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FAO Fisheries Circular No. 920 FIRM/C920

Rome, 1997

ISSN 0429-9329

Marine Resources Service,
Fishery Resources Division,
Fisheries Department,
FAO, Rome, Italy


FAO Statistical Area 27



The North Atlantic features a large subpolar gyre that plays a central role in the distribution and ecology of fish stocks in the Northeast Atlantic area (Figure B2.1). The presence of this subpolar gyre was illustrated by the "Great Salinity Anomaly", when a huge volume of cold, low salinity water travelled around the gyre from 1968 to 1981. Fish stocks in its path experienced poor recruitment, possibly due to reduced food supply and the colder temperature of the anomalous delayed primary production blooms. Other oceanographic features of the Northeast Atlantic include the extended shelf area off Northern Europe, the semi-enclosed Baltic Sea, and summer upwellings off the coast of Spain and Portugal.

Most of the traditional fishery resources of the Northeast Atlantic are fully or overexploited, with several stocks in a depleted condition. The collapse of the North Sea herring stock for the second time in the last twenty years, and the resulting advise of 50% reduction in fishing mortality, has received much attention, although reductions of up to 40% have been advised for other stocks. The root cause of this poor situation within European waters has been the inability of the member states within the European Union (EU) to control and reduce fleet capacity within the Common Fisheries Policy. The EU Commission called for cuts of up to 40% in the size of certain fleets to be included as part of the Fourth Multi-Annual Guidance Programme (that is scheduled to run from 1997 to 2002).


Figure B2.2
figure The fisheries of the Northeast Atlantic expanded rapidly in the late 19th and early 20th century as fishing became mechanized, with short periods of relative inactivity during World Wars I and II. This expansion continued throughout the 1950s and 1960s peaking in the mid-1970s at over 13 million tonnes; since catches have declined to an average of approximately 10 million tonnes during the late 1980s and early 1990s (Figure B2.2 and Table II). The pattern of total catches masks the fact that during this period (1950 to 1994) the share of the total catch made-up by historically valuable or traditional species such as North Atlantic cod, haddock and herring has declined, while catches of many formerly lower-valued species (such as sandeels and blue whiting) have increased.

Figure B2.3 Figure B2.4
figure figure Catches of Atlantic cod have consistently made the largest contribution to the total catch of ISSCAAP Group 32 species (Figure B2.3), although a persistent downward trend had been evident since the peak catches of the late 1960s. The later development of the blue whiting fishery delayed peak catches of this species until the late 1970s, after which a downward trend is also evident. The behaviour of the total pan-Northeast Atlantic catches of other species of ISSCAAP Group 32 has been similar, peaking in the early 1970s and then declining (Figure B2.4).

Figure B2.5

Catches of the pelagic species of ISSCAAP Groups 34, 35 and 37 are shown in Figure B2.5. Catches of Atlantic herring and capelin have shown greater short-term variability than catches of many other species, including other pelagics. This is partly due to the greater dominance of fewer stocks. For instance, the sharp decline in Atlantic herring catches around 1967-68 was caused by the collapse of the Norwegian spring-spawning herring fishery, while the low level of catches from 1974 to 1984 was caused by a decline in the North Sea herring stock (which was closed in 1977 for 4 years). Similarly, the decline in capelin catches in the mid-1980s was due to the collapse of the Barents Sea capelin fishery, which was closed from 1986 to 1991.

Figure B2.6
figure The small-mesh fishery for sandeels (in ISSCAAP Group 33) has expanded dramatically since the late 1960s but there has been no persistent trend in catches since the mid-1980s (Figure B2.6). The other ISSCAAP Group 33 species for which significant catches are taken are the Atlantic redfishes (various deep-sea and oceanic stocks of Sebastes mentella and S. marinus). Catches of shrimps (ISSCAAP Group 45) have increased since the early 1980s. This increase has come predominantly from catches of northern prawn: the combined catches of other ISSCAAP Group 45 species has declined slowly since the mid-1950s.


