Bycatch and Discards

Definitions

Bycatch: That part of the catch that is made up of marine organisms that are not the primary target of the fishing effort. This includes organisms that die as a result of interaction with the fishing gear, even if they do not leave the water (this can include those that die as a result of "ghost fishing": capture by lost or abandoned fishing gear), as well as those organisms that reach the deck of the fishing vessel.

The bycatch that reaches the deck can be divided into those organisms that are retained and sold ("incidental catch") and those that are discarded or released. The incidental catch, together with the target catch, comprises the "retained catch" or "landed catch" (i.e. that which is brought ashore).

Bycatch can comprise individual species or assemblages of species, and may include undersized (i.e. juveniles) or otherwise unwanted individuals of the target species, and juveniles and adults of non-target species, as well as corals, other seabed organisms (benthos), seabirds, marine mammals, turtles, and so forth.

Discards: That part of the target catch and/or bycatch that is unwanted for one reason or another, and is not used in any way, but is released or thrown back into the sea often as whole organisms, injured or dead. The term "discards" does not include offal or other process waste from the retained catch, which might also be thrown overboard.

Note: The above definitions depend to some extent on what is meant by a target species or target group of species against which fishing effort is directed. A species can move from target to bycatch, or vice versa depending on its size, the season, prevailing market demand or other criteria. One day's bycatch can be tomorrow's target in a volatile market with changing consumer tastes and regional marketing opportunities. For example, specialised fisheries for Nephrops norvegicus (Norway lobster, scampi or Dublin Bay prawn) are based on a species that was once considered worthless.

High-grading: A practice in which only those species or individuals within a mixed species catch that have the greatest market value (usually due to their larger size and, therefore, price) are retained, whilst the less valuable species or individuals, although marketable, are discarded.

Unobserved fishery mortality: Those marine organisms that die unobserved as a result of interaction with the fishing gear irrespective of whether they are captured or not. May include deaths resulting from fish passing through nets, freeing themselves from hooks, ghost fishing, etc.

Bycatch Introduction

Bycatch and the at-sea discarding of fish captured from the ocean, and the associated mortalities, have been recognised as inherent problems in the management of fisheries for hundreds of years.

Efforts to try to reduce bycatch and discarding are not new, either. For many years, countries have set minimum mesh sizes for nets, pots, traps and other gear to minimize catches of juveniles. Regulations have also been made regarding the minimum size of landed species, and time/area restrictions have been placed on certain fisheries. Some countries have introduced legislation to limit particular fishing methods and operational modes for selected waters and regions.

However, the search for solutions to bycatch problems only really began in earnest at the start of the 1990s as a result of growing awareness and concern about the consequences of fishing activities on populations of marine mammals, seabirds and marine turtles. The documentation of, and search for solutions to reduce bycatch and discard levels, and the evolution of management strategies to deal with bycatch has since increased and become a focal point of world fishery management (Alverson et al. 1994).

Nevertheless, better scientific data is urgently required concerning the quality and quantity of bycatch, levels of discards, survival of discards, and impacts of losses resulting from discards on target and non-target marine populations. Such information is vital to the understanding of the regional and international biological, ecological, economic and social impacts of discarding, as well as to finding solutions that reduce discard levels in order to protect marine ecosystems and maintain the productivity of the world's ocean fisheries (Alverson et al. 1994).

Juvenile Fish

Whilst commercial fisheries generally target stocks of adult fish, catches often include small, immature fish, which are either discarded or landed, depending on regulations, quotas and the market.

In the waters around Ireland and adjacent seas (OSPAR region III Celtic Seas), juvenile whiting suffer a high mortality from capture in the Nephrops fishery. High rates of discarding of juvenile whiting in the Irish Sea led to the mandatory use of square mesh panels in UK trawl fleets in 1992 and in Irish vessels in 1994. Juvenile haddock in the Malin Sea are also subject to high mortalities (OSPAR 2000).

Bycatch can include juveniles of both target and non-target species. Juvenile fish are sometimes unable to escape from trawl nets, particularly in fisheries where small mesh nets are used, such as fisheries for shrimp and Nephrops, and in mixed roundfish and flatfish fisheries (OSPAR 2000).

High rates of capture of juvenile whiting in the Irish Sea led in 1992 to the mandatory use of square mesh panels in UK trawl nets. Ireland followed in 1994. Other technical measures introduced to reduce bycatch and discarding of juveniles include sorting panels or grids in fisheries for shrimp and deep-water Pandalus.

OSPAR 2000

Non-fish Species (Marine Mammals, Seabirds and Turtles)

The incidental capture of marine mammals, seabirds and marine turtles in fishing gear can result in significant impacts on their populations. However, although there are a wide variety of known interactions between fisheries and such marine wildlife, the actual levels of bycatch are usually not well known. In general, for most fisheries, only a small portion of marine wildlife bycatch is recorded.

Marine mammal bycatch

Regarding the total bycatch of marine mammals worldwide, in 1994 the FAO stated that: "It seems conservative to conclude that several hundreds of thousands of animals are involved annually" (Alverson et al. 1994).

Small whales, dolphins and porpoises (so-called "small cetaceans") often drown when they become caught in fishing gear, as they cannot come to the surface to breathe. Large whales are more able to break free from nets, but the encounters can cause fatal injuries.

In July 2002 leading cetacean scientists from around the globe estimated that almost 60,000 whales, dolphins and porpoises are killed worldwide each year through entanglement in fishing gear. The scientists, together with WWF, have established the Cetacean Bycatch Action Network to assist governments and fishers in finding solutions to the problem. The global response network will provide scientific expertise and advice to fisheries and governments to help reduce bycatch.

Most reports concerning the entanglement of marine mammals in fishing gear are anecdotal. OSPAR states that: "Without accurate information on population dynamics and true bycatch levels it is difficult to determine whether this mortality is sustainable by the populations concerned" (QSR 2000). Alarmingly, Berrow et al. (1998) state that: "Despite this circumstantial evidence, there has been only one study attempting to quantify marine mammal by-catch in Irish waters," and that: "There have been no studies of entanglement in trawl fisheries in Ireland."

According to OSPAR (2000), in the North-East Atlantic the most common marine mammals that become entangled in fishing gear are porpoises, dolphins and seals.

Harbour porpoises (Phocoena phocoena) appear to be particularly vulnerable to capture in fishing nets, particularly synthetic fibre, and monofilament passive gillnets (set-nets and driftnets). In 1988 the IUCN/World Conservation Union identified the incidental killing of harbour porpoises in gillnets in the North-East Atlantic as a priority for monitoring. A Danish action plan for reducing incidental bycatches of harbour porpoises in its bottom-set gillnet (set-net) fisheries includes measures such as the use of acoustic deterrents, modifications to fishing equipment and regulation of certain types of fisheries.

In order to assess the significance of any bycatch, it is important to know both the rate of annual bycatch, and the size of the population from which that bycatch was taken. However, there have been few studies in the OSPAR area that have acquired the necessary data. Nevertheless, biological considerations indicate that bycatch rates above 1% of harbour porpoise abundance may not be sustainable, and rates above 2% have an unacceptably high risk of unsustainability (ASCOBANS 1997 [1]).

Estimates for the central North Sea (extrapolated from the Danish set-net fisheries) suggest that there was an average annual bycatch of approximately 7,000 harbour porpoises over the period 1994-1998 (OSPAR 2000). This exceeds 2% of the relevant harbour porpoise population, and is clearly non-sustainable.

In the mid-1990s, the bycatch of harbour porpoises on the Celtic Shelf south of Ireland may have exceeded 6% of the harbour porpoise population, although (notes OSPAR) there has been some reduction in fishing effort since the studies were carried out.

Post-mortem examinations of 234 harbour porpoises stranded on the coasts of England and Wales from 1990-1995 found, for those which the cause of death could be identified, that 38% were killed by entrapment in fishing gear; neonatal starvation, pneumonia and generalized infection accounted for a further 31% of harbour porpoise mortalities (OSPAR 2000).

A programme to assess the marine mammal bycatch of the Irish and UK bottom-set gillnet fisheries (primarily targeting hake) on the Celtic Shelf south of Ireland and south-west of Britain was conducted between 1992-1994. In the study, 43 harbour porpoises and four common dolphins (Delphinus delphis) were caught, of which 63% were caught in static nets, 29 per cent in tangle nets and the remainder in nets set over wrecks. The total annual bycatch was estimated to be 2,200 harbour porpoises (representing 6.3% of the estimated Celtic Sea population) and 200 common dolphins (0.3% of the estimated Celtic Sea population). Taking into consideration the limited sample data, there is, nevertheless, "concern about the ability of the harbour porpoise population in the Celtic Sea to sustain an annual bycatch of the magnitude suggested" (OSPAR 2000).

In 2000 OSPAR reported that the effectiveness of acoustic deterrents in reducing harbour porpoise bycatch in the Celtic Shelf bottom-set gillnet fishery for hake was being investigated.

