TEAM 2 PROPOSED SOLUTION:

    Over the past one hundred years, the fishing industry has developed and expanded to serve increasing consumer demand.   Advances in fishing technology enabled this growth by catching greater quantities of fish with lower cost and less labor required.  The three most lucrative fishing methods, bottom trawling, mid-range trawling, and purse seining, effectively removed entire schools of fish in very little time.  Certain methods, especially bottom trawling, killed surrounding plant and animal species by destroying their sea floor habitat (Gabriel, 2005, chap. 26).  Increased bycatch (nontarget species caught by commercial fishermen) also accompanied the large-scale harvesting, eliminating many populations unintentionally caught with market fish (Merriam-Webster, 2006-2007).  In general, our goals in current fishing technology advancement are to decrease harmful effects on the environment while also increasing selectivity in both species and size of fish harvested.  These ends focus on the restoration of fish habitats and the protection of threatened or endangered species.  The means to accomplish these goals must include action from many sides at once.  Governments must implement and enforce regulations to save declining fisheries.  At the same time, manufacturers must introduce sustainable fishing technologies into the global market.  As the new machinery becomes more common, its prices will drop and its acceptance will increase. 

Improvement in Fishing Technology (Short Term)

General Goals

General goals of the plan include decreasing the harmful effects of fishing technology on the environment and increasing the selectivity of fish caught both by species and size, to the purpose of drastically reducing bycatch. Improving technology and fishing equipment is really only a short term solution to global fisheries problems. Long term solutions will come from intelligent regulations and worldwide cooperation to use our resources wisely.

Technology Suggestions

Step 1:
Step 1 would include the use of methods that are more environmentally friendly such as hand lining or trapping rather than bottom trawling because trawls stir up sediment (turbidity is harmful to many fish species as well as bivalves), destroy fish habitat, and destroy plants and animals that live along the bottom whereas hand lining and other more environmentally friendly methods do not contact the bottom and thus do not harm the nonliving environment and are very selective with little bycatch.

Hook and line however does have a problem with bycatch. The hooks are baited but sometimes fish other than the desired catch will eat the bait. Fishermen sometimes kill the fish and throw them back in so they will not continue to eat their bait. As an alternative, we suggest keeping onboard the boat an aerated tank that the bycatch fish can be put into. At the end of the day when the fishermen are done with their catching, they can release the fish safely back into the ocean.

Also, rather than trawling or fishing for a set number of hours and pulling up the nets to see what and how much has been caught, putting sensors on nets that measure tension or width of the net or other factors that can give fishermen an estimation of the amount of fish in the nets before they pull the nets up. That way the quota allowance will not be exceeded resulting in all of the fish over the quota pound limit being thrown back dead into the ocean.

Putting escape vents in commercial nets would allow the escape of large sea mammals that become trapped inside. Step 1 would also require that nets are manufactured with a biodegradable release mechanism which is often as simple as a long slit in the nylon webbing which is then sealed with cotton thread that degrades away. Traps would also have this time release mechanism that would open and allow the fish inside to escape in the event that the trap is not picked up by the fishermen or blown away by a storm. This provision eliminates the self-perpetuating cycle of self-baiting "ghost traps."

Requiring that nets be manufactured with square mesh sections instead of diamond mesh would make net size regulations more effective because square mesh does not close when towed and thus small fish can get through the mesh. Examples of these bycatch reduction devices include nets with radial escape sections or square mesh windows that allow fish to escape shrimp trawls.

Step 2:

Step 2 would include adding sensors along the bottom of trawling nets that keep the net a certain fixed height above the ground to prevent damaging the sea floor. 

Using electrified ticklers to scare fish into the nets rather than the current chains which scrape the sea floor to scare fish into the nets, would mitigate the environmental impact of trawling.

Implementing sonar and other tracking devices to determine size (and from that age if possible) and species before nets are put into the water would limit the amount of bycatch of unwanted species or fish that are too small.

Implementing devices to sort fish before catching based on instinctual defensive responses or other means such as electrofishing which uses certain frequencies which attract and even paralyze if desired fish of a certain size and repel others away in order to lower bycatch.
Since step 2 is much more technologically advanced and likely to be more expensive, these measures would be implemented later when more research has been done and these technologies can be more cheaply and this wide spread manufactured.

