Introduction to the Current Problem Facing Fisheries

Bycatch

Fishing vessels throw back into the ocean a large percentage of their haul because the fish are not big enough or are not in demand. Federal regulations mandate that bycatch must be returned to the ocean as "unharmed as possible" which is suppose to keep fish from being overexploited but bycatch restrictions often are not implemented or enforced. When they are, most fish thrown back eventually die (Turning A Blind Eye ¶ 1-3).

Though federal law requires it, fisheries' managers sometimes do not monitor bycatch levels. The managers must keep track of the fish and other marine animals killed so that fisheries can be well managed so that healthy fish do not become unhealthy, unhealthy fish are not pushed further towards endangerment and the marine environment is not despoiled. (Turning A Blind Eye ¶ 4).

High mortality rates for non target fish species can change the ecology of an area by changing the food web relationships, altering predator-prey interactions, and destroying the environment. In the long term, bycatch can lead to overfishing, decreased productivity, and reduction in the amount of catch (Turning A Blind Eye ¶ 5).

Almost 1,000 marine mammals, many species of which are critically endangered, die every day due to being tangled in fishing equipment, mainly nets. It is estimated that there are 308,000 accidental marine mammal deaths annually in fishermen's catch (Verrengia ¶ 1). The study indicates that the largest threat facing marine animals is bycatch, more so than pollution and collisions with ships (Verrengia ¶ 4). The researchers do admit that their methods were rather crude since information on marine deaths was not available so they the numbers they reported were found by multiplying numbers from the United States statistical data (Verrengia ¶ 17).

Since the 80's, whaling was banned by the IWC but some like Norway ignore the ban, Japan under a special research loophole takes almost 700 whales a year, and some native groups still hunt on a small basis (Verrengia ¶ 10). Advocates for commercial fishers say that since the US has put in new regulations governing fishing and upgraded technology, deaths of marine animals has decreased by 40 percent (Verrengia ¶ 13). Some improvements such as underwater alarms were implemented with the aid of fishermen during the 1990s (Verrengia ¶ 14). Scientists say that nets wrapped around the bodies of these mammals are often quickly cut away by fishermen so that they will not be traced by their equipment (Verrengia ¶ 15).

The FAO estimated in 1994 that an average of 27 million metric tonnes (between 19.9 and 39.5) or 30% of the global catch was made of discarded fish. In 1998 the FAO reduced this number to about 20 million tonnes and then revised it again in 2005 to about 7.3 million tonnes or 8% of global catch, a drastic reduction from previous estimations (ICES Report 2005 pg. 9).

Introduction to Different Fishing Gear and Their Impacts

Precatching Technology

Precatching technology is a technology that prepares an area for catching fish. The purpose of having this technology is to reduce the amount of bycatch. The ideal technology would separate the fish not only based on size but on type as well. This can be done in several ways.

The technology can use a fish's basic instinctual defense mechanisms to separate fish type. Because fish respond differently when faced with danger, some fish will exhibit a behavior that others may not. Some fish may dive while others may rise. Some may stop moving while some may move in the opposite direction.

The technology can also use electric fields generated in water to separate fish. This is based on the fact that fish respond to electric fields. Currently, this is being used in research and fishing in a form of fishing called electrofishing. Electrofishing means using electric fields generated by two electrodes placed in the water to attract fish. It can use both AC or DC waves which causes different behavior in the fish. When generating an electric field using DC, fish will swim to the positive electrode placed in the water. When using AC, based on the wavelength of the wave, different sized fish will be attracted. Fish smaller than the wavelength will not be attracted while fish larger than the wavelength will be attracted to the electric field zone between the two electrodes. Also, by changing the size and shape of the electrodes, the field changes allows for a larger area or a more specific area.

Another idea that our technology can use is underwater cameras or underwater three-dimensional imaging in real time using an AM laser. By doing this, fishermen can be more selective in where they fish and what they fish.

We hope to achieve precatching technology that can separate fish based on size and type using one or a combination of these ideas.

