The global hunt for fish
The art of counting fishNo other group of animals is as difficult to monitor as fish. Spotting scopes and radar equipment are used to locate and count migratory birds along their flight paths. Bats can be monitored by placing ultrasound detectors and photoelectric sensors at the entrance of their caves. But what about fish? Humans are not capable of looking into the ocean and counting the fish they see. Instead, they must try to estimate the size of fish stocks as accurately as possible. The Food and Agriculture Organization of the United Nations (FAO) uses various sources to estimate global fish stocks and trends as accurately as possible. The results are published every two years in the SOFIA Report (The State of World Fisheries and Aquaculture). The latest report was released in 2012 and reflects the developments to 2009/2010. Fish is the means of subsistence for billions of people around the world. Accordingly, the report is an important document on which UN decisions, international agreements and treaties are based. The data used for the SOFIA Report is taken from the following sources: FISHERIES – Fishermen report their catches to their government authorities, such as the Ministries of Agriculture and Fisheries. The authorities are obliged to send this data to the FAO. The data is also forwarded to scientists in their own country. THE SCIENTIFIC COMMUNITY – Fisheries’ data is of-ten incomplete or incorrect. For instance, fishermen only report the amounts of those fish which they are officially permitted to catch. They do not include any unwanted “bycatch” – all the fish and marine fauna which are caught inadvertently and until now have mostly been thrown back overboard. An quantitative assessment of bycatch levels would, however, be crucial as this could provide a more realistic estimate of the actual status of fish stocks. In order to improve the flawed basic data, fishery scientists therefore gather their own data. 1. Fishery-dependent data: Fishery scientists regularly accompany fishing vessels. They collect catch samples and detailed data including the age, size, length and number of adult fish. The volume and composition of the catch are of particular interest. They also record the effort expended, such as how long a net is dragged behind the vessel before it is full. This establishes the exact amount of effort involved in catching a certain amount of fish. Researchers call this the “catch per unit effort” (CPUE). It is the only way of ascertaining the stock density, or the number of fish found in a certain area. 2. Fishery-independent data: Scientists also conduct research projects using their own vessels. They take nu-merous sample catches – not only in the abundant areas highly sought after by the fishermen, but in many different parts of a maritime region. The sampling locations are either chosen randomly or according to a certain pattern. The objective is to obtain a comprehensive overview of the entire maritime region as well as the distribution of fish stocks. During these expeditions it is important that all the marine fauna caught are counted and measured, to enable a reliable assessment of the entire ecosystem to be made. The scientists are also interested in the age of the fish. Using close-meshed nets, therefore, they catch young fish (juveniles) which are not usually taken by the fishermen. The age distribution of the fish is an extremely important aspect of stock predictions. It shows how many of the fish will grow to sexual maturity and thus how populations are likely to develop in future years. How many research expeditions are undertaken differs from country to country. Researchers sample individual fish stocks up to five times a year. Information on the eggs and larvae of some stocks is also recorded. These numbers indicate the parent stock and the numbers of young to be anticipated. The researchers utilize both the fishery-dependent and the fishery-independent data to adjust and augment the fisheries’ official catch numbers. For instance, from their own sample catches they can estimate the approximate volume of bycatch in the fishing grounds. In many cases catches from illegal fishing are also shown up. For instance, double logbooks are frequently used – one for the authorities showing the official figures, and another for the scientists showing the higher but genuine catch numbers. Comparing these two allows a more accurate estimation of how many fish were actually caught in a maritime region.
- 3.1 > Venerable gentlemen of fisheries science: ICES researchers held their statutory meeting at the House of Lords in London in 1929. Upon its foundation in 1902, the ICES had 8 member nations: today it has 20.
The International Council for the Exploration of the Sea (ICES) was founded in Copenhagen, Denmark, in 1902 and is the world’s oldest intergovernmental organization. At that time there was a growing awareness in some European fishing nations that the long-term management of migratory fish stocks depended on a coordinated approach. Today the ICES acts on behalf of the EU and other fishing nations such as Canada, Iceland and Russia. It is responsible for all the living marine resources in the Northeast Atlantic, a total of 120 species. The ICES recommends the maximum fish catches within a specific maritime region.