Some oceanic dolphins are particularly vulnerable to pelagic, surface-suspended gillnets (driftnets). Prior to the introduction of EU legislation to restrict the total length of gillnet to 2.5km per vessel [2] and the subsequent June 1998 vote by EU Fisheries Ministers to introduce a ban on driftnet fishing for tuna (which came into effect on 1 January 2002), striped (Stenella coeruleoalba) and common dolphins, among others, were taken in large numbers as bycatch in the albacore tuna (Thunnus alalunga) driftnet fishery operating in the deep waters of the south-west Celtic Sea. (See EU ban on driftnet fishing). It was estimated that the combined French, UK and Irish fleets caught 1,700 common and 2,900 striped dolphins annually (OSPAR 2000).

In just one survey, observers onboard French albacore tuna driftnet vessels operating in the Bay of Biscay and along the Iberian coast during 1992-1993 recorded a bycatch of 573 striped dolphins and 204 common dolphins during 1,420 hauls.

Dolphins and other cetaceans also suffer entrapment in trawl nets. Although the evidence for the entanglement of cetaceans in pelagic trawl nets is circumstantial, coming mainly from stranding records, large pelagic trawlers targeting horse mackerel (Trachurus trachurus) [3] along the shelf edge to the south-west of Ireland are known to catch small cetaceans - primarily white-sided (Lagenorhynchus acutus) and common dolphins and long-fin pilot whales (Globicephala melaena). OSPAR (2000) states that: "The number varies considerably from year to year (eleven in 1992 to 117 in 1994) and the catch rate has been estimated at 1.1 dolphins per 100 hours of towing."

The ability of a trawler to catch cetaceans is strongly influenced by the size of the net opening and the towing speed. The largest trawlers in Ireland fish mackerel and horse-mackerel along the west coast and mainly operate out of Killybegs, Co. Donegal. The results of a complementary study of Dutch freeze trawlers fishing off the west coast of Ireland has shown that they catch dolphins at a rate of 0.04 dolphins per tow, or one dolphin per 93 towing hours (Couperus et al., 1995). It is highly probable that the large Irish trawlers also catch dolphins and it is important to quantify this by-catch.

Berrow et al. 1998

For most fisheries around Ireland, however, the lack of monitoring and assessment means it is generally not possible to determine annual cetacean bycatch mortality rates. OSPAR (2000) states: "Improved estimates of population sizes and knowledge of stock identity and migration are required to enable more accurate assessments of the impact of bycatches on cetacean populations."

Cetacean bycatch in pelagic fisheries in the deep-water west of Ireland (OSPAR Region V Wider Atlantic) poses equally serious problems. According to OSPAR (2000), observers on one-quarter of vessels involved in the French tuna longline fishery between 51-53º N and 10-20º W during 1992 and 1993 recorded large numbers of whales and dolphins being taken as bycatch (see Table 1).

The two seal species which breed in Irish waters — the grey seal (Halichoerus grypus) and common (or harbour) seal (Phoca vitulina) — are both vulnerable to entanglement in a variety of fishing gear through their close proximity to, and interaction with fishing vessels and nets. Other seal species, such as the harp seal (Phoca groenlandica), are incidentally taken by fisheries in more northerly waters.

According to OSPAR (2000), during the 1994/95 herring season, Irish trawlers targeting the inshore herring spawning grounds of the Celtic Sea resulted in an estimated annual catch of 60 grey seals. However, fixed nets used near major seal colonies are believed to pose a greater threat than towed gears. A total of 51 seals (predominantly juveniles) were taken as bycatch by vessels participating in a seal-fishery interaction study off the west coast of Ireland from 1994-1996.

As OSPAR points out, most gillnetting in shallow coastal waters goes unreported because it is carried out by boats less than 10m in length, which are not covered by EU/Irish fishing logbook regulations. "Thus, extrapolating seal mortality rates from reported fishing effort is extremely difficult." In 2000 OSPAR reported that surveys were being carried out to assess the level of seal bycatch to the north-west and south-east of Ireland.

For the most recent details regarding marine mammal catches see Small cetacean bycatch in EU fisheries.

Dolphin escape panels

In July 2002 FIS reported that pelagic fishing boats might be fitted with dolphin escape panels following successful trials of the devices aboard Scottish pair trawlers during 2002, when no dolphins were caught. The trials were set to resume in the 2003 spring English Channel seabass fishery.

However, trials of nets fitted with "pingers" failed to show any benefit from using the electronic acoustic devices.

Previously, scientific observers had logged a severe dolphin bycatch taken by one Scottish pair trawl team, when 52 dolphins were taken in 12 hauls out of a total of 116 hauls over 71 days at sea. That followed a recorded bycatch of 15 dolphins over nine days at sea in 2000, during monitoring by the UK Centre for Environment, Fisheries and Aquaculture Science (CEFAS). Subsequently, the UK Sea Mammal Research Unit (SMRU) began testing new bycatch mitigation measures on a Scottish pair trawl, involving the use of separator grids and an escape hatch for cetaceans. No cases of dolphin bycatch were recorded.

In answer to Parliamentary questions from Green MSP Robin Harper, Scottish deputy fisheries minister Allan Wilson said: "SMRU has also monitored other pelagic fisheries in this area, but has recorded no cases of dolphin bycatch. If the new mitigation measures prove successful, we and [the Department of the Environment, Food and Rural Affairs (DEFRA)] will consider their wider introduction, as part of a joint UK small cetacean bycatch reduction strategy to address bycatch issues across all UK fisheries. The majority of vessels involved in this particular fishery, however, are French. It is therefore important that any mitigation measures are implemented at EU level also and to this end the UK Government has already made contact with the European Commissioner."

Mr Wilson also pointed out that the bycatch measures would form part of Common Fisheries Policy reform. The UK bycatch strategy working group includes the Scottish Executive, other government departments, conservation agencies and the Association of Sea Fisheries Committees (FIS Europe 9/7/02).

Cetacean bycatch in EU waters

An evaluation of the state of knowledge concerning cetacean bycatch, conducted for the European Commission (Spencer et al. 2000), found that the incidental catch ("bycatch") of dolphin and porpoise species in fishing gear is widespread, and it is widely suggested that it threatens the integrity of dolphin and porpoise populations throughout European waters. Despite this, and reflecting the lack of systematic monitoring, there are relatively few records of bycatch events. The small cetacean species at risk are thought to include the harbour porpoise, the common dolphin, the white-sided dolphin, the Atlantic white-beaked dolphin (Lagenorhynchus albirostris) and the bottlenose dolphin (Tursiops truncatus). Other findings include:

• Nearly all types of fishing gear have the potential to incur cetacean bycatch. However, presently in the North Atlantic, those most commonly associated with the incidental catch of cetaceans are gillnets and mid-water trawls.
  
  
• Bycatch of the dolphin species occurs mainly in mid-water trawls, in the North Sea, Celtic Sea and the Bay of Biscay. Harbour porpoises are caught mainly in set gillnets and are vulnerable in the central and northern North Sea, Baltic and Swedish Seas and the Celtic Sea.
  
  
• There is a great deal of conjecture over the way in which small cetaceans become entangled in the fishing gear, which leads to further argument over the most effective way to tackle the problem. Ultimately, most authors agree that dolphins and harbour porpoises can detect gillnets and trawls, that they perceive them as a threat and that the overlap in the diet of the cetacean species and the fish targeted by the fisheries plays a part in the interaction.
  
  
• Estimates of bycatch rates in European waters generally refer to single areas or fisheries. However, in most studies, the status of the cetacean populations is uncertain and it was not possible to quantify bycatch rate or assess its sustainability.
  
  
• Efforts to reduce the bycatch rate include use of a variety of methods combining new technology and changes in fishing strategies.
  
  
• Studies have shown that the longer the soak time of a bottom-set gillnet, the greater the bycatch rate and the poorer the fish catch. Therefore, reduced soak time may be beneficial.
  
  
• Thus far, bycatch reduction devices that enhance the detectability of nets to cetaceans have proved the most successful at reducing the incidental entanglement of non-target species.
  
  
• Many EU directives, regulations, etc. refer to cetaceans and the need for measures to conserve them. However, it is doubtful that this alone will lead to reductions in fishery bycatches, at least in the short-term, due to the time taken for such directives to be incorporated into national law, and the need for monitoring and enforcement.
  
  
• Efforts to conserve cetaceans also include the designation of Special Areas of Conservation under the Habitats Directive (92/43/EEC). However, owing to the extensive ranges of these animals, protection of specific areas is generally unlikely to be an effective approach to their conservation.
  
  
• The US MMPA (Marine Mammal Protection Act) offers a possible model for effective bycatch reduction, requiring collection of data on cetacean population size, measurement of current bycatch rate, explicit statements about acceptable levels of bycatch, implementation of conservation measures (e.g. use of closed areas or seasons, pingers) and monitoring of success in meeting these targets. Important features of the implementation of the MMPA are the involvement of the fishery industry from the start, a legally enforceable requirement for boats to carry observers, and adequate finance for the programme.
  
  
• Present EU laws have not led to establishment of routine programmes for measuring cetacean population status, setting bycatch limits, implementing reduction measures or monitoring the success of such measures. To some extent such activities are currently carried out, piecemeal, by a variety of different bodies, usually on an individual project basis. However, such measures could be implemented within the CFP (Common Fisheries Policy) framework.