Future Steps:

Another rather advanced idea would be to use GPS tags in nets and other fishing gear that would emit a unique signal that can be tracked by an automated server. Ships would also have a unique GPS tag that can be matched together with their equipment and boats that don't pass inspection (use the right equipment in the right areas such as no trawling areas) would be red flagged by the automated system which the eliminate the need for human operators which could be used more efficiently in the enforcement aspect. This can also tracks ships that fish in no take closed areas. Should the equipment malfunction, a marine geek squad can be sent out to make repairs to the electronic tags. In order to track the number of hours a ship's equipment is in the water a speed coach propeller could be put on nets and other mobile equipment which spins as water passes through and could track the speed and number of hours the equipment is pulled. Hours in the water could also be tracked by a resistance meter that can sense when it is in water because the resistance of the water is much less than of air so as the meter dries, the resistance would drop. 

Implementing the Steps:

Countries that sign the international treaty would agree to convert to 50% of their national fleet to Step 1 sustainable fishing technology in 8 years and 80% in 12 years. Fishermen who choose to convert to sustainable fishing technology would receive larger individual transferrable quotas (ITQs) with the goal of making Step 1 sustainable technology comparable to or cheaper than unsustainable fishing technology.

The time frame must be large enough to allow fishermen to replace their equipment whenever is most convenient for them (i.e., when they would naturally need to replace it), but small enough to leave very little time for inaction and encourage countries to be proactive in their conversions. An extension can be added if it is needed on a case by case basis in order to meet the deadline.

ITQ bonuses for Step 2 technology would be implemented before the Step 1 phase is fully complete so fisherman can choose to go straight to Step 2 and skip Step 1, if they can do so. Step 2 would continue past the end of the ITQ bonuses provided for Step 1 conversion. As sustainable fishing increases and unsustainable fishing decreases, ITQ bonuses for all fishermen would begin to level out.

Individual fishermen and small fishing companies would get larger per-net ITQ bonuses than large companies, who would receive a smaller bonus based on a sliding scale. This is because large fishing companies would find it easier and have more capital available to convert to new technology than smaller groups of fishermen. However, due to this same capital, large fishing fleets might in fact be less likely to make the switch, so we propose that they also receive a tax break.

Regulation of Fishing Technology (Long Term)

The most effective means of managing ocean fisheries long-term will be regulations. Ideally, regulations would occur before fish are caught rather than after. For example, regulation should regulate net drag speed and net mesh size rather than enforcing quotas, which only encourage fishermen to throw fish exceeding the weight limit away. Regulation would be most effective if the two are combined.

Bottom trawling should not be allowed in communities deeper than a certain depth because deep ocean habitats recover much more slowly whereas very shallow areas that are used to storms and other factors which affect the bottom habitat show little or no damage in the succeeding months after trawling has taken place. More research is needed in classifying sediment type according to depth or extensive underwater terrain mapping to show sediment composition so that areas that can be bottom trawled can be marked and those that cannot can also be determined. Bottom trawling should be phased out altogether as newer technology is implemented.

Regulation of where mobile gear (trawls and other similar fishing methods) and non-mobile gear (such as lines or traps) can be used and cannot be used in conjunction with the mapping of underwater terrain would also greatly limit the damage to the sea floor. Mobile gear catches greater volumes of fish, but can be much less selective than non-mobile gear. However, mobile gear is much more cost effective since more fish can be caught in less time with less effort.

For mobile gear, we should regulate at what speed nets can be dragged so as to maximize the benefit of the increased mesh size. At high speeds, fish that would normally be able to escape from the netting are trapped by the larger fish that are pressed against the end of the net. Setting a minimum mesh size that nets cannot exceed would also decrease the bycatch though more research is needed as to what size this minimum should be for the various species being fished.

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   A combination of new technologies makes selectivity and habitat conservation possible, but conversion to these new methods will be costly and difficult.  To ease the transition to more expensive equipment, we propose that ITQs be redirected to support sustainable fishing.  Along these economic lines, tax deductions will also encourage environmentally-friendly methods.  The technologies themselves include digital imaging for catch specificity, line tension sensors to indicate net content, and electronic ticklers with depth sensors for trawl nets.  These and other steps will allow fisherman, even in large-scale commercial corporations, to catch fish of proper size and species without damaging the precious ocean environment.  A shift of the magnitude necessary to restore the fisheries will take time and commitment from across the globe.  Honed regulations from supportive governments can encourage sustainable technologies to restore declining fisheries and unify the fishing community worldwide.

Bibliography

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

Merriam-Webster Dictionary. (2006-2007). Bycatch.  Retrieved  November 17, 2007 from http://www.m-w.com/dictionary

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 p. 9).