The origins of modern fisheries stock assessment and management science can be traced as far back as late 19th Century studies of North Sea fisheries. The International Council for the Exploration of the Sea (ICES, founded in 1902) provides assessments and/or management advice for over 100 stocks or sub-stocks in the Northeast Atlantic. The majority of these stocks (approximately 70) are analyzed each year by various ICES Working Groups using age structured stock assessments. The quality of the stock assessments varies and several are considered unreliable because of, either singly or in combination: unreliable or insufficient catch-at-age data; unreliable commercial catch data, particularly in recent years, due to mis-reporting; uncertainty over stock identity; conflicting trends in CPUE series and/or an absence of collaborative data from fishery independent sources. The status of the main resources and stocks is reviewed below.

Northeast Arctic Fisheries (ICES Sub-areas I and II)

Following the near collapse of the Northeast Arctic cod stock in 1988-89 the USSR/Norwegian joint commission agreed a reduction in TAC of over 50% in the offshore fishery for 1990 and 1991. This TAC was well enforced and the reduction in fishing mortality (F), together with a good 1983 year class and improved growth and survival due to abundant prey (capelin - see below), resulted in the rapid recovery of the stock biomass. The stock is currently considered to be within safe biological limits, although F has nearly doubled since 1990 and is now above Fmed (0.46). There are concerns that poor growth and increased cannibalism due to the depleted capelin biomass may require F to be reduced from the current level to ensure the stock remains within safe biological limits in the medium term. However, a possible alternative food source, the Norwegian spring spawning herring (see below), is in good condition.

Catches of haddock and saithe are typically an order of magnitude lower than those of cod, and the stocks of both species are considered to be within safe biological limits. Both the stocks of the redfish Sebastes mentella and Greenland halibut are below safe biological limits. Redfish catches may have to reduced to the minimum possible for spawning stock biomass (SSB) to increase, while the ACFM recommended that the Greenland halibut fishery be closed in 1996.

The Norwegian spring-spawning herring fishery collapsed in the late 1960s owing to a recruitment failure following the fishing down of the SSB to below 2.5 million tonnes. The SSB remained low until the mid-1980s and virtually no fishing took place on the stock for 15 years. Since the mid-1980s the SSB has increased and in 1994 catches were taken in offshore areas of the Norwegian Sea for the first time in 26 years. Strong year classes are expected to recruit in 1996-1998 and in the short term the stock size is increasing. However, the highly variable recruitment and vulnerability of the stock to collapse means that no long-term gains are expected by increasing fishing mortality above the level of 1995. In order to prevent SSB falling below the minimum biological acceptable level (MBAL), the Advisory Commitee for fisheries Management (ACFM) has suggested that management using limitations on both fishing mortality and total catch is required.

The Barents Sea capelin fishery collapsed for the first time in 1985 and was closed from 1986 to 1991. By 1991 the SSB had recovered to ~1.8 million tonnes - above the levels of the 1970s - and fishing recommenced. However, by 1993 SSB had again collapsed and the fishery was closed. The SSB remains well below safe biological limits and recruitment has been poor since 1992. While the short life span of the species is a key factor in the size of the short-term variation in SSB, the fate of the capelin stock is closely tied to that of its main predator, Northeast Arctic cod. As described above, the Northeast Arctic cod stock was at very low levels in the late 1980s, but has since rallied, resulting in high predation pressure on the capelin. The year classes that will form the majority of the capelin stock for the next 3 years are very weak, and it is unlikely that a fishery will restart before 1999.

The Baltic (ICES Divisions IIIb-d)

The major part of the Baltic is distinct from the rest of the Northeast Atlantic, although there are linkages between the Southwestern Baltic and the Kattegat. The conditions for fish populations in the Baltic are entirely dependent on inflows of oceanic water from the North Sea, with salinity and oxygen availability being high immediately following an inflow and steadily decreasing afterwards. These inflows are irregular, infrequent and vary in strength. Large inflows occurred in 1970, 1974, 1976 and 1979, with a prolonged stagnant period throughout the 1980s before a medium sized inflow in 1993.