Mobile Gear

Midwater Trawling

Bottom Trawling

Trawling is usually done by one or two fishing boats vessels with a large net that is dragged for a few hours at a speed of three or four knots in order to catch a range of species that includes orange roughy, hoki, ling, hake, and squid. Trawling is not an option for recreational fishers (Starfish ¶ 8-9).Dredging is usually used to collect scallops, oysters, and clams with a fishing vessel pulling a rigid metal framed dredge along the ocean floor. The bottom of the frame has a raking bar that, depending on the desired species, may or may not have teeth. The haul is pulled up by these teeth and put into a holding container. Dredges are typically used on each side of a ship at the same time (Fishing Methods ¶ 7).Beam trawls drag along the sea floor in front of nets that in mud and sand conditions use tickler chains or in rockier conditions, heavy chain mats. The chains cause fish along the bottom to rise up into the path of the trawl by disturbing them. Depending on the type of ship, the trawls can have beams measuring from 4 to 12 meters that can weigh up seven and a half tons in air (Fishing Methods ¶ 1).Demersal Otter Trawls are also dragged along the sea floor to where boards on the net guide fish into the cone shaped net where they swim. Once exhausted, the fish move backward in the net through the funnel into the cod-end, the fish keeping receptacle of the net (Fishing Methods ¶ 2).The new generation of equipment geared for trawling is doing great damage to the sea floor and changing the habitat of the marine animals and plants. The equipment can be used on every kind of bottom composition. For areas that have rough terrain, "rockhopper" equipment is used as of the 80s which consists of weighty wheels attached to a net that rolls over the sea floor. This equipment means that fishermen who used methods that were environmentally friendly like hook and line and trapping are replaced by this new equipment (Safina ¶ 4).Bottom trawls affect up to several inches into the seabed, disrupting the bottom habitat and the animals that live there including unique structures made by living creatures. Trawls kill marine life, destroying food sources and shelter which endangers the young fish and decreases the ability of the fish to create new generations (Safina ¶ 5).Trawling most affects the top part of the sediment were most animals of interest to humans live. Rockhopper gear at a study site in the GulfofMaine destroyed much of the surface of the sea floor and the life forms on the surface. Rocks and stones were also disturbed. (Safina ¶ 6).The degradation of habitat caused by trawling makes fish of commercial interest more in danger to natural predators. Lab studies of the relationship between sea floor composition and predation showed that more complex habitats like rocks rather than simple habitats like sand or mud gave prey fish like young cod more time to escape their predators. George's Bank is trawled 3 or 4 times a year, regions of the North Sea as many as 7 times, and Queensland of Australia as much as 8 times a year. Each trawl pass kills between 5 and 20 percent of the marine life on the sea floor so that even a single year's trawling can wholly take out the bottom life (Safina ¶ 7-8).Though the populations of fish and commercial fishing are very important, they are difficult to study because there are few sites that can be used as controls. The studies that have been done that the augmentation in benthic trawling from the 1960s to more than 30 years later have likely reduced the capability of the sea floor to reproduce which is further intensified by over fishing of fish stocks (Safina ¶ 9)."At three New England sites, which scientists have studied either within and adjacent to areas closed to bottom trawls or before and after initial impact, trawls significantly reduced cover for juvenile fishes and the bottom community. In northwestern Australia, the proportion of high-value snappers, emperors, and groupers-species that congregate around sponge and soft-coral communities-dropped from about 60 percent of the catch before trawling to 15 percent thereafter, whereas less valuable fish associated with sand bottoms became more abundant" (Safina ¶ 10).Studies done near the Nova Scotia area show that young cod are more able to survive in complex habitats which can give them more protection for predation. A second study showed that shrimp population was much higher outside drag paths than in them (Safina ¶ 12).Trawling is not actually counter beneficial to all marine life and bottom compositions since some of them are more productive in areas that are trawled than in the original habitat. Dab is an example of these marine animals because trawling removes its source of predation and competition while also providing them with nourishment. Generally though most species are not aided by clear cut habitats and these habitats can be seriously hurt and may not recover for many tens of years (Safina ¶ 16).Bottom habitats that are near to the surface often experience storms or other events which make them able to recover quickly when physical trauma occurs. Habitats much deeper do not recover as quickly from destructive fishing methods because they are rarely disturbed and thus not as able to recover. Watling and Norse's study reviews found that none of the different habitats and depths gained general fish species after trawling occurred there but one region did show increase in species while the other decreased. Four of the areas included in the review showed no notables changes though 18 others indicated considerable damage. The majority of the studies were done in habitats close to the surface which are more able to recover which probably affected the findings of the review. "Watling has said that if trawling stopped today, some areas could recover substantially within months, but certain bottom communities may need as much as a century" (Safina ¶ 17-18)."The Grand Banks study showed trawls making furrows but also smoothing out the sandy bottom, and lowering the abundance of