How does the data reach the FAO?The catch data from both the fishermen and the scientists is initially forwarded to higher scientific institutions which utilize it to estimate the current stocks of the various fish species and maritime regions. One objective is to generate a supra-regional overview from the national data. For example, the International Council for the Exploration of the Sea (ICES) in Copenhagen is responsible for the Northeast Atlantic. Its working groups use both the fisheries’ official catch data and the scientific results to calculate the current stocks of the different species of fish and fauna. The ICES then sends these stock estimates to the FAO.
Data about stocks in other maritime regions reaches the FAO in a similar way. For example, the Northwest Atlantic Fisheries Organization (NAFO) is responsible for the Northwest Atlantic. It collates data from Canada, the USA, France (for the Atlantic islands of St. Pierre and Miquelon) and the foreign fleets from Russia and the EU which operate in this region. The NAFO then forwards the data to the FAO. The Canadian and US national fisheries institutes also report directly to the FAO.
The FAO does not re-evaluate this information, but merely summarizes, edits and ultimately publishes the data for the various maritime regions of the world.
Disagreement on the condition of fish stocksAround 1500 fish stocks around the world are commercially fished, with the various stocks being exploited to different extents. Comprehensive estimations of abundance currently exist for only around 500 of these stocks. In most cases these are the stocks which have been commercially fished for many decades. For many years, exact records have been kept of what and how much is caught: the tonnages and also the age and size of the fish. Datasets for cod off the coast of Norway, for example, go back as far as the 1920s. Very little is known about other fish species and maritime regions – particularly the Exclusive Economic Zones of some developing countries. Many developing countries provide catch data alone, without any scientific assessment. The FAO makes limited use of such data. There are also some maritime regions for which not even simple catch data is available. The FAO believes that it is impossible to make any reliable estimation of such stocks.
Therefore no reliable data exists for many of the world’s fish stocks. Moreover, fisheries biologists are even unable to confirm how many fish stocks there actually are. If any data is available, it applies only to commercially exploited species. Naturally an overall survey of all the world’s fish would be desirable – but the cost would be exorbitant. Hundreds of research expeditions would be required, making the exercise unaffordable.
- 3.2 > Global estimation of fish abundance: Data on the status of fish stocks is provided by the fisheries and scientists. The FAO collates this information and then attempts to draw up a picture of the worldwide situation. The problem is that reliable data exists for only about 500 stocks. Experts do not agree on the status of other fish stocks.
- Critics point out, therefore, that the FAO statistics do not take a large proportion of stocks into account. A joint American-German research group has therefore developed its own mathematical model to estimate the status of all populations from the catch amounts reported by the fisheries alone, without the fishery-independent data from the scientists. These researchers are also investigating how stock catches have developed over time. According to this model, a fish stock is depleted when the catch decreases conspicuously within a few years. Attempts are being made to circumvent the lack of stock calculations by simply interpreting catches over the course of time. The researchers have meticulously requested information from the authorities of the countries responsible for regions with no catch data at all. Based on the model, which takes 1500 commercially exploited stocks and around 500 other stocks into account, the fish are in even worse shape than assumed by the FAO: 56.4 per cent of the stocks are overexploited or depleted, not 29.9 per cent as claimed by the FAO. But the work of this American-German research group is itself under fire, with claims that its data is inconsistent and still unreliable. It presents a distorted picture of the reality, say other researchers. Which of the methods better illustrates the state of the world’s fisheries is currently a subject of heated debate. Despite the uncertainties, the researchers and the FAO agree on one thing: over the years the situation has deteriorated. Recovery will only be possible if the endangered stocks are fished less intensely for a number of years.
Things are gradually getting worseThe results are alarming, because the pressure on fish populations has been escalating for years. According to the current SOFIA Report, the proportion of overexploited or depleted stocks has increased from 10 per cent in 1974 to 29.9 per cent in 2009. After temporary fluctuations, the proportion of fully exploited stocks rose during the same period of time, from 51 per cent to 57 per cent. The proportion of non-fully exploited stocks, in contrast, has declined since 1974 from almost 40 per cent to only 12.7 per cent in 2009.