Certain countries that are a part of ICES (International Council for the Exploration of the Sea), have put into effect a 'no discard' policy where legislation is targeted at haul composition. For example, in a country if the catch composition has more than 15% of the fish below an allowable catch size, then the area is closed until research can show that the composition level has returned to less than 15%. This measure supports the use of methods that will reduce bycatch in order to avoid area closures and use areas that might not otherwise be open to fishing activity because of the high concentrations of fish below target size. This legislation encourages the industry to implement BRD (Bycatch Reduction Devices) (ICES Report 2005 p. 9).

EU fisheries legislates the amount of fish brought up onto vessels which causes discarding to occur frequently because of a disparity between mesh choice and minimum landing sizes (MLS) or bycatch composition rules which is most commonly seen in mixed-species fishing. Scrapping the MLS regulations would perhaps reduce bycatch levels but could in turn promote gear that is less selective if markets are open to buying undersized fish. In the case of discards happening because of quota inequity such as a lack of quotas for a certain type of fish, the elimination of a quota based system that would be substituted instead by a plan founded on exertion would decrease bycatch (ICES Report 2005 p. 10).

Escape Mortality

Fishing gear capable of greater discernment has the ability to decrease fishing pressure on undesired species, undersized fish, and bycatch reduction. This fishing gear can only be successful if it can be shown that fish survive the escape. In the event that the fish who do manage to escape from cod ends on trawls and other gear, end up dying then measures of increasing mesh size and other selective gear are not effective. Cod and haddock typically have high survival rates whereas small pelagic fish like vendace and herring have rather low rates of survival.

Different factors may affect fish survival that include more than just escaping through the net mesh or other selective devices such as interaction with other fish, debris, or the fishing gear used. The fish may not die immediately from these stressors but may die at a later time. Escaped fish are potentially subject to changes in water temperature, pressure, and light. Different species have different abilities to survive the physical factors included in capture and escape. The smallest fish seem to be most exposed since these small fish have poorer swimming capabilities that mean that they cannot escape harm while traversing fishing gear and may also be less suited for making escape attempts. The result is that they may stay inside gear the longest and sustain the most injury as the weakest members in comparison to their larger counterparts. The reasons that fish die are not particularly well known and more research is necessary to understand how to best address these issues (ICES Report 2005 p. 11).

Fish that escape should remain in the gear for as short a period of time as possible and ought not drift into the cod end where the most damage can be sustained. Escape vents and other selection devices should thus be put before the cod end in order to maximize the likelihood of escape and survival of the smallest fish. Voluntary rather than mechanical selection would cause the least damage to fish and the inclusion of netting that is non-abrasive, the exclusion of objects that can harm fish, and improved net and gear design can increase the chances of survival of fish.

Fishery management techniques often increase mesh size or various other controls as a methods of increasing selectivity. If the survival rate of fish is low then the positive effects of integrating more selective technology could be vastly overestimated which could lead to a lack of understanding of the reality of fishery conditions that in turn could result in non-effective methods of fishery management (ICES Report 2005 p. 12).

Bycatch Reduction Devices (BRD):

Decreasing the amount of bycatch through devices is highly beneficial due to the increased efficiency as damage to nets would be minimized, the length of time used to sort fish would decrease, and crew members would be less likely to be hurt by hazardous animals.

BRDs are integrated into gear, particularly shrimp trawls near the end of the net which permit undesired catch to escape. They are split into two categories by method of escape. The first occurs physically by not allowing the bycatch to reach the cod end and instead diverting them to an exit from the gear. The second exploits the behavior of the desired shrimp and undesired bycatch because fish can swim in mobile nets in the path of the tow to an escape vent whereas the shrimp do not swim directionally and float into the end of the net (FAO Equipment Profile BRD).

Radial Escape Sections for prawn nets are made so that fish can swim out of a large circular ring-shaped panel of square mesh. A net funnel focuses the animals into the mid section of the cod end where the fish can swim forward and out the open square mesh while prawn remain in the cod end due to their inability to swim forward (FAO Equipment Profile RES)











The Radial Escape Section (RES)

FAO Equipment Profile Radial Escape Section

Square Mesh Windows on nets let fish swim upward and out of nets through square meshing while the shrimps that are not as agile stay in the net. Square rather than diamond mesh is used as squares do not collapse when put under tension. Multiple mesh sizes can increase escapees while keeping shrimp from leaving. Square mesh is typically made by knotting which after extended use can slip and warp the shape so it must be replaces in a timely fashion. The non-knotted relation is preferred (FAO Equipment Profile SMW).