sea urchins, snow crabs, soft corals, and other "epibenthic" creatures atop the seabed. As in Minas Basis, effects were less than expected, and were overshadowed by natural variability. Recovery took place within a year, and no long-term impacts were observed. The researchers moved on to Western Bank off Nova Scotia, with a gravelly seabed typical of trawling areas. The 1997-1999 study in this area also monitored trawling's effects on the food supply of fish. It turned out that it made some food organisms, such as horse mussels and worms, more available as prey items. Physical disruptions were less than on sandy bottom, but lasted longer, because gravel bottom undergoes less disturbance from storms...On fishing banks, relatively shallow plateaus in the ocean, strong winds can swirl the water right down to the bottom. Gales and storms will often remould sandy bottom, but gravel is harder to move" (Does fish-trawling harm the seabed? ¶ 10-12).In all the studied area, trawling did less destruction than was anticipated. However, damage increased as the size of the marine life grows in size, especially the marine life that grows vertically which made sponges and corals very exposed (Does fish-trawling harm the seabed? ¶ 15).Studies have indicated that the destruction depends on the type of sediment and organisms on the sea floor, fishing input, and other aspects. Sandy sediment is able to bounce back whereas more rigid bottoms encrusted with life are less able to recover. Trawling is this acceptable in some regions but not in other. "Don Gordon hopes for a future, fine-scale seabed inventory for the seabed off Atlantic Canada. Detailed seabed maps are essential, he believes, to manage human activities in a scientifically sound manner and minimize environmental" (Does fish-trawling harm the seabed? ¶ 17-18).Sediment ResuspensionThe clouds of sediment caused by the dragging trawl doors of trawling nets help bring fish into the nets. The sediment load is also increased by the sediment disturbed by the trawls and can diminish light levels reaching the bottom as well as stifling the bottom inhabitants when the cloud returns to the bottom. "Galtsoff (1964) showed that as little as 1mm of silt over a settlement could prevent spat settlement in Ostrea virginica and Stevens (1987) claimed that high turbidity levels inhibited settlement of Pecten novaezelandiae veliger larvae, depresses growth rates of adults, and caused inefficient metabolism of glycogen stores through enforced anaerobic respiration" (J. B. Jones p. 61). Trawl gear can also bring about vertical redistribution of sediment layers...Mayer et al. (1991) showed that heavy chain dredges could mix organic material into subsurface layers. This organic material removed from the surface metazoan-microbial aerobic chain to an anaerobic system. If the subsurface layers are already anoxic, further problems can occur. Churning up the soft bottom can create anaerobic turbid conditions which are, for example, capable of killing scallop larvae...Anderson & Meyer (1986) who found that sediment resuspended from clam dredges in a Maine estuary did not improve the food value of the suspended materials available to filter feeders... actually decreased the food value since filter feeders had to filter more material to obtain nutrients" (J. B. Jones p. 62).Destruction of Non-target Benthos"The large, heavy-shelled bivalve Cyprina islandica formed a substantial part of the food of cod and flatfish in KielBay (Baltic) only after trawling began in the area. Arntz & Weber (1970) concluded that the fish were feeding on bivalves crushed by the otter boards. Medcof & Caddy (1971) and Caddy (1973) confirmed there was feeding on exposed and damaged benthic animals in trawl tracks. By contrast, observations made using submersibles, reported in Stevens (1990), found that trawling caused no observable injuries to crabs whereas Butcher et al. (1981) found little or no damage to the Jervis Bay (Australia) environment by scallop dredging...Bull (1986) found that survival Pecten novaezelandiae spat in Golden Bay (New Zealand) was better than 20% after 9 months in an area closed to trawling but was only 0.8% for an adjacent site which was open to trawling" (J. B. Jones p. 62).Indirect Effects"McLoughlin et al. (1991) review studies of natural mortality on scallop beds which showed that natural mortality and indirect fishing mortality rates were much higher on fished scallop beds than the natural mortality on unfished beds. They point out that postfishing mortality is not just confined to shells damaged by dredges. Their study showed that 4-5 times as many scallops were crushed or damaged as were caught and landed by the scallop gear used in the Bass Strait (*Australia) fishery. However, within 9 months of the start of the fishery "virtually the entire stock was lost", which McLoughlin et al. (1991) attributed to a suspected bacterial infection resulting from decomposing scallops on the seabed...Saxton (1980) noted a decline in juvenile fish with the removal of bryozoan beds in Tasman Bay, New Zealand. Sainsbury (1988) found a significant reduction in sponge frequency on the Australian north-west shelf between 1967-73 and 1979. Loss of sponges, together with alcyonarians and gorgonians, lead to a change in the catch composition of the pair-trawl fishery on the Australian north-west shelf between those years. The fishes* Lethrinus and Lutjanus were associated with habitats containing large epibenthos and catches of these fish species had significantly declined. The fishes Nemipterus and Saurida occurred mostly over the open sand and had increased in biomass" (J. B. Jones p. 63).ConclusionThe elimination of life on the sea floor has differing effects. In areas close to the surface if the harm is limited and ample recovery time is allowed then the area can recover, but areas where the bottom is considerably damaged and little time is allowed for recovery, then the changes are permanent. Examples include the Sabellaria beds of the Wadden Sea as well as the TasmanBay's bryozoan beds (J. B. Jones p. 64).