A clear trend is therefore emerging: as far as overfishing and the intensive exploitation of the oceans are concerned, the situation is not improving; it is slowly but steadily deteriorating. It is interesting that the total annual fish catch has been fluctuating for about 20 years between a good 50 and 60 million tonnes. It peaked in 1994 at 63.3 million tonnes. In 2011 a total of 53.1 million tonnes was landed – about four times more than in 1950 (12.8 million tonnes). The FAO, however, records the catches of not only fish but also other marine species such as prawns, mussels and squid. If these numbers are added to those for fish, total catches are much greater. Accordingly, for the past 20 years the total marine catch has been a steady 80 million tonnes annually. The peak was reached in 1996 with 86.4 million tonnes. In 2011 it was 78.9 million tonnes.
Fig. left 3.3 > The number of overexploited stocks has soared since the 1970s, while the number of non-fully exploited stocks has decreased. Fully-exploited stocks are not, in principle, problematic. It is important to manage them sustainably, however.
Fig. right 3.4 > The development of catch volumes of world marine capture fisheries since 1950. Catches in China might have been adjusted upwards for many years, in order to comply with the government’s official output targets.
- The reason why fish catches have remained fairly stable is because over time the coastal maritime regions were fished out, prompting the fisheries to spread out into new areas. They have expanded in geographical terms, from the traditional fishing grounds of the North Atlantic and North Pacific further and further south. They have also penetrated into ever-deeper waters. Only a few decades ago it was virtually impossible in technical terms to drop nets deeper than 500 metres. Today the fisheries are operating at depths of up to 2000 metres. Moreover, once the stocks of the traditional species had been exhausted, the fishing industry turned to other species. Some of these were given new names in an effort to promote sales and make them more attractive to consumers. For instance the “slimehead” went on sale as “orange roughy”. It is still possible to remove virtually the same amounts of fish from the oceans, therefore, but the composition of the global catch and the stocks themselves have changed. Consistent catches are no indication that fish stocks have remained stable.
China catches the most fishTaking catch volumes as the benchmark, China has been the most important fishing nation for years now. However, the data available is extremely unreliable. A large number of experts believe that catches have been adjusted upwards for many years, in order to comply with the government’s official output targets. Therefore the figures have presumably been too high for some time. Only recently has this practice begun to change in China. Peru, until 2009 the second most important fishing nation, has slipped to fourth place. This is due to the low catches of anchovies which can be ascribed to climate change in particular, but also to a complete closure of the fishery designed to protect future anchovy stocks. Indonesia is currently the second and the USA the third most important fishing nation. Developments in Russia are interesting. Since 2004, its catches have increased by about 1 million tonnes. According to the Russian authorities, this growth is a result of changes to the comprehensive documentation of catches. Until now some local catches were registered in the home port as imports and not as domestic catches. Russia plans to further expand its fishing industry in the coming years, the goal being to land 6 million tonnes by the year 2020. This would amount to slightly more than the combined catches of all EU nations, which totalled 5.2 million tonnes in 2010.
A new way of thinkingThe situation is grave, but not without hope. The days of rampant overfishing are over in many regions. After stocks began to collapse in the 1970s, 1980s and 1990s, leading to the loss of many jobs, it gradually became clear to the fishing industry and policy-makers in various countries that overfishing is not only an environmental but also an economic problem. Some nations took the necessary steps to avoid any repeat of the situation. Australia, Canada, New Zealand and the USA, for example, developed fisheries management plans which limit catches to the extent that overfishing will be largely avoided in future. Europe has also learned from some of its mistakes. After massive overexploitation of the North Sea herring in the 1970s the fishery was completely closed for several years. The stocks recovered. Here too a fisheries management regime was introduced to prevent any renewed collapse. Even today, however, many other maritime regions and stocks are still not fished sustainably. One such area is the Bay of Biscay where the European hake (Merluccius merluccius) remains under heavy fishing pressure. Many stocks in the Mediterranean are also overfished.