The authors of the evaluation conclude, amongst other things, that cetacean bycatch in commercial fisheries "has been shown to be, or is thought to be, unsustainable in many fishing grounds in European waters and it is now imperative that changes be made to the European fisheries management system to ensure that the problem is addressed in the future," and recommend that, to address the problem of bycatch, three main objectives must be met, preferably with financial and legislative support. "Firstly, to determine the extent of the problem in an area or fishery [monitoring programmes], secondly to design and test ways to alleviate the problem [mitigation measures] and, thirdly, to achieve the above with full consideration of the livelihoods of fishermen in question" (Spencer et al. 2000).

For more details see Small cetacean bycatch in EU fisheries.

Impacts on seabirds

Numerous seabirds are taken in gillnet and other fisheries taking place in the North-East Atlantic. The importance of seabird bycatch increases when such takes come from small local populations. Inferences may be drawn from research conducted during the early 1980s on seabird populations in and around Newfoundland (OSPAR 2000). Between 2.1 and 9.3% of various populations of gannets (Sula bassana) were killed annually in gillnet fisheries near Newfoundland. About 12% of Newfoundland's breeding population of razorbills (Alca torda) were killed each year in gillnets, whilst as much as 16.3% of some adult common guillemot (Uria aalge) populations were killed.

Pelagic fisheries in the Atlantic (see Table 2) have been shown to take worrying numbers of seabirds. OSPAR (2000) states that during longlining operations, "if baits are thawed thoroughly and a few simple precautions are taken to prevent birds taking the baits during deployment, far fewer birds are killed and the efficiency of the fishing is improved."

Seabirds may benefit from the bycatch of other species. Several seabird populations in the North-East Atlantic have increased, probably due to a number of concomitant factors, such as better protection, increases in small prey fish, and an increase in forage availability due to fish discards and offal from commercial fishing boats.

Conversely, the removal of large amounts of biomass — of both target and non-target (bycatch) species — from a marine ecosystem decreases the availability of prey and may lead to a sharp fall in seabird numbers.

In the North Sea it is estimated that seabirds consume approximately 50% of all discards (109,000 tonnes) and offal (71,000 tonnes) annually.

OSPAR 2000

IPOA-Seabirds

The FAO International Plan of Action for Reducing Incidental Catch of Seabirds in Longline Fisheries (IPOA-Seabirds) states that: "Seabirds are being incidentally caught in various commercial longline fisheries in the world, and concerns are arising about the impacts of this incidental catch. Incidental catch of seabirds may also have an adverse impact on fishing productivity and profitability."

Key longline fisheries in which incidental catch of seabirds are known to occur include tuna, halibut, Greenland halibut, cod, haddock, tusk and ling in areas of the North Atlantic. The seabird species most frequently taken in the North Atlantic are the fulmars.

Set within the framework of the Code of Conduct for Responsible Fisheries, the objective of the voluntary IPOA-Seabirds is to reduce the incidental catch of seabirds in longline fisheries where this occurs. The IPOA-Seabirds applies to States in the waters of which longline fisheries are being conducted by their own or foreign vessels and to States that conduct longline fisheries on the high seas and in the exclusive economic zones (EEZ) of other States. All concerned States are encouraged to implement it.

Marine turtle bycatch

The FAO (Alverson et al. 1994) has estimated that some 40,000 marine turtles are incidentally captured worldwide each year. Incidental takes of marine turtles in shrimp trawls, largely in the Gulf of Mexico region, have drawn a great deal of attention in recent years. Since marine turtles are very slow to mature, for example, green turtles (Chelonia mydas) may not become reproductively mature until 30-50 years of age, it may take decades to see the effects of management actions to prevent turtle bycatch, such as the introduction of turtle excluder devices (TEDs). Likewise, this long immature period, combined with high natural mortality of eggs and the early life stages, leaves marine turtles populations highly vulnerable to losses from incidental capture in fishing gear.

A number of other fisheries are implicated in marine turtle incidental capture and mortality. However, quantitative data are very hard to come by. According to the FAO, otter trawls, gillnets (both bottom-set and driftnets) and longlines appear to take significant numbers whenever they coexist with turtles.

Mortality rates have been estimated at 42% for turtles incidentally taken by longline gear.

(Alverson et al. 1994

Recreational Fisheries Bycatch

Regarding recreational marine fisheries, the FAO 1994 global assessment of fisheries bycatch and discards notes: "While reliable estimates of the weight of global recreational bycatch are lacking, data collected from US fisheries in 1989 document a total discard of 1.035 billion individuals in association with a landed catch of 651.8 million individuals (1.5 individuals discarded to each fish retained). Clearly, recreational fishery discards would add substantially to estimates of global bycatch removals, and a definitive study of their extent is necessary."

Positive Impacts of Bycatch

Some biological or ecological impacts of bycatch and discards may be considered positive. Bycatch and discarding has the effect of transferring large quantities of otherwise inaccessible biological material from the bottom to the surface, where it is available to surface scavengers. Discards provide readily available forage for surface, midwater, and benthic scavengers including birds, sharks, dolphins, and other marine mammals. Population enhancement of selected species due to discards may, however, be offset by negative (but unobserved) impacts elsewhere. For example, species scavenging in and around fishing gear also increase their own susceptibility to incidental capture.

Discards

In 1994 the Food and Agriculture Organization of the United Nations (FAO) estimated that between 18-39 million tonnes (average 27 million tonnes) of fish are discarded at sea each year in commercial fisheries worldwide, based on a total target catch of about 77 million tonnes (Alverson et al. 1994). These estimates exclude discards from shellfish fisheries, subsistence fisheries, marine aquaculture and recreational fisheries.

In 1996 the FAO revised its annual discard estimate to some 20 million tonnes based on available data for 1994-1995, which suggest a significant reduction in discards occurred between the mid-1980s and the mid-1990s as a result of: 1) a decline in the levels of fishing; 2) time/area closures; 3) new or more selective technologies; 4) greater utilization of bycatch for human consumption and feed for aquaculture and livestock; 5) enforcement of prohibition on discarding by some countries; and 6) a more progressive attitude of fishery managers, user groups and society to the need to resolve problems resulting from discarding (FAO 1996).

As well as being an obvious waste of life, and contributing to overfishing and ecosystem imbalance, such wastage of already captured living marine resources flies in the face of rising world population and hunger, undermining the principles of food security and sustainable development, most recently expressed at the 2002 World Summit on Sustainable Development.

Typically as stocks become fully fished, then overfished and the pressure on the remaining biomass intensifies, huge quantities of undersized fish are caught. If these are too small to be sold or below the minimum legal landing size they are thrown away (discarded). This means that many fish are killed before they have a chance to reproduce and replenish the stock.

The reason for discarding varies. It may simply be a case of dumping unwanted individuals because they are damaged or spoiled, or species because there is no market for them, or may be because they are illegal due to their small size/age, protected status, etc.

The introduction of an annual catch limit (total allowable catch, or TAC) and quota for a species or stock can affect the discard rate, particularly when fishermen opt to maximise their earnings by high-grading (i.e. discarding smaller fish so that they can land a quota of more valuable larger fish) or else are compelled to discard fish species for which the quota has already been filled.

Many fish swim in mixed shoals. Under the current system — in which fishing vessels undertake mixed fisheries by targeting several species in such shoals — once a quota for one species is reached, excess fish of that species are discarded whilst the fishing vessels continue targeting the shoal to capture other species.

Fishermen generally view discarding as a nuisance because it incurs costs (due to time spent sorting and dumping the discards) and generates no revenues.

Bycatch is virtually unavoidable in most fisheries. While improvements in gear selectivity and use have reduced bycatch in many fisheries, and more use is now made of bycatch, this has not eliminated discarding.

North-East Atlantic Bycatch

The level of bycatch and discards in some fisheries in the North-East Atlantic is a major cause for concern. The FAO has estimated that North-East Atlantic discards comprise 13.6% (3.67 million tones) of the world total (27 million tones) (Alverson et al. 1994). Demersal trawl fisheries, particularly those for Nephrops, have significantly high levels of bycatch and discards.

In 1995 an estimated 7,530 tonnes of fish were discarded from the international fleets fishing in the Rockall area alone (Berrow et al. 1998).

Throughout the wider temperate and subarctic North Atlantic region, discards were generally dominated by sublegal and legal sizes of commercially important cods (Gadidae), right-eyed flounders (Pleuronectidae), hakes (Merluccidae), and rockfishes (Scorpaenidae), plus various species of sharks, eel pouts (Zoarcidae), and sculpins (Cottidae) and a wide variety of invertebrates.

Discard problems may be classified into four groups:

i) marketable species too small or otherwise prohibited from landings;

ii) species for which no current market exists, but are caught along with commercial or recreational species;

iii) species-specific fleet sectors discarding another fishery's target species; and

iv) non-fishery bycatch species including marine mammals, turtles and seabirds.

In its Quality Status Report 2000 of the North-East Atlantic, the OSPAR Commission reports that:

• In Nephrops fisheries in the Irish Sea, just under half a tonne of whiting bycatch is discarded for every tonne of Nephrops landed.
  
  
• In certain flatfish fisheries in the North Sea more than half of the weight of the fish caught may be discarded.
  
  
• During the 1990s, about half of the total numbers of whiting and haddock caught by trawlers off the west coast of Scotland were discarded.