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 (Australian Fisheries Management Authority, 2005, diagram 1).  The Marine Conservation Society summarizes purse seining as, "one of the most aggressive methods of fishing and aims to capture large, dense shoals of mobile fish . . ." (Marine Conservation Society, 2000, ¶1).  This method is extremely effective for catching both surface dwelling and mid-water fish, especially tuna, sardines, mackerel, jack mackerel, and herring (Kuznetsov, 2006, ¶4).  Historically, the purse seine was also used extensively for harvesting barracuda, yellowtail, and white sea bass (Skogsberg, 1925, article V.I).  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.  This yield consists of mainly pink salmon, but it also includes sockeye, coho, chum, and chinook salmon.  This Current regulations in Alaska allow purse seining only in specific districts (Alaska Department of Fish and Game, 2005, ¶1,4).

New Technologies

    While fishing companies have practiced purse seining  essentially unchanged for the past 100 years, slight innovations in technology have recently made the net even more efficient and, therefore, lucrative.  One such example is the "autonomous distance-controlled hydroacoustic system" which, once attached to strategic points along the net and submersed, emanates a low-frequency pulse which frightens fish into the net.  This invention consists of a management block onboard the ship as well as the underwater blocks, attached to the net, which emanate the frequencies (Kuznetsov, 2006, ¶4).

     One invention analogous to the hydroacoustic system, but used for trawling, is the "towed remote controlled pneumoacoustic system."  This machine, which is dragged between ship and trawl, creates a strategically located acoustic field, imitating the acoustics generated by predatory whales.  Seeking to avoid the predator, fish congregate in the trawl's catching zone.  This method greatly increases the catch without the necessity of altering boats or nets (Kuznetsov, 2006, ¶1).