Currently, therefore, the overall picture is mixed. Attempts are being made to maintain stocks in some regions through good management and sustainable fishing practices. In others, short-term profits still take priority over the precautionary approach to ensure the long-term productivity of stocks. It is therefore likely that stocks will continue to collapse. It is true that depleted stocks can recover when fishing is closed or drastically limited, but this can sometimes take many years. The herring stocks off the coast of Norway took about 20 years to recover from overfishing. Luckily, however, stocks of North Sea herring increased after just a few years, so that the fishing ban could be revoked. Nonetheless the effect of overfishing on the fishing industry is the loss of previously productive stocks for an extended period of time.
- 3.7 > The FAO divides the oceans into 19 major fishing areas which differ markedly in their annual catches (in tonnes living weight). The bar charts show the conditions in the corresponding maritime regions. The FAO figures (based on about 500 stocks) are compared with those of an American-German research group (based on about 2000 stocks). Despite the fact that the stock conditions were ascertained using different methods, it is still possible to compare the datasets. The Arctic is not shown in detail due to its limited catches. The red figures show the FAO number of the corresponding area. These areas differ considerably in their level of productivity. The coastal areas, or more accurately the continental shelves, are usually much more productive than the open seas. In FAO area 81, for example, there are few shelf areas, and the catch is correspondingly low, but the fish stocks are in a good condition (according to FAO data). Therefore, a low catch is not necessarily indic-ative of poor stock condition.
Around the world – the FAO fishing areasThe FAO divides the oceans into 19 major fishing areas. This regional classification has evolved over time. It simplifies the collection of data on fish catches, because the regional authorities and fishery associations work closely together. Other divisions – based on large-scale marine ecosystems, for example – might appear to make more sense today. Nonetheless, the FAO’s traditional division is still an effective way of making a global comparison. The 19 regions are in turn divided into three categories. The first comprises areas where the catches have been fluctuating since 1950. The second consists of areas where catches have fallen over the years, and the third category covers areas where catches have continuously increased. Here again the FAO bases its analysis on the roughly 500 fish stocks for which reliable stock calculations are available. However, four of the 19 areas – the Arctic and the three Antarctic areas – are not considered in more detail below, either because there is little fishing in these regions or because few of the stocks are exploited for commercial purposes.
Areas with fluctuating catch volumesThe first group includes the Eastern Central Atlantic (FAO fishing area 34), the Southwest Atlantic (41), the Northwest Pacific (61), the Northeast Pacific (67), the Eastern Central Pacific (77) and the Southeast Pacific (87). In the past five years these areas provided, on average, 52 per cent of the total global catch volume.
The most important area today is the Northwest Pacific. In 2010 a total of 21 million tonnes of fish were caught in this region – more than a quarter of the world’s total marine catch. Small pelagic fish such as the Japanese anchovy make up the largest proportion of the total catch. The Eastern Central Pacific and the Southeast Pacific are also prolific due to the nutrient-rich upwelling areas off the coast of South America. Catches are prone to huge fluctuations, sometimes from one year to the next. One reason for this is the large numbers of small schooling fish (sardines and anchovies), stocks of which rely heavily on the current in the upwelling areas. Nutrient-rich water rises to the surface from the depths, stimulating the growth and reproduction of the plankton on which fish feed. When the current weakens due to climatic fluctuations, there is less plankton and thus less food for the fish.
“Spawners” is the term used for sexually mature male and female fish which help to maintain stocks by producing young. If spawner numbers decrease as a result of intensive fishing or adverse environmental conditions, insuffi-cient young are produced and stocks can collapse.
- Compared with the general situation of world fish stocks, things are looking particularly grim in the Eastern Central Atlantic: 53 per cent of stocks in this area are considered overexploited, 43 per cent fully exploited and only 4 per cent non-fully exploited – off the coast of Senegal for example. The sardine (Sardina pilchardus) is the dominant species here. The Southwest Atlantic is also under heavy pressure. Important fish species are the Argentine hake and the anchovy off Brazil. Both are thought to be overfished. However, according to experts, the latter appears to be recovering. In this area, 50 per cent of stocks are considered overexploited, 41 per cent fully exploited and 9 per cent non-fully exploited. In contrast, the FAO data for the Northeast Pacific is comparatively positive. The annual catch peaked here in the 1980s. The largest proportion of the catch is made up of Alaska pollack, cod and hake. Today 80 per cent of the stocks in this region are considered fully exploited and 10 per cent each are over-exploited and non-fully exploited.