Figures on discards of both target and non-target species for the waters around Ireland and adjacent seas (OSPAR Region III Celtic Seas) are "far from complete and are, at best, approximations," according to OSPAR (2000). However, it is estimated that over 13,250 tonnes of demersal and 2,050 tonnes of pelagic fish (15,300 tonnes total) were discarded by the demersal fleets sampled in Region III in 1996. Approximately 65% of the demersal discards comprised whiting, haddock, dogfish (Scyliorhinus canicula) and gurnards, while large numbers of undersized whiting and haddock are discarded in the Malin Sea and Irish Sea.

OSPAR (2000) states that: "During the 1990s, about half of the total quantity of whiting and haddock taken by trawlers off the west coast of Scotland, and of whiting taken by Nephrops trawlers in the Irish Sea, were discarded dead. In 1996, for every tonne of Nephrops landed in the Irish Sea by trawlers from Ireland and Northern Ireland, just under half a tonne of whiting (mostly undersized fish of age three and below) were discarded." Studies conduced between 1992-1994 indicate that 54-67% of immature plaice (age classes 1 and 2) caught in the Irish Sea were discarded, whereas less than 5% of fish above the minimum landing size were discarded.

Discards by pelagic fisheries are just as alarming. In the early-1980s, discards (in ICES sub-areas VI and VII and divisions VIIa,b,d,e) of mackerel ranged from 12,000-62,000 tonnes, and of horse mackerel 1,000-8,000 tonnes.

Norway has introduced a no-discard policy and vessels fishing in the Norwegian exclusive economic zone have to retain the bycatch on board and land it. The amount of bycatch is then deducted from the vessel's quota. The FAO calls this a policy that should be considered by other countries in the area.

At present, only the Netherlands routinely provides information on mackerel and horse mackerel discards from their trawl fisheries in Sub-areas VI and VII. OSPAR states that estimates of discards from Spanish fleets operating in the same areas vary from 0.1 to 8.1% for mackerel and 0.2 to 25.7% for horse mackerel, with the caveat that such a discard rate estimate for one fleet does not necessarily apply to the entire fishery (OSPAR 2000).

Regarding herring fisheries in Region III, OSPAR states that: "Herring discard rates are highest in the roe fisheries, although the rates have declined in recent years due to more accurate targeting of the shoals concerned. Despite substantial catches, there are no indications that discarding has caused problems in the herring fishery in Divisions VIa and VIIb,c. The discard rate of herring in the Irish fleet fishing on spawning grounds in the Celtic Sea has been estimated at approximately 5%" (OSPAR 2000).

OSPAR (2000) provides an estimate — extrapolated from observed capture rates and total fishing effort — for the incidental capture of non-target elasmobranchs by the bottom-set gillnet fishery off Ireland's south coast, of 6,000 sharks, comprising primarily tope, porbeagle and six-gill shark (Hexanchus griseus).

In the open ocean west of Ireland (OSPAR Region V Wider Atlantic), pelagic fisheries for tuna and tuna-like fishes are particularly prone to catching non-target species. A small-scale observer programme run by ICCAT (1997) recorded an extensive list of species taken as bycatch in the Atlantic (see Table 2).

A study of an experimental trawl and longline fishery in the Rockall Trough off the north-west coast of Ireland (Connolly and Kelly 1996) found that bottom trawls resulted in a larger number of species comprising bycatch, and higher discard rates compared to longlining (Berrow et al. 1998).

Bycatch and discarding in the Celtic Sea

Despite the importance of pelagic fish species, which account for over 80% of the total number of fish landed into Irish ports, there is little published information on discarding practices for most Irish trawl fisheries and no study of marine mammal bycatch (Berrow et al. 1998).

A survey of Irish vessels undertaking paired mid-water trawling for herring (Clupea harengus) in the Celtic Sea during the 1994/95 season (Berrow et al. 1998) found that 4.7% of the catch was discarded [4], with discard rates varying throughout the fishing season, from 2.3 to 7.9%.

Of the 20 non-target species identified, whiting (Merlangius merlangus) was the most frequently recorded bycatch fish species, occurring in 84% of tows. Mackerel (Scomber scrombrus) (32%) and cod (Gadus morhua) (30%) were also regularly recorded, but most non-target species occurred in less than 10% of tows: horse mackerel (Trachurus trachurus), megrim (Lepidorhombus whiffiagonis), hake (Merluccius merluccius), red gurnard (Aspitrigla cuculus), grey gurnard (Eutrigla gurnardus), dragonet (Callionynus lyra), conger (Conger conger), dab (Limanda limanda), monkfish (Lophias piscatorius), lesser-spotted dogfish (Scyliorhinus canicula), spurdog (Squalus acanthias), squid (Todoropsis) and octopus (Eledone cirrhosa).

Berrow et al. (1998) state that: "Reasons for discarding at sea varied, but most fish (64%) were discarded owing to market requirements for a high roe content, with fishermen only landing high-quality fish to maximise their profits from quota restrictions. One catch was discarded owing to a high proportion of small herring in the catch and one owing to a high proportion of mackerel (6% of all fish in sample), which may have resulted in the whole catch being rejected on landing. Both of these catches were very small (1 and 2 tonnes) and not worth the expense or time of landing, so they were discarded."

The vessel skippers generally considered discarding to be low during the 1994/95 season, owing to the low abundance of herring in traditional spawning areas. "As fish were harder to catch than usual, most fish were landed, and only towards the end of the fishing season did discarding increase, as fisheries officers from the Department of the Marine and Natural Resources (the regulatory authority) restricted the amount of fish each vessel was allowed to land to ensure that the TAC for the season was not exceeded."

Based on reports from fishermen rather than data, the ICES Herring Working Group (1996) assumes a discard rate of 10% for the Celtic Sea fishery.

Significantly, Berrow et al. (1998) concluded that there was no relationship between fishing effort and discarding, "which may have identified factors to help minimise this practice".

Of marine mammals, 4 grey seals (Halichoerus grypus) were caught during the study, near to the Saltee Islands, at a rate of one per 317.5 tonnes of fish, or 0.05 seals per trawl gear tow. All seals were adults measuring 1.7-1.9m. On-site post-mortem examination showed that both seals had been feeding on herring at the time of death.

This catch rate extrapolates to around 60 seals caught in the fishery, which is unacceptable, whether or not it has a significant impact on the Irish seal population.

The observers noted that: "Grey seals were regularly seen feeding on fish during hauling and were often seen diving between the pair trawlers during towing, which suggests that they can usually avoid the net and only occasionally become entangled."

It is believed that the grey seal breeding population along the south coast comprises some 2,000 individuals in small colonies of less than 60 animals. The Saltee Islands in County Wexford are a known breeding site where up to 60 pups have been born in recent years. The herring fishery operates during the grey seals' post-breeding dispersal phase, an important time when the seals return to feeding at sea to accumulate fat reserves lost during breeding, before the main winter storms.

Berrow et al. (1998) concluded that more information on population structure, feeding range and immigration is required before a proper assessment of this bycatch mortality can be made.

Alarmingly, the above study was the first attempt to quantify marine mammal bycatch in a trawl fishery in Ireland and the most extensive study of discarding in the herring fishery.

Deep-sea fisheries bycatch

Because deep-water fish generally live in highly diverse multispecies assemblages, combined with the indiscriminate character (low selectivity) of the trawl gear used to target them, and the fact that there are markets for only a few of the species, the bycatch and discard rates of deep-water mixed fisheries tend to be high. An analysis of the species composition of the discards from Scottish and French deep-water fleets recorded 82 species (OSPAR 2000 ).

The majority of deep-living fish are dead by the time they arrive on deck. Despite contributing to fishing mortality on the stock, they are rarely recorded. OSPAR (2000) states that a study of a French deep-water fishery around Rockall showed that similar quantities of fish were being discarded as were being landed.

In OSPAR Region V (Wider Atlantic), the impacts of overfishing "are being exacerbated by the general disregard of size restrictions on the fish that may be landed" (OSPAR 2000).

Impacts on Benthic Habitats and Communities

Bycatch and discards can lead to changes in seabed (benthic) community structure. Apart from the habitat modification resulting from the gear itself [5], or the issue of unobserved gear-related fishing mortalities [6], discarding leads to obvious mortalities when benthic species (benthos) are brought to the surface and then discarded, often to be consumed by scavengers in the water column or on the bottom.

Clearly, the benthic community structure may change if a greater proportion of the community is comprised of scavenger or decomposer species attracted to the area. The discard at sea of bycatch and processing waste (offal) may result in the "poisoning" of fishing grounds when, if sufficient quantities settle to the bottom, decomposition processes consume enough oxygen to introduce anaerobic conditions (Alverson et al. 1994). "Spoiling" is another indirect effect of discards on the benthic community. In the North-East Atlantic Nephrops (scampi) fishery, individuals are often "headed" at-sea and the heads discarded overboard. The presence of these heads on the bottom has been found to inhibit Nephrops bottom movements, thus "spoiling" the ground.