Pros

     From the fisherman's point of view, the most obvious advantage of purse seining is its capability to harvest massive quantities of a species at once.  With respect to the geographical environment (i.e. ocean floor, plant life), the purse seine is nearly harmless because, when properly handled, it never touches the sea floor. It doesn't sit in one place for a length of time longer than the boat can set it out and pull it in, thereby hardly altering the long term habitat with its temporary presence.  Yet another defense for purse seining is its longevity.  Purse seining has been practiced to the same end, and with virtually the same means, for the past one hundred years.  Its practice preserves a culture more than one hundred years old of seine net fishing, especially prominent in California and the Northeastern coast of the United States (Skogsberg, 1925, footnotes 7,12).

Cons

    Two general problems with purse seining are caused by its large-scale capabilities.  The first is simply ecosystem disruption.  The instantaneous removal of entire schools of a certain species of fish  from an area leaves a vacant hole in the food web.  This leads, initially, to predator death by starvation and prey overpopulation because their numbers are suddenly unchecked by a predator.  In the long run, if the affected species survive, they may adapt their eating/breeding habits to flourish in a new and altered ecosystem.

    The second flaw of purse seining is the large quantities of bycatch routinely caught and killed along with market fish.  Marine mammals are commonly trapped within the encircling net, and they perish without means to escape.  Before regulations forbade it, seining for yellowfin tuna often consisted of setting nets around dolphins (predators of tuna) on purpose to catch the most fish.  Congress's Marine Mammals Protection Act of 1972, however, almost entirely eliminated the practice by 1997 (Marine Conservation Society, 2000, ¶2).  Additional regulations were set up by the Earth Island Institute and the HJ Heinz corporation in their 1990 "Dolphin Safe" standards (presented in International Marine Mammal Project, 2003, ¶2).  Since their introduction in 1990, these guidelines have been accepted by 90% of world canned tuna companies and have reduced dolphin mortality (as bycatch) by 98% (now about 2-3,00 dolphin deaths per year) (Marine Conservation Society, 2000, ¶2).

Reducing Bycatch: The Dolphin Safe Standard

     The Earth Island Institute writes:

"In order for tuna to be considered "Dolphin Safe", it must meet the following standards:

1. No intentional chasing, netting or encirclement of dolphins during an entire tuna fishing trip;
2. No use of drift gill nets to catch tuna;
3. No accidental killing or serious injury to any dolphins during net sets;
4. No mixing of dolphin-safe and dolphin-deadly tuna in individual boat wells (for accidental kill of dolphins), or in processing or storage facilities; and
5. Each trip in the Eastern Tropical Pacific Ocean (ETP) by vessels 400 gross tons and above must have an independent observer on board attesting to the compliance with points (1) through (4) above."                       (International Marine Mammal Project, 2003, ¶2)

As stated before, since the Earth Island Institute introduced them in 1990,  these guidelines have been accepted by 90% of world canned tuna companies and have reduced dolphin mortality (as bycatch) by 98% (now about 2-3,00 dolphin deaths per year) (MCS).  Fifty-one world nations, including the United States, Canada, Japan, and the United Kingdom, are currently monitored for Dolphin Safe in their tuna industry by the International Marine Mammal Project, a division of the Earth Island Institute (International Marine Mammal Project, 2003, table 1).

Summary

To conclude the past sections, the world's three most lucrative fishing methods (and likewise the ones that remove most of the ocean's fish) are:

1. Bottom trawling
2. Mid-water trawling
3. Purse Seining            (Gabriel, 2005, chap. 26)

Bibliography: Purse Seining

Alaska Department of Fish and Game: Division of Commercial Fisheries. (2005, July 26). Commercial Purse Seine Fishery. Retrieved  November 8,  2007, from                                                     http://www.cf.adfg.state.ak.us/region1/finfish/salmon/netfisheries/ps_info.php

Australian Fisheries Management Authority, Australian Government. (2005). "Seine."  Retrieved November 8, 2007, from http://www.afma.gov.au/information/students/methods/

Gabriel, O., ed. (2005). Fish catching methods of the world. Oxford, UK; Ames, IA: Blackwell Publishing.