Recruitment to the Eastern Baltic cod stock is poor during stagnant periods. The strong year classes associated with good environmental conditions in the late 1970s lead to SSB peaking in 1982 (~1 000 000 t) before declining steadily until reaching a low of ~175 000 t in 1992. Improved efficiency due to changes in gear and increases in fleet size led to fishing mortality (F) exceeding 1.0 by 1986. Agreed TACs (first set in 1989) have consistently exceeded those advised by ICES and have in turn consistently been exceeded by actual catch levels. Where ICES advised no fishing at all in 1993, the TAC was set at 40 000 t and actual catches were estimated to be ~100 000 t. The extent of unreported landings since 1992 has been large, and serious problems exist in enforcing regulations. Concerns over future recruitment and rebuilding of the SSB led ACFM to recommend a further 20% reduction in F for 1997 relative to the 1995 level. Both the Kattegat and Southwestern Baltic cod stocks are believed to be rebuilding since historically low levels in 1991 and 1992 respectively.

Herring recruitment and SSB are very high for the Gulf of Riga, Bothnian Sea and Bothnian Bay stocks. In contrast, recruitment to the major stock of the Eastern Baltic has been below the 1974-1994 average since the mid 1980s and the SSB reached a historic low in 1991 from which it has not recovered. However, fishing mortality is around F0.1 and the stock is considered within safe biological limits.

An assessment of the Eastern and Southwestern Baltic sprat stock shows the SSB reached record levels in 1993-94. The stock is within safe biological limits and catches could be increased substantially. However, sprat, together with herring, is a major prey item for cod in the Baltic and thus natural mortality may be expected to increase with cod abundance.

The North Sea, Skagerrak and Kattegat, and Eastern Channel (ICES Sub-area IV, and Divisions IIIa and VIId respectively)

The main cod stock is the North Sea stock, with both the Skagerrak and Eastern Channel stocks thought to be sub-components. The North Sea cod stock is well outside safe biological limits, with the SSB of 1994 only 3% higher than the historic record low of 1993 and 62% lower than MBAL. The SSB has declined almost monotonically since the peak in 1968, despite the strong year classes of 1969, 1970, 1976 and 1979 (part of the so called "gadoid outburst"), and fishing mortality (F) has fluctuated around ~0.9 since the early 1980s (above Fmed of 0.81). In the last decade only 2 recruiting year classes have been above average. Following advice in 1991-1993 to cut F directly by 30% relative to 1989, and a "significant reduction" in 1994 and 1995, ACFM has advised for 1996 a cut of 20% relative to 1994. Despite this advice the agreed TAC remained at ~100 000 t from 1991 to 1994 before climbing to 120 000 t in 1995.

The main stocks of haddock and whiting (caught as part of a mixed groundfish fishery with cod) are in the North Sea, with much smaller stocks in the Skagerrak, Kattegat and Eastern Channel. The North Sea haddock stock has improved since the record low SSB of 1991 and, although fishing mortality (F) continues to be high (above Fmed), the stock is considered to be within safe biological limits. However, if stock size remains at current levels, catches of haddock will continue to be highly variable, depending largely on the strength of individual recruiting year classes. The status of whiting is uncertain due to conflicting trends within the assessment, although it is thought to be within safe biological limits. A separate fishery for saithe throughout the area started in the early 1970s and SSB declined to a historic low in 1990. Assessments indicate there has since been a 25% increase to 1994 and the stock is currently considered to be close to safe biological limits.

The other main demersal species in the area are the flatfish, with the main stocks being in the North Sea. North Sea plaice and sole are the major components of the mixed flatfish fishery. A persistent and rapid decline in SSB in the plaice stock since 1989 resulted in a historic record low in 1994. This decline occurred despite the fact that actual landings and fishing mortality (F) appear to have been smaller than those advised by ACFM since 1989. The stock decline may have been unavoidable (agreed TACs were set higher than advised, and may have been set at such levels regardless of ACFM advice), but ACFM was aware that the stock assessments between 1991 and 1993 were unreliable. The current stock assessment is considered more reliable and, with SSB below MBAL, the ACFM has advised a 40% reduction in F as the minimum requirement to achieve a high probability of recovery above MBAL in the medium term.