Square Mesh Window

FAO Equipment Profile Square Mesh Window

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

Midwater, or pelagic, trawling is perhaps the most widely used form of commercial fishing today. As the name suggests, this fishing takes place in the region between the surface and the sea floor - and it targets the schools of fish that swim through the water column, including mackerel, herring, seabass, tuna, and pollack ("Fishing Methods" 5).

Pelagic trawling vessels work either alone or in pairs to pull nets that can exceed a quarter mile in width and a half mile in length. The large mouth of the net tapers into a conic section called the cod end, where fish are collected ("Fishing Methods" 5). To keep the net open as it is being pulled, floats are positioned along the top of the net and weights are positioned along the bottom ("Midwater Trawls" 1). The depth of the net is controlled by the amount of line let out and the speed with which the net is pulled (generally between 3 and 5 knots). Because the fisher cannot see the net while it is underwater, he relies on sonar to determine where the net is in relation to the fish. A net may be pulled for as little as 10 minutes or as long as 8 hours depending on the number of fish caught ("Mid-water Trawling" 1). In all, a trawler pulls a net for 5-6 hours a day, 220 days a year ("Pelagic Trawls").

In large net designs, like those pulled by two ships, floats are not needed along the top of the net. Instead, a piece on either side of the net called the trawl door (alternatively, the otter board) creates enough tension in the line to force the net open. As fish are swept into the net, they are funneled slowly backward until the net constricts and the force of more incoming fish keeps them from escaping ("Mid-water Trawling").
 
Problems with Pelagic Trawling

  The biggest problem with Pelagic trawling is that is simply too efficient. It takes too many fish from the ocean, and in areas of heavy trawler activity the population of targeted species can fall to near zero. The method also poses a serious threat to marine mammals that feed on the same shoals that are targeted by trawlers. Research suggests that pair trawling has the highest level of dolphin bycatch of any fishing method ("Midwater Trawls 2). In addition, because trawlers sweep up everything in their paths, the rate of incidental capture of non-targeted fish is high.

Methods of Bycatch reduction

Because it is inefficient for non-target fish to remain in the net, net designers have incorporated meshing of different sizes in attempt to allow bycatch to escape. As more pressure is being put on fishers to reduce the cetacean deaths, new nets are beginning to incorporate trap doors through which mammals can escape. Sonar scare devices are also being tested with promising results ("Dolphin Deterrence"). 

Future of Midwater Trawling

Although new net designs are attempting to reduced the incidental bycatch of non-targeted fish and marine mammal species, they do not address the problems associated with scooping up entire schools of fish in a single pull. Obviously, from the perspective of fishers and fishing companies, the ability of pelagic trawls to catch so much is what makes them appealing. Unfortunately, this same ability also allows the unrestrained reduction of global fish populations. As a result, the solution to sustainable fishing with a pelagic trawl rests in the hands of legislation.  

 Bottom Trawling

It is agreed that trawling of deep ocean is the most harmful of all fishing methods to life in the deep. A 2006 study which appeared in Nature concluded that five deep water fish have reached perilously endangered species status due to trawling of their habitats. Three of the five species are caught and discarded by trawling fishermen as valueless ("Dragging the Life" p. 3) 

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 Principle Features of Demersal Otter Trawl Gear
Galbraith and Rice 2004
  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 Gulf of Maine 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).

The leveling of the ocean bottom could result in fish deaths that go unrecorded which are caused by a decrease in the resources available such as food or habitat, particularly for important areas such as nursery grounds. Evidence ties the changes in fish communities to the leveling of their habitat though the mortality is not a direct result of trawling but rather a roundabout effect of the direct effect of environmental change (ICES Report 2005 p. 13).

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 Resuspension

The 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).

Conclusion

The 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

   




Purse-seining

Galbraith and Rice 2004

    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

Potting and Creeling (Traps)

Galbraith and Rice 2004

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 non-mobile. 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, 2005). 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, 1996). 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 and Macfadyen, 2007).

Gear retrieval programs, however, are not the best way to prevent ghost fishing. A study by Brown and Macfadyen (2007) 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. Galvanic time releases especially are becoming more common among pot traps. These mechanisms are simple and relatively cheap; they involve only two cathodes and one anode. When the GTR is placed in an electrolytic solution such as seawater, the anode begins to degrade. After a certain period of time, the anode will have completely worn away and the pot trap will be ineffectual (DENYS'S SOURCE). GTRs are simple and inexpensive; if a way was found for them to be implemented in other types of nets and traps, the problem of ghost fishing would be much closer to being solved.