Demersal fishing gear, used to capture fish and shellfish living on or near the seabed, can cause death or severe damage to benthos as well as physical disturbance to sediments. The magnitude of the impact is related to towing speed, gear size and weight, the type of substrate (mud, sand, gravel, etc.), and local hydrodynamic factors. Trawling, however, is often patchy and the impact is generally less severe in areas naturally impacted by storms and wave disturbance.

Otter trawl boards can penetrate soft sediment to a depth of 6-20cm, whilst the tickler chains from beam trawls plough sediments to a depth of 4-8cm. The effects of different types of fishing gear in terms of seabed disturbance and species affected, in the Celtic Seas (OSPAR Region III) are given in Table 5 (word doc).

OSPAR (2000) states that: "Deep-water benthic habitats tend to be very susceptible to the impact of trawling, due to their slow regeneration rate. A 1994 survey indicated that up to 25% of the Irish Sea seabed is disturbed by otter trawling. The Irish otter trawl fleet alone trawls the Irish Sea Nephrops grounds up to five times per year. Disturbance of the seabed by fishing gear can also change the species and size composition of benthos. For example, in areas of the North Sea, where fishing disturbance has occurred over a long period of time, there has been a shift in benthic diversity and composition from larger more long-lived benthic species to smaller more opportunistic species."

Recent investigations along the continental shelf edge west of Norway and Scotland have shown extensive damage caused to fragile cold-water coral reefs by deep-water trawling (OSPAR 2000).

Biological and Ecological Impacts

There is widespread concern over the contribution of bycatch and discards to overfishing and marine ecosystem imbalance. The FAO (Alverson et al. 1994) states that: "a growing body of literature does support the conclusion that for some species and regions of the world, biological and ecological impacts are discernible."

Biological and ecological impacts as well as other impacts resulting from discards will vary between species depending on the quantities taken, the mortality/survival rates of discarded species, and the population characteristics and life histories of impacted species (Alverson et al. 1994).

Large quantities or numbers of discards do not necessarily equate with significant biological or ecological impacts. Conversely, to presume effects are minimal or absent because discard quantities or rates are low may also be misleading. Impact studies which bridge the gap between discard quantities and the consequences of these losses at the population and community levels are a necessary prerequisite to improvements in our understanding of the effect of fishery discards on biological populations and marine environments.

Alverson et al. 1994

The ultimate consequence of discarding depends on the mortalities imposed on the relevant populations. Over many years, discard mortality may affect species abundance and stock structure, and must be taken into account in stock assessments. Inferences about the level of discard mortality may be drawn from a 1990 report on discard mortalities for the North-East Pacific (NRC 1990), which contains mortality data for halibut, crab, and salmon:

• Halibut discard mortality estimates range from 2% reported in longline fisheries to 100% in several trawl and pot fisheries. As much as 50-100% of all halibut caught in shrimp trawls die, while 31-100% of all halibut incidentally taken in crab pots are expected to die. Significantly, in one study, smaller sublegal halibut (under 80cm in length) suffered a substantially higher mortality rate (72%) in the British Columbian trawl fishery than did larger (over 80cm) halibut (45%).
  
  
• Mortality estimates for trawl-caught crab species range from 2-82%, while Finally, 0-50% of all crabs taken with longline fisheries are expected to die.
  
  
• Salmon mortality rates range from 8% for legal-sized chinook (Oncorhynchus tshawytscha) taken in troll fisheries to 100% for salmon taken in longline and trawl operations. Up to 50-90% of all legal- and illegal-sized chinook caught with purse seine nets die. As would be expected, barbed hooks raise mortality substantially. Some 77% of juvenile coho (Oncorhynchus kisutch) caught on barbed hooks died, compared to only a 33% when caught on barbless hooks. Studies have also demonstrated that mortality rates range from 6-11% for salmon hooked and released by recreational anglers.

Many researchers believe that survival rates for fish, particularly those species left floating on the sea surface, are low. For species such as cods and whiting whose air bladders expand and trap them at the surface, survival rates are expected to be very low. Factors contributing to mortality of discards include the:

• size of specimens;
• character of the gear deployed;
• catch sorting methods and duration of sorting time;
• fishing time;
• size of catch for trawls and seines (i.e. constriction and compression within the net bag, leading to physical injury and suffocation);
• associated species in the catch; and
• environmental conditions (Alverson et al. 1994).

The relative impact of discards on target and non-target populations may differ significantly, depending on the life history features of the impacted species. For example, species having low reproductive rates, elevated parental care, and low rates of natural mortality could reasonably be expected to suffer greater impacts. Thus, the impacts of high discard numbers on cod, pollock and flounder may be less than relatively low discard numbers on marine mammals, turtles, sharks, skates, and deep-water species, etc.

Sizable amounts of discards may — but not always — result in significant impacts at the population level. For example, in the Irish Sea there is evidence that bycatch in the major groundfish fisheries was largely responsible for the decline and scarcity of the once abundant common skate (Raja batis).

Bycatch and discards (due to differential quantities and rates of mortalities between target and non-target species) can alter the character of species assemblages. Such shifts have the potential to alter predator/prey relationships, increase food for scavengers, modify the structure and function of benthic communities (as the result of oxygen depletion), and increase competition between fishermen, marine mammals, and other sea life for available resources.

Discarded fish do not normally survive to become adults, and so represent an additional mortality to the stocks. Discards also alter the competitive relationships within the communities by favouring the scavenging species.

A worrying, and as yet unquantified, aspect of ecosystem imbalance is the effect of removing top predators as a result of fishing activity. The absence of controls by top predators is likely to have profound effects on the structure of marine communities. The discarding of bycatch and offal will also upset competitive balances within the communities by favouring the scavenging species.

Economic Impacts

Bycatch and discards can result in considerable economic losses including those associated with discards of species of commercial value to other fisheries, discards of undersized or other non-legal individuals, and discards of non-target species of little commercial value. There are also indirect costs including the fisheries management expenditures on bycatch-related monitoring and prevention (observer costs, enforcement expenses), lost fishing opportunities due to premature closures of target fisheries following the attainment of bycatch caps or overfishing of stocks, modifications to fishing gear and practices to reduce bycatch and discarding, and increases in onboard sorting and handling times.

Fisheries Management

Contribution of TACs to the problem

The overall objective of fisheries management is to ensure long-term, sustainable and efficient use of fisheries resources. The principal framework instrument within the European Union (EU) in this regard is the Common Fisheries Policy (CFP), and the most widely used tool is the yearly setting of annual catch limits, known as total allowable catches (TACs), and national quotas for stocks of the main commercial species.

The TAC system is also used by non-EU countries such as Norway and Iceland for fisheries management in their waters. Beyond the exclusive economic zones of both EU and non-EU countries, in the international waters (high seas) of the North-East Atlantic, the regional fisheries organisations — the North-East Atlantic Fisheries Commission (NEAFC) and the International Commission for the Conservation of Atlantic Tunas (ICCAT) — also use the TAC system to manage highly migratory species and straddling stocks.

Under the TAC system, an upper limit is imposed on the landings of each stock. Prior to the January 2003 implementation of CFP reforms including the introduction of medium-term multiannual management plans for stocks, TACs are established each year on the basis of advice from the ICES Advisory Committee on Fishery Management (ACFM). They are divided into fixed percentage quotas allocated to each state participating in the fishery.

OSPAR (2000) states that: "The TAC system is an indirect method of fishing effort control and does not directly take into account the fact that large quantities of fish are discarded. Without sufficient direct controls on the amount of fishing effort, fish caught in excess of the TAC have been landed or reported as having been caught, in another division. This practice contributed to the deterioration in catch statistics, and the stock assessments which depend upon them."

The advice from ICES is intended to provide a precautionary approach to fisheries management. OSPAR (2000) states that: "As a means to achieve this, ICES has suggested precautionary reference points for spawning stock biomass and fishing mortality. However, these precautionary levels are relevant for single stocks and may not be considered as being precautionary with respect to multi-species interactions nor to wider ecosystem effects. In the management of fisheries resources, social and economic considerations also need to be taken into account."

In June 2000, to try to improve on this situation, and take a more wide-ranging approach to fisheries assessment, ICES established the Working Group on Fishery Systems (WGFS). The main aim of the group is to develop a framework and methodology for the analysis of fishery systems performance [7]. A fisheries system includes the fish stock, the fishermen, the scientists assessing the fish stock, and the managers who regulate the fishery. Taking a broader approach, the WGFS will develop new methods of assessing the whole fisheries system, whilst at the same time addressing biological, economic, and social concerns.

The accuracy of annual stock assessments and TACs depends upon the quality and comprehensiveness of catch data. Illegal landings and unrecorded discards undermine the accuracy of stock assessments and thus the TACs. As we have seen above, the lack of effective programmes to monitor fisheries for bycatch and discards means that inadequate data are available for use in assessing stocks.

Under the CFP, EU fleets are obliged to discard undersized fish — a situation exacerbated by the discarding of commercial sized fish captured in excess of quota allowances, and high-grading to maximise economic returns from the catch. The OSPAR Commission states that: "Occasionally whole catches may be discarded because they are under the marketable size" (OSPAR 2000). In stark contrast, over a decade ago, the Norwegian Government introduced regulations prohibiting the discarding of commercially important fish.

From a management perspective, the idea of banning discards is that since the discarded fish have a negligible chance of survival, it is better that they are included in the fishing mortality figures on which TACs estimates are based (Alverson et al. 1994).