After 25 years of average or below average recruitment of North Sea sole, the very strong year classes in 1987 and 1991 have rebuilt the SSB to the highest levels since the 1960s and the stock is considered within safe limits. Both the smaller stocks of sole and plaice in the Eastern Channel are considered within safe biological limits.

The main stocks of sandeels and Norway pout targeted by the small-mesh fishery are found in the North Sea. The North Sea Norway pout stock is considered within safe biological limits, but high bycatches of juveniles of other demersal species, particularly whiting, remain a concern. The North Sea sandeel stock is considered within safe biological limits, with little bycatch of protected species. The fishery on the smaller Shetland stock, closed completely in 1991 following seasonal closures in 1989 and 1990, was re-opened in 1995 after the recruitment of a strong 1991 year class. A multi-annual (3 year) TAC of 3 000 t is set for the stock, which is considered to have recovered above safe biological limits.

Several stocks of shrimp exist throughout the North Sea and Skagerrak. The short-lived nature of Pandalus spp in the North Sea means stock status is largely dependent on the recruiting year class. Catches fluctuate widely due either to varying fishing effort as market prices change or changes in stock levels. Recent recruitment to the Skagerrak and Norwegian Deeps shrimp stock has been at average levels, with SSB above average due to a strong 1992 year class.

The status of the North Sea herring stock is catastrophic. The resource status has not been so poor since the virtual commercial extinction of the stock in the 1970s resulted in the closure of the fishery from 1977 to 1981. A modest recovery in the early 1980s resulted in SSB levels climbing briefly above MBAL (800 000 t) from 1987 (the first time this had been true since 1968) to 1992. While the agreed TAC was within the advised TAC from 1987 to 1992 inclusive, actual catches were typically 40% higher. In 1993 ICES advised a reduction in TAC but the agreed TAC was not changed, and actual catches dropped by less than 5%, with the result that actual catches exceeded advised levels by over 50%. The advised and agreed TACs in 1994 remained essentially unchanged from 1993, while actual catch dropped by a further 10%. The advised fishing mortality (F) for 1995 corresponded to a TAC that was actually 24% higher than that for 1994 (due to an overly optimistic assessment) despite SSB levels below MBAL. The 1996 TAC advised by ICES is 298 000 t, with the added recommendation that F be further reduced in 1997, possibly to zero if the 1996 TAC is exceeded. If it were not for recent recruitment being at average levels, it is probable that ICES would have advised that the fishery be closed this year. Given the variability in recruitment to this stock it is clear that if F is not reduced and SSB is not rebuilt rapidly, the probability that another prolonged period of effective commercial extinction may occur is high.

Iceland, the Faeroe Islands and the Irminger Sea / Greenland (ICES Divisions Va and Vb, and Sub-areas XII and XIV respectively)

The fishery in the Faeroe area is multi-fleet and multi-species. An ITQ-based management system was introduced in 1994 but was deemed a failure, with substantial increases in discarding and misreporting, and a new management system based on individual transferable (within same-gear categories only) effort quotas started in June 1996. The SSB of the Faeroe plateau cod stock was well below MBAL from 1989 to 1993 but has been at, or slightly above, this level for 1994 and 1995. Fishing mortality (F) levels in 1993-94 were the lowest since the 1970s, although not as low as wanted by the ACFM (which advised no fishing at all), and climbed above Fmed again in 1995. ACFM recommended that F be at the "lowest possible level" in 1996, although the agreed TAC has actually increased by 60%.

A similarly discouraging situation exists for haddock, with the agreed TAC being over 50% higher than that advised by ACFM, despite SSBs around 50% below MBAL since 1991. However, in both cases good recruitment is expected to result in increases in SSB, at least in the short term. The situation for saithe, with SSB at record low levels, is worse, and ACFM advises a 20% reduction in F and a low TAC.