International Marine Mammal Project, Earth Island Institute. (2003)  International Dolphin Safe Monitoring Program. Retrieved November 8, 2007, from                                                                http://www.earthisland.org/dolphinSafeTuna/  

Kuznetsov, Dr. J.A. (2006, June 21). Innovational Projects.  Intensification of Multispecies Fishery. Retrieved November 8, 2007, from imf.fish-net.ru/inpr.htm

Marine Conservation Society. (2000). Purse seining.  Fish Online: Fishing Methods. Retrieved October 17, 2007, from http://www.fishonline.org/caught_at_sea/methods/

Skogsberg, Tage. (1925). Preliminary Investigation of the Purse Seine Industry of Southern California, Fish Bulletin No. 9.  State of California Fish and Game Commission, State                          Fisheries Laboratory. Sacramento: California State Printing.

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.

In 1995, the FAO deemed ghost fishing to be one of the most seriously negative impacts in the present capture fishery industry (Matsuoka). When traps are lost, from storms or human negligence or otherwise, the vast majority will continue to catch and trap fish or other ocean life for months, or even years. Ghost fishing in some commercial stocks is estimated to be equal to 5-30% of the annual catch levels (Laist). There are already some measures being taken to prevent ghost fishing: the FAO code of conduct states that States should try to minimize catch by lost or abandoned gear, and many countries including Sweden, Poland, New Zealand, and the United States all have gear retrieval programs (Brown).

Gear retrieval programs, however, are not the best way to prevent ghost fishing. A study by Brown and Macfayden indicates that while these programs save fishermen about $32,000 per fleet per year, the time and money spent in retrieving the gear exceeds $65,000. But if these programs are used along with measures that prevent gear loss in the first place, the cost will decrease significantly. Another possibility is to develop new technology that allows for easier and cheaper retrieval of lost nets and traps.

Another measure being taken is the requirement of escape mechanisms. <<INFO>>. If these requirements are made more strict and widespread, then ghost fishing should decrease dramatically.

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

"Electrified ticklers, which are less damaging to the seabed, have been developed but used only experimentally. Work is also being carried out to investigate whether square mesh panels (see below) fitted in the 'belly' or lower panel of the net can reduce the impact of beam trawling on communities living on or in the seabed" (Fishonline ¶ 1)."The selectivity of trawl fisheries may be increased by the use of devices known as separator trawls. Separator trawls exploit behavioural differences between fish species and can be used, for example, to segregate cod and plaice into the lower compartment of the net, whilst haddock are taken in the upper part. The mesh size for the two compartments can be altered according to the size of the adult fish being targeted. Insertion of square mesh panels also improves selectivity of the net because square meshes, unlike the traditional diamond shape meshes, do not close when the net is towed. Discarding of immature fish may also be reduced by increasing the basic mesh size in fishing nets. Sorting grids are compulsorily fitted in nets in some prawn and shrimp fisheries to reduce bycatch of unwanted or non-target species, including small prawns and shrimp" (Fishonline ¶ 3)."Most fishing methods target fish for direct human consumption. Fisheries targeting species for reduction purposes i.e. the manufacture of fish oil and meal, are referred to as industrial fisheries. Fish meal and oil is produced almost exclusively from small, pelagic species, for which there is little or no demand for direct human consumption. The methods of capture are purse-seining and trawling with small mesh nets in the range of 16-32 mm. Important industrial fisheries in South America include the Chilean jack mackerel fishery and the Peruvian fishery for anchoveta. Industrial species in the North Sea and North-East Atlantic include: sandeel, sprat, capelin, blue whiting, Norway pout and horse mackerel. Fish oil is used in a range of products including margarine and biscuits. Fish meal and oil has more widespread use, however, in the manufacture of pelleted feedstuffs for intensively farmed poultry, pigs and, not least, aquaculture. One of the main impacts associated with industrial fishing is the removal of large quantities of species from the base of the food chain" (Fishonline ¶ 28-29).