The Norwegian system attempts to reduce mortality of "illegal" fish by reducing their capture rather than reducing landings of "illegal" specimens. The initiative has been coupled with a comprehensive monitoring and surveillance programme, and a system whereby fishing areas can be opened and closed when bycatch rates become excessive.

The FAO (Alverson et al. 1994) states that: "Although anecdotal evidence suggests that discarding still occurs it seems to have stimulated the further development and acceptance by the fishing industry of selective fishing gears. The use of selective gears has now become compulsory in a number of Norwegian fisheries. Illegal fish that is landed is sold through the fishermen's sales organisations but the revenue from sales remains in the sales organisation rather than being credited to the fishermen's account thus acting as a disincentive to capture."

Technical conservation measures

The TAC system is complemented by technical conservation measures (TCMs), which are designed to control aspects of the fishery such as mesh size [8] net geometry, restrictions on the way gears are rigged, minimum size limits for landings, bycatch limits, closed seasons, closed areas and gear-restricted areas. Enforcement of the fishers' adherence to TCM regulations is a national responsibility and is assisted by, for example, vessel inventories and licences, logbook regulations and satellite monitoring.

A revised package of TCMs, which came into force in the EU on 1 January 2000, aims to improve gear selectivity and thereby reduce discards. They include the mandatory introduction of square mesh panels into certain nets, limitations on twine and rules on gear construction. In addition, specific controls were introduced to deal with the problem of cetacean bycatch; and, as from 1 January 2002, the use of high seas driftnets to catch tuna and other large pelagic species is prohibited (OSPAR 2000). However, the European Commission admits that these will "only partially remedy the current problems" (European Commission 2001).

For many stocks, the authorized mesh sizes remain too small for the protection of juveniles, and compliance with the regulations is poor because of the complexity of the rules.

Solutions

Effective solutions to the problem of bycatch and discards are likely to entail a combination of technological, economic and legal components, and involve systems for monitoring, control and surveillance (enforcement) (Alverson et al. 1994).

It is becoming more widely recognised that efforts to reduce bycatch and discards levels should involve a wide range of stakeholders, such as the fishers, representatives of environmental groups, and residents of areas affected by the fisheries, as well as fisheries managers, relevant scientists and gear technicians, in developing mitigation strategies for fisheries. Over the past decade, strategies to attempt to deal with bycatch and discards efforts have focused on:

• Limitations or bans on use of particular gear technology.
  
  
• Experimental approaches to improving gear selectivity; development of gear that takes advantage of behavioural differences between species; and technical conservation measures (TCMs) regarding gear specification and deployment.
  
  
• New technology such as reflective nets, acoustic scaring devices (pingers).
  
  
• Overall effort reduction.
  
  
• Incentive/disincentive programmes.
  
  
• Individual transferable quotas (ITQs) that move responsibility for bycatch reduction to individual vessel level.
  
  
• Time/area closures and fishing activity restrictions.
  
  
• Marine Protected Areas.
  
  
• Mitigation plans for individual fisheries.
  
  
• Regulation of fishing methods.
  
  
• Discard reduction through use of a broader spectrum of the catch.

These mitigation strategies have worked with varying degrees of success depending on the species being managed and the willingness of industry to work toward positive solutions. In many cases, market opportunities for bycatch species have also been expanded, thereby increasing the retention and landings of catch fractions previously discarded. In some cases, technical "solutions" have generated unexpected side effects that impair their effectiveness or even cause significant negative impacts.

Gear-based solutions

Banning use of gear types for specified fisheries
The FAO (Alverson et al. 1994) states that: "Reduction in discard levels through regulations making the use of certain gear types illegal, like high seas driftnets, or setting quotas on the quantities of bycatch to be taken, can quickly terminate discard problems or limit the extent of discard mortality". From the standpoint of fishing interests, a preferable solution is the reduction in the capture and discard of species or sizes of species through use of more selective fishing gears, time/area fishing strategies, or vessel incentive programmes.

Reduction in discards using gear selectivity
The functional aspect of gear selectivity is based on the opportunity for escape provided by the gear. This is principally achieved through increasing mesh size to minimise the mortality of juvenile fish. Other selectivity improvements include the use of square mesh panels, various partitions, escape panels, minimum hook sizes in longlines, and modifications to the way in which gear is rigged.

Reductions in discards based on behavioural differences between species
Considerable research has gone into the design of selective gears that take advantage of the behavioural differences between species. One such device increasingly being deployed in the North Atlantic is the "Nordmøre grate" — a rigid bar, solid grid separator trawl for Pandalid shrimps — that has a high separation success in sorting out roundfish such as cod and haddock. However, the use of rigid separator trawls for groundfish species to reduce bycatch of flatfish has, so far, proved less successful.

Reductions in bycatch using new technology
For details of how such devices as pingers and reflective nets are being used to minimise bycatch of harbour porpoises and other small cetaceans, see Small cetacean bycatch in EU fisheries.

Regulatory-based solutions

Overall effort reduction
Any reduction in fishing effort will reduce bycatch. The FAO has stated that: "Short of an outright ban on fishing, no action would likely contribute more to the resolution of bycatch problems than the reduction of fishing effort" (Alverson et al. 1994). For many fisheries suffering from growth overfishing, a reduction in directed effort may be the most straightforward means of reducing bycatch and improving fisheries conservation and management. With this in mind, ICES recently noted that the European Commission proposals for reform of the Common Fisheries Policy include proposals to further reduce effort in nearly all fisheries in EU waters (ICES 2002).

Quick solutions to the bycatch problem are unlikely. Instead, a concerted national and international effort that will take money and time is necessary. A critical component of such action will be the reduction in effort levels from today's excessive amounts to quantities which will avoid conservation and ecological problems and will efficiently harvest the sea's resources.

FAO global assessment of bycatch and discards, 1994

Use of incentive and disincentive programmes
It has been suggested that bycatch and discard problems can best be resolved through placing responsibility at the individual vessel level, by applying incentive/disincentive programmes. The FAO (Alverson et al. 1994) states that: "Solutions are founded on the premise that given incentives, individuals will use their knowledge of gear and the fishing grounds to reduce the capture of unwanted species and maximize their catch of target species."

General experience suggests that one incentive that will reduce discards is to create viable markets for incidental catch. However, the incentive not to discard because the potential discard has a value must be balanced by a disincentive to increase bycatch rates to increase profits. Clearly, comprehensive enforcement is necessary to ensure compliance with the disincentive aspect.

Achieving the appropriate mix of incentives and disincentives may be particularly difficult in some fisheries (e.g. where complex multispecies assemblages mean it is virtually impossible to eliminate the bycatch of some non-target species), especially where there are political and legal implications. It is imperative that any incentive/disincentive programme is fair, with tangible results for the individual fishermen, as well as effective in reducing bycatch and discards.

Individual transferable quotas
Unlike open-entry management systems, individual transferable quotas (ITQs) attempt to address head-on the challenge presented by the short-term perspective of most fishers: short-term economic gain, leading to waste and inefficiency, instead of long-term benefits accruing from more restrained approaches (e.g. next month's boat payments are of more immediate concern than next year's stock size or the fishery's viability the year after that). By relating tomorrow's fishing opportunity to today's actions, ITQs begin to change the time horizons of fishers from short- to long-term. In so doing, they may create the opportunity for resolution of the bycatch problem (Alverson et al. 1994).

The FAO (Alverson et al. 1994) states that:

"ITQs provide ownership rights to the fishery resource. As with other property, if it is well taken care of, its value will generally strengthen. If abused, its value may very well fall. ITQs are based on the premise that fishers who own a portion of the fishery resource will be prone to use it in a manner enhancing rather than detracting from its value. Effort limitation and all of its advantages are a necessary part of a successful ITQ program. The transferability of quota permits a distribution of fishing access to those who best can use it and to dismiss excess effort in favor of economic efficiency.

Although few ITQ systems have been implemented, those which are in place have been generally successful, aside from an often stormy period of transition and adaptation to the new approach. Most ITQs have been designed with the control of target catch in mind. Nevertheless, ready application of ITQs to bycatch management can be made. ITQs for bycatch might not only control the aggregate discard levels but also permit the distribution of bycatch to the most efficient users of the resource. If a given vessel runs out of bycatch quota, additional amounts can be purchased from boats with quota remaining. Of course, as remaining bycatch quota becomes more scarce, the per unit value of that quota increases and the true value of bycatch to the fishing process becomes evident. Boats which have not fished cleanly are now forced to purchase bycatch quota at market values in order to continue to fish. Vessels which have experienced low bycatch rates throughout the fishing season have quota remaining either to sell or to use themselves until the quota or the target species catch levels are reached.

Bycatch ITQ systems are thus an amalgamation of effort reduction and incentive/disincentive programs. At worst, effort is capped in order to introduce an ITQ. At best, it is reduced through buy-back programs. Strong and unavoidable economic incentives emerge to fish cleanly in order to continue to fish when other operations have been terminated. Disincentives linked to lost fishing opportunity are also obvious.

