be put in place that do not degrade the habitat on which it is dependent. Fish and fisheries are hurt by perverse subsidies that encourage overfishing, overcapacity of fishing boats, and degradation of habitat and marine ecosystems. Intelligently designed financial incentives are needed to encourage new and more benign technology. (Safina)
Citations
Verrengia, Joseph. "Nearly 1,000 whales drowning daily in fishing nets: study ." European Cetacean Bycatch Campaign. 15 June 2003. 13 Sep. 2007 <http://www.eurocbc.org/bycatch_death_toll_may_exceed_1000_cetaceans_daily_15june2003page1156.html>. "Fishing Methods." STARFISH Student and teacher Resource Science Fact Sheets. New Zealand Ministry of Fisheries. 13 Sep. 2007 <http://www.starfish.govt.nz/science/facts/fact-methods.htm>. "Fishing Methods." FISHONLINE. Marine Conservation Society. 13 Sep. 2007 <http://www.fishonline.org/site/www/caught_at_sea/methods/>. Jones, J. B. . "Environmental impact of trawling on the seabed: a review." New Zealand Journal of Marine and Freshwater Research 26 (1992): 59-67. 13 Sep. 2007 <http://www.rsnz.org/publish/nzjmfr/1992/4.php>. Safina, Carl. "Scorched-Earth Fishing." Issues Online in Science and Technology (1998): 22 pars. 27 Sep. 2007 <http://issues.org/14.3/safina.htm>. "Turning A Blind Eye: A Marine Fish Conservation Network Report." 1 June 2006. U.S. Public Interest Research Groups . 27 Sep. 2007 <http://www.uspirg.org/home/reports/report-archives/ocean-conservation/ocean-conservation/turning-a-blind-eye-a-marine-fish-conservation-network-report>. "Does fish-trawling harm the seabed? - finding out the facts." Fisheries and Oceans Canada Science. Department of Fisheries and Oceans Canada. 27 Sep. 2007 <http://www.dfo-mpo.gc.ca/science/Story/maritimes/trawling_e.htm>.