Policy and Regulation Relating to Fishing Technology

"Actions that would simultaneously safeguard the fishing industry as well as the seabed need to be taken now. These measures would include: 1) No-take replenishment zones where fishing is prohibited. This would help create healthy habitats supplying adjacent areas with catchable fish. Such designations are increasingly common around the world, particularly in certain areas of the tropics, and benefits often appear within a few years. In New England, fish populations are still very low, but they are increasing in areas that the regional fishery management councils and National Marine Fisheries Service have temporarily closed to fishing after the collapse of cod and other important fish populations. The agencies should make some of these closings permanent to permit the areas' replenishment and allow research on their recovery rates. 2) 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 doesn't destroy habitat. New Zealand and Australia have closed areas to bottom trawls. So have some U.S. states, although these closures are usually attempts to protect fish in especially vulnerable areas or to reduce conflicts between trawls and other fishers, not to protect habitat. Temporary closures in federal waters, such as those in New England, should in some cases be made permanent for trawls but opened to relatively benign stationary gear. What gear is permitted should depend on bottom type, with mobile gear allowed more on shallow sandy bottoms that are relatively resistant to disturbance but barred from harder, higher-relief, and deeper bottoms where trawler damage is much more serious. 3) Incentives for development of fishing gear that does not degrade the very habitat on which the fishing communities ultimately depend. Fish and fisheries have been hurt by perverse subsidies that have encouraged overfishing, overcapacity of fishing boats, and degradation of habitat and marine ecosystems. Intelligently designed financial incentives for encouraging new and more benign technology could tap the inherent inventiveness of fishers in constructive ways" (Safina ¶ 19-22).

Citations

Does fish-trawling harm the seabed?-Finding out the facts (n.d.). Retrieved September 27, 2007, from http://www.dfo-mpo.gc.ca/science/Story/maritimes/trawling_e.htm

Fishing methods (n.d.). Retrieved September 13, 2007, from http://www.fishonline.org/site/www/caught_at_sea/methods

Fishing Methods (n.d.). Retrieved September 13, 2007, from http://www.starfish.govt.nz/science/facts/fact-methods.htmJones,

Jones, J. B. (1992). Environmental impact of trawling on the seabed: a review [12DOT000S2FA07:Electronic version]. New Zealand Journal of Marine and Freshwater Research, 26, 59 -67.

Safina, C. (n.d.). Scorched-Earth Fishing. Retrieved September 27, 2007, from http://issues.org/14.3/safina.htm

Turning a blind eye: A marine fish conservation network report (2006, June 1). Retrieved September 27, 2007, from http://www.uspirg.org/home/reports/report-archives/ocean-conservation/ocean-conservation/turning-a-blind-eye-a-marine-fish-conservation-network-reportVerrengia(2003, June 15).

Nearly 1,000 whales drowning in fishing nets: study. Retrieved September 13, 2007, from http://www.eurocbc.org/bycatch_death_toll_may_exceed_1000_cetaceans_daily_15june2003page1156.html 

World Fish Production

Sources (in progress)

General Knowledge / Article Search Engine

• Wikipedia - http://en.wikipedia.org/wiki/Fishing#Fishing_techniques
• Encyclopedia Britannica - http://search.eb.com/
• Web of Knowledge - http://portal.isiknowledge.com/portal.cgi/wos?Init=Yes&SID=2AN2mMFka9JegBPfAKb

Articles

• World Fish Production - http://www.earth-policy.org/Indicators/Fish/Fish_data.htm#fig1
• Marine Fishery Production - http://search.eb.com/eb/article-230490