Unfortunately, there are also downsides of ITQ systems. Management and regulatory costs associated with them can prove expensive. Opportunities for entry of young fishers may be limited by the high costs of obtaining the necessary permits and quotas. High-grading and mislabelling can be considerable. So the applicability of an ITQ system and its contribution to bycatch reduction must be assessed on a case-by-case basis.

But because of its inherent advantages (an implicit drop in fishing effort, tangible bycatch reduction incentives, definition of the true costs of bycatch, a transition from a short- to long-term planning horizon), from the perspective of reduced bycatch, ITQs appear to us to be an appropriate management strategy if they can be properly managed and enforced. Clearly, effort reduction and significant gains in lowering bycatch could be achieved, but without adequate incentives or disincentives, the success of effort reduction programs will be incomplete. And finally, if fishers' perspectives remain on the short-term, battles will continue to be fought about the appropriateness of particular incentives and disincentives.

This integrative capability makes ITQs all the more difficult to put into place. Managers who attempt to do so are attempting to bring not one or two pieces of the puzzle together, but rather the whole package. To do so successfully will require as much cooperation and consent from industry and non-industry groups and as little self-serving political manoeuvring as possible."

Time/area solutions to bycatch and discards
In addition to bycatch mitigation resulting from the employment of appropriate mesh, hooks, net designs, new fishing gears and improved fishing methods, reductions in bycatch and discards can be achieved through time/area control of fishing activities. Time/area management strategies take advantage of the naturally occurring variations between the occurrence of target and bycatch species in an area. Closed areas are used in many parts of the world to control bycatch mortalities. By closing areas to fishing or imposing certain regulations on particular fisheries (on a year-round, seasonal, days-of-the-week, or diurnal basis) then certain species or species assemblages can be afforded protection. In practice, however, it is difficult to establish strategies that consistently meet the bycatch reduction objectives.

Marine Protected Areas
Marine Protected Areas (MPAs) are conceptually different from fishery time/area closures in that they are established for conserving marine life (and sometimes landscapes) rather than specifically to deal with fisheries impacts.

Numerous international, regional and national instruments require or advocate the establishment of "representative" networks of MPAs. Most recently, the Plan of Implementation resulting from World Summit on Sustainable Development, Johannesburg 2002, commits countries to "Develop and facilitate the use of diverse approaches and tools, including the ecosystem approach, the elimination of destructive fishing practices, the establishment of marine protected areas consistent with international law and based on scientific information, including representative networks by 2012 and time/area closures for the protection of nursery grounds and periods…" (Paragraph 31c).

Regionally, in order to implement the Convention on Biological Diversity, and specifically the Jakarta Mandate on the Conservation and Sustainable Use of Marine and Coastal Biological Diversity, the OSPAR Commission is co-ordinating the development of a representative network of MPAs in the North-East Atlantic.

The EU Habitats (92/43/EEC) and Birds (79/409/EC) Directives require Member States to establish areas to protect certain marine life. Under the Habitats Directive, species requiring such protection include the harbour porpoise and bottlenose dolphin. Management plans are required for these areas, and these will inevitably include consideration of the management of fisheries.

At the national level, Ireland has yet to begin to properly address the development of MPAs.

Mitigation plans for individual fisheries
To be effective, strategies to reduce bycatch need to be tailored for individual fisheries and circumstances. In the USA, where bycatch reduction is mandatory in a number of fisheries, "take reduction teams" are established to develop overall mitigation strategies. These teams include a wide range of stakeholders, such as managers, representatives of environmental groups, and residents of areas affected by the fisheries along with the fishers, relevant scientists, and gear technicians. The teams are under pressure whereby, if the team fails to reach a consensus, then the US Secretary of Commerce will impose a plan.

ICES (2002) states: "This model may not be suitable for the substantially more complex, multinational fisheries in EU waters, but the principle of bringing relevant scientists and fishers together should not be lost if any mitigation is to be effective. Similarly, the principle of timetabled default management options in the absence of effective implementation of mitigation measures is also something that could usefully be adopted in a European context, if by-catch reduction across national fleets is to be effective."

Regulation of fishing methods
Reductions in bycatch and discards levels may follow implementation of regulations — including in the form of established bycatch quotas — based on managerial, political, or public views that observed levels are unacceptable because of: 1) the perceived biological or ecological impacts to marine resources or the environment; 2) economic impacts generated by one sector of the industry on another; and 3) ethical concerns (Alverson et al. 1994).

However, the FAO points out that the problem may be aggravated by regulatory regimes that: 1) use time/area controls to mitigate losses to one species, but do not consider bycatch and discards effects on other species in more intensely fished alternate areas, or in the same areas by alternative fishing gears or methods; 2) allow fishing effort to greatly exceed that required to attain maximum sustainable yield (MSY) levels; 3) allocate catch of a particular species to a single gear type without regard to, and the time/area catch composition of, different gear types; and 4) promote "Olympic" type fishing activities (i.e. the highly competitive race between vessels and fleets for few available resources).

Discard reduction through use of a broader spectrum of the catch
Numerous stakeholders, particularly those concerned with food security issues, have proposed that the discards problem can be resolved, at least in part, through broader use of the species being discarded. However, attempts to encourage fishers and markets to exploit and utilise a wider range of species, and even smaller sized fish, have potential to backfire and negate conservation goals including where overfishing is already a problem, and if the bycatch mortality results in ecosystem imbalance.

Whilst complete elimination of discards appears to be an unrealistic goal, the use of discards for food and increased food security will continue to have a role to play in elimination of wastage. For example, where fish is incidentally caught in waters adjacent to countries that are short of protein resources for feeding their people, the (non-profit) use of that fish to assist in alleviating hunger should be a high priority.

Banning discards
Over the last decade, different governments and fisheries administrations around the world have instituted schemes making it obligatory for bycatch to be landed. This has either been in the form of the requirement for a certain percentage of bycatch to be landed, or a complete ban on discards of particular species. However, the enforced landing of bycatch (banning of discards) brings its own problems:

1) Should the landed fish be dumped (is this any better than discarding at sea), or should the fish be utilised? Enforced landing allows bycatch to be recorded, resulting in better data on which to base management decisions and the control of subsequent fishing activities to conserve stocks and sustain the fishery. At this stage, the fish are dead and detached from the marine ecosystem. In the interests of food security and non-wastage of animal protein it would seem appropriate that the fish be utilised.

2) However, if the bycatch is to be utilised, should the fishermen responsible be paid for the "illegal" fish? To do so might encourage, or at least not deter, the subsequent capture of more of the non-target, illegal or otherwise undesirable species. A number of different approaches have been taken, including normal pricing structures, no monetary value, and others in between.

3) If the bycatch is to be utilised, should the fish processor have to pay for the fish? If the fishermen are to be paid for this "illegal" fish, then the processor is in effect an "accomplice" to the encouragement of the capture of non-target species in the first place, if full market value is paid by the processor to the fishermen.

4) Will utilisation of the bycatch create a market for the species and thus encourage rather than discourage further capture of similar species? Market pressures and mechanisms run the risk of creating market forces for "illegal" fish, so encouraging rather than discouraging their capture.

The FAO (Alverson et al. 1994) adds that: "These questions therefore raise others, such as: if a ban on discarding is to be instituted what incentives should be in place to encourage compliance or conversely what disincentives should there be to non-compliance. There is a danger that if full market price is paid for fish which contravenes conservation regulations, fishermen will be encouraged to fish for it more. On the other hand if fishermen are not compensated at all for the extra work and costs of landing the full catch then there will be a temptation on the part of the fishermen to continue discarding at sea. Thus there needs to be balance between over compensation and encouraging trade and under compensation and thus encouraging discarding. This of course assumes that there is a market for the products of a discard ban and they have a value."

Enforcement

Whether technical or administrative or both, strategy solutions to the problem of bycatch and discarding require monitoring, control and surveillance (i.e. enforcement) if they are to be effective. Enforcement measures are costly to implement. But the costs must be weighed against the true costs (intrinsic and social as well as economic) to species, ecosystems, fisheries, fishing communities and society in general of inaction or ineffective mitigation measures.

Bycatch, Discards and Reform of the CFP

The European Commission's Green Paper on the future of the Common Fisheries Policy (CFP) states that options and preferences for strengthening and improving conservation policy include: "Adoption of stronger technical measures to protect juveniles and to reduce discards including pilot projects for measures not applied until now such as discard bans" (European Commission 2001).

Further, section 5.1.2 (Technical measures) states that: "There is a need to adopt more effective rules. The introduction and promotion of the use of selectivity devices that reduce or eliminate by-catches of non-target species and of fishing methods that have a reduced physical impact on the environment should certainly contribute to improving the current situation. Technical measures should also better take into account the environmental dimension. For example, the closure of a given zone and the exclusion of any fishing activity may be of limited use in terms of fisheries management but it can ensure the protection of an ecologically sensitive and important area for non-target species.

There is also a need to explore the usefulness of measures which have not been applied until now, such as discard bans in some fisheries which are easy to control and real-time closures of certain areas. Other possible solutions could also be explored such as the consideration of a percentage of by-catch species as part of the TACs, as is done in the Northwest Atlantic Fisheries Organisation (NAFO). Pilot projects along these lines could be easily tried."