Icelandic demersal fisheries (excluding oceanic redfish) have been managed by an ITQ based system since 1984. The SSB of the Icelandic cod has been at low levels since a slight increase following the increases in mesh size after the adoption of extended fisheries jurisdiction (EFJ) in 1975. Actual catch levels have exceeded those set by the Icelandic government for the past decade and fishing mortality (F) has been correspondingly high. In 1993 recommended TAC levels were set 40% lower, and by 1995 the agreed TAC and actual catch were both around 40% lower than in 1992, resulting in F in 1995 being the lowest since the late 1970s. A formal harvesting strategy whereby TAC is set at 25% of available (> age 4) biomass was introduced in 1995. This strategy is consistent with ACFM advice (although the assessment is uncertain due to difficulties in measuring maturity at age) and is likely to allow rebuilding of the stock. The Icelandic saithe stock is considered within safe biological limits, and the agreed TAC has not been restrictive since 1993, partly due to constraints imposed by the strict TACs introduced in the cod fishery.

All the cod stocks around Greenland remain almost non-existent, and ICES recommends that no fishing should take place. The other main northwestern demersal resources are Greenland halibut and redfish. Each year since 1992 the F on Greenland halibut has reached a new historic high level, and SSB is now close to a record low. There is considerable uncertainty in the estimate of SSB, and fishing mortality (F) is thought to be underestimated. ACFM has recommended a cut of 60% in F from 1995 levels. The redfish resource is made up of two species, Sebastes marinus and S. mentella, with S. marinus supporting a shelf fishery down to 500m while S. mentella supports both a pelagic oceanic fishery and a deep-sea fishery in the Irminger Sea (0 to 500m, and below 500m respectively). The ranges of the three stocks differ, and different fisheries exist on different parts of the ranges. The catches of oceanic S. mentella in ICES Sub-areas XII and XIV are almost all taken in international waters, although the same stock is found, at least at certain times, within the EEZs of Greenland and Iceland. Both the S. marinus and deep sea S. mentella stocks are thought to be at very low levels, and ICES advises a cut in F of 25% from the 1995 levels. There is great uncertainty over the status of the oceanic S. mentella stock. This uncertainty prevented ICES giving any catch advice although the possibility that recruitment could fail for several years before being observed is of concern.

The Iceland summer-spawning herring stock SSB is currently at a historically high level. Following the collapse of the stock in 1968 a ban on fishing was enforced from 1972 to 1975 and, with fishing mortality (F) levels low since then (around F0.1), the SSB has increased nearly continuously since 1971. Recruitment has also been increasing and the stock is healthy, although increasing F will not provide long term increases in yield. Good recruitment has lead the capelin stock SSB to recover very quickly from the unsafe low level of 1990 and it is now at a record high, although there is considerable uncertainty in the assessment which is based on acoustic surveys. There is concern that F on juveniles should be minimised, possibly via seasonally closed areas.

The West of Scotland and Rockall, the Irish and Celtic Seas, and the Bay of Biscay (ICES Divisions VIa-b, VIIa-c and VII e-k, and VIIIa-b respectively)

The cod stocks of the West of Scotland, Rockall, Irish Sea and Celtic Sea are all considered to be outside safe biological limits to varying degrees, and ACFM advises reductions in fishing mortality (F). The saithe stock (West of Scotland and Rockall) is considered outside safe biological limits, with SSB still close to the record low level of 1992. F is estimated to have dropped sharply in recent years (although the figures are uncertain) and ACFM advises that low levels be maintained.

Catches of Irish Sea plaice have generally been below advised TACs since 1988, but the SSB declined below average levels in 1990 and has yet to recover significantly. However, these historically low levels of SSB do not appear to be sufficiently low to reduce recruitment and the stock is considered close to safe biological limits. However, similarly historically low levels of SSB of Irish Sea sole are associated with poor recruitment and a 20% reduction in fishing mortality (F) is advised. The Celtic Sea plaice and sole stocks are considered to be near safe biological limits and a 20% reduction in F is advised. Low levels of SSB for plaice in the Western Channel has lead ACFM to advise a 60% reduction in F. Since TACs for plaice in the Western and Eastern Channel are combined and the Eastern Channel stock is much larger, a direct reduction in F rather than TAC is necessary. Western Channel sole are also close to biologically safe limits and ACFM calls for a reduction in F. The fisheries for different species of anglerfishes towards the south are managed together and ACFM advises no increases in F.