An alternative to GTRs is biodegradable material. Many nets now contain a small portion that is made of biodegradable materials, so that when the net is lost, it becomes ineffective before too much time has passed (FAO Equipment Profile Biodegradable Material). In pot traps, a panel of such material is usually inserted. While this method seems to be fairly effective, it does mean that such gear will only work for a given amount of time, whether or not they are lost. For this reason, developing improved GTRs would be more advantageous than pursuing biodegradable gear.

Unfortunately, there is little data about the effectiveness of escape mechanisms and biodegradable netting, 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 an area where more research is needed; it is difficult to know how much current mechanisms need to be improved if we do not know how they are performing.

Hook and Line

Alternative Fishing Technologies

Electrified ticklers though developed are still in experimental stages but have been found to be less destructive to the sea floor. Experimental work is also being done on square mesh panels inserted into the bottom of nets can make beam trawling less destructive the ground habitats (Fishonline ¶ 1).

Separator trawls can increase the selective capabilities of nets which use the difference in the behavior of different species of fish to separate them into separate compartments of the net. To that end, different size mesh can be used for each compartment depending upon the size of the fish desired. Square mesh can aid the selectivity of the net since it does not close when towed like the diamond mesh used in most nets. The bycatch of fish which are too small can be mitigated by making the size of the net mesh used larger (Fishonline ¶ 3).

Most commercial fishing is aimed at catching fish for human consumption whereas the subset of industrial fishing aims to catch fish for manufacture such as fish meal and oil which is made from small fishes that have no commercial value in terms of human consumption. They are mostly caught with purse seines and trawlers that use fine mesh (16-32 mm). Fish oil is used is many products which include margarine and biscuits and fish meal is used in pelleted food for poultry, pigs, as well as other fish through aquaculture. The main concern of industrial fishing is the elimination of small fish at lower trophic levels. (Fishonline ¶ 28-29).

Policy and Regulation Relating to Fishing Technology

Measures that are necessary now to preserve the fishing business and the sea floor 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

Biodegradable material (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=equipment&xml=biodegradablematerial.xml_ _

Bycatch Reduction Devices (BRD) (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=equipment&xml=brd.xml

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

Dolphin Deterrence. Retrieved November 14, 2007, from http://www.irishscientist.ie/2002/contents.asp?contentxml=02p55.xml&contentxsl=is02pages.xsl. 

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,

Galbraith, R. D., & Rice, A. (2004). An Introduction to Commerical Fishing Gear and Methods Used in Scotland. Retrieved September 13, 2007, from http://www.marlab.ac.uk/FRS.Web/Uploads/Documents/Fishing%20Gear.pdf

Joint Report of the Study Group on Unaccounted Fishing Mortality (SGUFM) and the Workshop on Unaccounted Fishing Mortality (WKUFM) (2005, September 25). Retrieved November 21, 2007, from http://www.ices.dk/reports/FTC/2005/SGUFM05.pdf

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.

Fishery and Aquaculture Country Profile: China (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=countrysector&xml=FI-CP_CN.xml&lang=en

Fishery and Aquaculture Country Profile: Iceland (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=countrysector&xml=FI-CP_IS.xml&lang=en

Fishery and Aquaculture Country Profile: Japan (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=countrysector&xml=FI-CP_JP.xml&lang=en

Fishery and Aquaculture Country Profile: Kenya (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=countrysector&xml=FI-CP_KE.xml&lang=en

Medina panels (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=equipment&xml=medinapanels.xml

Midwater Trawls. Retrieved October 17, 2007, from http://www.eurocbc.org/page124.html.

The Radial Escape Section (RES) (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=equipment&xml=radialescapesection.xml

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

Square Mesh Window (n.d.). Retrieved November 21, 2007, from http://www.fao.org/fi/website/FIRetrieveAction.do?dom=equipment&xml=squaremeshwindow.xml

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
  

Trapping

Brown, J. and Macfadyen, G. (2007). Ghost Fishing in European Waters: Impacts and Management Responses. Marine Policy, 31(4), 488-504.

Laist, D.W. (1996). Marine Debris Entanglement and Ghost Fishing: A Cryptic and Significant type of Bycatch?. Alaska Sea Grant College Program, Fairbanks, AK. p.33-40.

Matsuoka, T., Nakashima, T., & Nagasawa, N. (2005). A Review of Ghost Fishing: Scientific Approaches to Evaluation and Solutions. Fisheries Science, 71(4), 691-702.