Commission proposals
In May 2002, the European Commission published proposals for reform of the CFP. Regarding conservation they included an Action Plan to integrate environmental protection requirements into the Common Fisheries Policy COM(02)186; an Action Plan on discards; and a Code of Conduct for responsible fisheries in Europe.

In particular, the Commission proposed the establishmwnt of a long-term approach to conserving fish stocks and protecting the environment: "That would mean doing away with the annual ritual of setting fishing quotas and to set, instead, long-term management plans for fish stocks, based on sound scientific data. The approach would be differentiated, taking into account the different situations of stocks in different areas. The proposed plans would include medium-term targets for the stocks concerned (in terms of their biomass) and rules for setting catch limits and fishing effort limits each year, designed to achieve the targets. Catches would be calculated in relation to the maximum amount of fish that can be removed by fishing to ensure that a sufficient quantity of adult fish — well above the minimum biological acceptable limits — remains in the stock concerned. Such an approach would reduce the abrupt changes in TACs from one year to the other which prevent fishermen from planning their fishing activities.

The Commission proposes that the multi-annual strategy, i.e. the long-term objectives to be achieved and rules for setting annual limits, be decided by Council while the annual TACs be set according to the agreed strategy by the Commission assisted by a Management Committee" (European Commission 2002a).

As part of the Commission's proposed new multi-annual framework for conservation of resources and management of fisheries, multi-annual management plans for commercial stocks or group of stocks will: "where appropriate, establish rules for the protection of non-commercial fish species, in particular cetaceans and other marine mammals, and seabirds" (European Commission 2002b).

Regarding strengthening technical measures, the Commission states (2002b) that: "With a view to increasing yields from fisheries and to improving their sustainability and reducing their impact on the ecosystem, the Commission will come forward with regulatory measures to reduce catches of younger fish, by-catches in mixed fisheries and discards. Such measures will include:

• the introduction of more selective fishing gear, such as nets with larger meshes, square-mesh panels, separator grids, and changes in design and rigging of such gear in order to improve selectivity;
• restrictions on fishing to protect juvenile fish, sensitive non-target species and habitats;
• minimum landing sizes in line with the selectivity of the gear concerned;
• "discard ban trials" in which representative samples of fishing vessels would be encouraged by economic incentives to retain their entire catch;
• the targeting of economic incentives for the use of more selective fishing practices.

The measures introduced will be kept under review and proposals introduced as needed in the light of changes in fish stocks, scientific developments, changes in fishing practices and the development of new fishing gear.

The Commission will also invite the fishing industry to develop, as a supplement to Community rules, a voluntary code of conduct intended to reduce discarding. In addition, the Commission will develop scientific and technical monitoring of fishing practices that result in discarding, and will continue to seek advice on mitigating measures. The Commission will report periodically on progress achieved in reducing discards."

Regarding incorporating environmental concerns into fisheries management, the Commission: "advocates a long-term strategy to promote the protection of vulnerable species, such as cetaceans, sharks, skates and rays and marine birds, and habitats by such means as gear restrictions and closed areas and seasons. As first steps, the Commission will propose during 2002 measures to ensure the protection of sharks, within the FAO International Plan of Action on this subject, including the prohibition of "finning" (the removal of fins and discarding of carcasses) of sharks in Community waters, measures to reduce by-catch of cetaceans and a conservation programme concerning sea-birds" (European Commission 2002b).

In its "roadmap" to the reform of the Common Fisheries Policy, the European Commission (2002b) states that, with regard to the repercussion of the conservation policy on the EU fishing fleet:

"Fishing effort limits are an essential part of the multi-annual management plans… and will gradually become the prime management instrument for mixed fisheries. They will in general require a reduction in the activity of the existing fleet. Scientific advice currently recommends reduction in fishing effort of up to 60 per cent in several important Community fisheries. Where effort limits are part of a multi-annual management plan which foresees a significant reduction in fishing mortality, the reduction in activity will also be large(9). This will have obvious repercussions for fleet capacity." (section 3.2)

(9) In the case of the recovery plans for cod and hake, for example, the average reduction in fishing effort for the fleets concerned is 43% (COM(2001) 724 final of 11.12.2001).

This is aspect of the Commission's proposals has a significant bearing on the potential for across-the-board reductions of bycatch and discards.

The Commission concludes that: "The CFP has reached a turning-point. The challenges are urgent and serious. The current poor sustainability performance of the CFP proves that many of the instruments applied over the last twenty years have reached their limits. In this state of crisis there is a need for major change. Reform of the objectives, principles, priorities and instruments of the CFP is more than ever necessary to deliver sustainable development and to ensure that the European fishing industry has a secure future."

The Commission proposes that the "Council Regulation on the conservation and sustainable exploitation of fisheries resources under the CFP, establishing the framework within which conservation measures, measures to adjust fishing capacity and control and enforcement measures may be taken under the CFP" should enter into force by 1 January 2003.

Action Plan to integrate environmental protection requirements
The Action Plan to integrate environmental protection requirements into the CFP (European Commission 2002c) states that management action should give the highest priority to, among other things:

• within the framework of multi-annual management plans, a reduction in fishing pressure on fishing grounds to sustainable levels; where possible, and on the basis of scientific advice, this reduction should target fishing activities having adverse effects both on the sustainability of fish stocks and on the favourable conservation status of non-commercial species and habitats;
  
  
• an improvement of fishing methods with a view to reducing discards, incidental bycatch and impact on habitats. In the coming months, the Commission shall devise an Action Plan on discards and appropriate proposals to protect sharks, cetaceans and sea birds from adverse effects of fishing.

In order to reinforce the process of integration and accelerate its implementation, the following actions, among others, should be undertaken:

• the Commission will extend management measures to the protection of non-commercial species and habitats from the effects of fishing and aquaculture activities, and study the operational requirements of a full application of the precautionary principle to all aspects of the CFP implying environmental risks;

The Commission will consider whether a revision of the actions, targets and deadlines set out above is necessary, and report on this in 2005.

Footnotes

1. Quoted in OSPAR QSR 2000.

2. OSPAR (2000) states that fishing effort has dropped sharply since, and bycatch rates are also likely to have declined.

3. Also the pelagic fisheries for mackerel (Scomber scrombrus) and herring (Clupea harengus).

4. i.e. for every tonne of fish landed, 0.047 tonnes were discarded.

5. Trawl gear has been observed to penetrate up to 6cm into bottom sediments, and otter boards, used to hold open the net mouth, up to 30cm.

6. Some unobserved mortalities are generated, directly and indirectly, by interaction with the fishing gear. For example, the crushing or damage to scallops in the seabed incidental to the scallop trawl operations in the Bass Strait in Australia eliminated an entire scallop stock within nine months as a result of infection due to the decomposition of the crushed or damaged scallops. Other such mortalities result from the gear redistributing benthic species, so exposing them to increased predation.

7. ICES website: New approach to fish stock assessment.

8. A number of derogations from the main mesh size regulations are allowed, subject to restrictions on the use that can be made of the reduced mesh size. These restrictions are sometimes in the form of limitation on the minimum percentage of target species that may be caught. They may also specify a maximum limit on the percentage of the catch that can be formed of non-target species. Other derogations may be in the form of limitations on the area fished (Alverson et al. 1994).

References

Alverson D.L., Freeberg M.H., Pope J.G., Murawski S.A. 1994. A global assessment of fisheries bycatch and discards. FAO Fisheries Technical Paper. No 339. FAO, Rome. 233pp.

Berrow S.D., O'Neill M. and Brogan D. 1998. Discarding practices and marine mammal by-catch in the Celtic Sea herring fishery. Biology and Environment: Proceedings of the Royal Irish Academy 98B (1), 1-8.

European Commission. 2001. Green Paper on the future of the Common Fisheries Policy. COM(2001)135 final. Brussels, 20/3/01.

European Commission. 2002a. Preparation of the Council of Agriculture/Fisheries September 2002. Press Release 20/9/02.

European Commission. 2002b. Communication from the Commission on the reform of the Common Fisheries Policy ("Roadmap"). COM(2002)181 final. Brussels, 28/5/02.

European Commission. 2002c. Communication from the Commission setting out a Community Action Plan to integrate environmental protection requirements into the Common Fisheries Policy. COM(2002)186 final. Brussels, 28/502.

FAO. 1996. Fisheries Bycatch and Discards. COFI/97/Inf.7, December 1996. FAO Committee on Fisheries. Twenty-second session. Rome, Italy, 17-20 March 1997.

ICES. 2002. The 2002 Report of the Working Group on Marine Mammal Population Dynamics and Habitats (WGMMPH). ICES CM 2002/ACE:02.

NRC. 1990. The nature and scope of fishery dependent mortalities in the commercial fisheries of the Northeast Pacific. Natural Resources Consultants, Seattle, Washington, USA.

OSPAR. 2000. Quality Status Report 2000. OSPAR Commission for the protection of the Marine Environment of the North-East Atlantic. London.

Spencer N., Santos Vázquez M. B. and Pierce G. J. 2000. Evaluation of the state of knowledge concerning by-catches of cetaceans. Final Report to the European Commission (No. XIV/1999/01) (31/12/99 - 31/10/00). Department of Zoology, University of Aberdeen, AB24 2TZ, Scotland.

Please note: This page will be updated during 2006.