There are several herring stocks in the area, all of which are small relative to the main North Sea stock. The spawning biomasses of all these stocks appear to have been at low levels in the 1970s. While most of the stocks have increased almost continuously since (VIa, VIIa,j), the SSB for the stock in VIa (South) and VIIb-c has decreased since the late1980s. The level of uncertainty associated with the assessments of these stocks is generally high.

Iberian Region (ICES Division VIIIc and Sub-areas IX and X)

Hake is the major demersal resource of the Iberian region, together with anglerfish and megrim. The SSB of hake in 1994 was at a record low and ACFM advises that fishing mortality (F) be kept at the lowest possible level, preferably zero, in order to allow spawning biomass to rebuild. The main stocks of megrim (taken as bycatch in the hake fishery) and anglerfishes are thought to be at low levels. The Southern horse mackerel stock appears stable, but the sardine stock is at low levels and ACFM advises that catches should be reduced as much as possible. A change in catch composition towards juvenile anchovy in the anchovy fishery suggests that spawning biomass is low. ACFM suggests that a seasonal closure to protect juveniles could increase SSB and safeguard recruitment without causing significant reductions in catch.

North Atlantic and Baltic Salmon Stocks

There are over 1000 salmon rivers in the North Atlantic Salmon Conservation Organization's (NASCO) North-east Atlantic Commission (NEAC) Area, and MBALs have been established for only seven. These monitored rivers suggest that there is no trend in smolt production in the Northeast Atlantic as a whole. Stocks in the main basin of the Baltic are in better condition than those in the Gulfs of Bothnia and Finland in the Baltic, which are severely depleted. Less than 50% of the original stocks still exist, and catches are only sustained by reared salmon (which make up over 90% of the catches). All stocks have been badly affected since 1992 by the M74 syndrome, a condition which causes high mortality in newly-hatched yolk-sac fry from sea-run females. The cause(s) of this disease is still under investigation, although thiamine deficiency resulting from consuming prey with high thiaminase activities is gaining credence over theories regarding organochlorine contamination.

Widely Distributed, Deep-Water and Migratory Stocks

Blue whiting are caught from the Barents Sea to the Straits of Gibraltar and, although absolute population estimates are imprecise, the stock does appear to have been relatively constant since the early 1980s. Mackerel, now assessed as a single stock, may be outside safe biological limits and ACFM advises a significant reduction in fishing mortality (F). The western horse mackerel stock is within safe biological limits. Northern hake are found from the Bay of Biscay to the Celtic, Irish and North Seas. The stock is considered to be outside safe biological limits and ACFM advises a 30% reduction in F and improved enforcement of mesh size and minimum landing size regulations.

Deep-water species such as the argentine or greater silver smelt, roundnose grenadier and Atlantic orange roughy, along with many other species of fish (>20) and sharks (>10), are now caught in deep-water fisheries. The long life-span and associated low rate of increase of many of these species means that catches can be sustained for a number of years as the stocks are "mined" before suddenly collapsing. ICES has advised a precautionary approach where effort is kept as low as possible while understanding about the response of these species to fishing is improved. A first step in gaining such an understanding is identifying the most important components of the catch at the species level and reporting their catches.

Environmental Issues

Trawling with heavy gears is thought to have a major impact on the sea bottom, altering and degrading marine habitats and possibly causing loss of species diversity. Demonstrating statistically significant causal links between sea bottom degradation and fish production will be difficult, even if such links may exist, but a comprehensive impact assessment has not been carried out. Concern has been expressed over possible damage to the spawning grounds of Celtic Sea herring caused by gravel extraction along the Irish coast. Other environmental concerns arise out of the growth of mariculture and sea ranching and potential impacts on wild population genetic make-up (e.g. Baltic salmon).

Management Issues

The above review of the commercial fish resources of the Northeast Atlantic reveals that the majority of the resources are fully or overexploited, with several stocks in a depleted condition. This situation has been brought about largely by long-term overfishing, although environmental factors may have played a significant role in a few stocks. The review highlights the fact that catches often exceed agreed TACs, that agreed TACs often exceed those advised by ICES, and that advised TACs have been based on uncertain, and often optimistic stock assessments.

The large overcapacity of the European fleet and the poor status of many of the resources has led to agreed TACs being restrictive for an increasing number of stocks. The difficulties inherent in enforcing output based fisheries regulations such as TACs (rather than input based measures such as limited entry) and the resulting low probability of detecting transgressions creates economic conditions that encourage illegal overfishing. Hence, actual catches exceed restrictive agreed TACs. In an effort to improve this situation, the EU Commission called for cuts of up to 40% in the size of certain fleets to be included as part of the Fourth Multi-Annual Guidance Programme (scheduled to run from 1997 to 2002).

The agreed TAC of a given stock can also be exceeded because fish from the stock are taken as bycatch in fisheries targeting other species. This bycatch can be landed as illegal over-quota fish or can be discarded at sea in conformity with the current legal requirement. Discarding is a significant factor in the Northeast Atlantic fisheries, and in part appears to be a consequence of setting quotas on individual species in what are mixed species fisheries. This encourages high grading and discarding that some estimates put as high as 50% of the demersal catch by weight, although the general absence of observers on commercial vessels makes quantification difficult. Some countries have started sampling programmes where observers sample discards on a haul-by-haul basis.

Illegal catches are either not reported at all or are reported as different under-quota species, resulting in a deterioration in the quality of fisheries statistics used for stock assessments. This situation is worsening and is a cause for great concern. The ACFM has warned that, if data quality continues to deteriorate, it will become impossible to monitor certain stocks, particularly with regards to the provision of short-term forecasts used for setting TACs. The under-reporting of catches, particularly where the level of under-reporting is unknown and/or fluctuates widely, can result in the under-estimation of stock size, which, in turn, results in larger discrepancies between actual and predicted catch rates. As this discrepancy grows, the incentive for fishers to continue fishing illegally increases and the degree of under-reporting of catches increases. This combination of high exploitation intensities and poor quality data has lead to concerns over the future effectiveness of TAC-based quota management. For instance, the ACFM suggests that stand-alone technical measures or catch controls are likely to be insufficient in reducing fishing mortality on the Irish Sea cod stock such that spawning stock biomass can return to safe biological levels.

There is currently considerable research effort going into the reduction of bias and uncertainty in stock assessments and improving the way in which these factors are communicated to decision makers. For instance, predator-prey interactions that lead to variability in certain stock parameters (e.g. natural mortality and growth) have been investigated using multi-species virtual population analyses (MSVPA) based on data collected by large-scale stomach sampling programmes. Additionally, the problems with commercial data highlighted above have led to increasing use of research vessel survey data in estimating current stock sizes.

However, it is clear that better assessments are not sufficient for improved management. In addition to the illegal over-quota fishing problems noted previously, the pattern of agreed TACs exceeding advised TACs continues. The form of advice being given by ACFM has improved over the past decade and the problem of agreed TACs exceeding advised TACs cannot be attributed solely to poor understanding of this biologically based scientific advice on the part of fisheries administrators. In European waters, the EU Council is required to take into account economic and social conditions as well as resource status when agreeing on TACs. The implications on stock status of considering increased catches based on these factors remains uncertain but is of concern.

The above review highlights the fact that many past decisions on the setting of TACs (and/or levels of fishing effort) appear inappropriate in light of the biologically based advice. The pattern of agreed TACs exceeding advised TACs has contributed, together with the enforcement problems and stock assessment uncertainties discussed above, to the poor long-term performance of TACs as management measures. In contrast, effective management of fishing fleets with reduced capacity could provide many benefits, including increased overall landings and economic yields, increased profitability and increased stability in catches, while reducing the risk of stock collapse.