Areas with falling catchesThe areas in which catches have decreased over the years include the Northwest Atlantic (FAO fishing area 21), the Northeast Atlantic (27), the Western Central Atlantic (31), the Mediterranean and the Black Sea (both 37), the Southeast Atlantic (47) and the Southwest Pacific (81). In the past 5 years these areas provided an average 20 per cent of the world’s total catch. In some areas reduced catches were a result of fisheries management regulations, and stocks are expected to recover here. If the annual statistics indicate diminished catch volumes, this does not always mean that a stock is being depleted or has been overfished.
In the Northeast Atlantic, for instance, the pressure on cod, plaice and sole has been reduced. Management plans are in place for the most important stocks of these species. Fortunately the spawning stocks of the Northeast Arctic cod have increased again here – particularly in 2008. Apparently the stocks have recovered following the low levels of the 1960s to 1980s.
The future is looking a little brighter for the Northeast Arctic pollack and the Northeast Arctic haddock, but other stocks of these species continue to be overexploited in some regions of the Northeast Atlantic. Catches of blue whiting have decreased dramatically – from 2.4 million tonnes in 2004 to 540,000 tonnes in 2010 and 100,000 tonnes in 2011. This decline can be ascribed to the fisheries reacting too slowly to a sudden change in reproduction. Between the years of 1997 and 2004 the blue whiting for unknown reasons produced masses of young. During this period the species was fished intensively. But following a sudden drop in reproduction rates after 2004, the fishing industry continued to exploit the species at the same rate as before. The marked reduction of catch volumes in recent years, however, has helped the stocks to regenerate. In 2012 a harvest of almost 400,000 tonnes is expected.
The situation of some deep-sea fish species is critical. All in all, 62 per cent of the stocks assessed in the Northeast Atlantic are fully exploited, 31 per cent overexploited and 7 per cent non-fully exploited.
- Fish stocks also remain in a poor condition in the Northwest Atlantic. Cod and ocean perch, for example, have not yet recovered from the intensive fishing of the 1980s, despite the Canadian authorities having completely banned the commercial fishing of these species. Experts ascribe the situation to adverse environmental conditions and competition for food (Chapter 1). Other stocks which are protected by fisheries management regimes appear to be regenerating. These include the spiny dogfish, the yellowtail flounder, the Atlantic halibut, the Greenland halibut and the haddock. Stocks in the Northwest Atlantic are considered 77 per cent fully exploited, 17 per cent over-exploited and 6 per cent non-fully exploited.
Catch volumes in the Southeast Atlantic have declined considerably since the 1970s, from a previous 3.3 million tonnes to only 1.2 million tonnes in 2009. This can be ascribed partially to overfishing, and partially to catch reductions as a result of sustainable fisheries management. This applies in particular to the hake which is particularly important in this area. Thanks to the fishery measures introduced in 2006, some stocks of hake such as the deep sea Merluccius paradoxus off South Africa and the shallow water Merluccius capensis off Namibia appear to be recovering. In contrast, stocks of the formerly prolific South African sardine appear to be overexploited following a phase of intensive fishing. In 2004 the stock was classified as fully exploited. In the years since then, however, it has declined again as a result of adverse environmental conditions. This example highlights the speed at which a fully exploited stock can become overexploited, and the importance of forward-looking and sustainable fisheries management plans. The condition of the mackerel off the coast of Angola and Namibia has also deteriorated, since 2009 being considered overexploited.
The Mediterranean and the Black Sea are combined into a single FAO fishing area. Similarly, its situation is not particularly good. Of the stocks analyzed by the FAO, 50 per cent are overexploited, 33 per cent fully exploited and 17 per cent non-fully exploited. All stocks of the European hake (Merluccius merluccius) and the red mullet (Mullus barbatus) are classified as overexploited. Too little information is available about the condition of the sea breams and sole to categorize, but these are also suspected to be overexploited. The most significant stocks of small pelagic fish (sardines and anchovies) are considered fully exploited or overexploited.
Areas with increasing catchesIn only three of the FAO major fishing areas have catches been continuously increasing since the 1950s. These are the Western Central Pacific (FAO fishing area 71), the Eastern Indian Ocean (57) and the Western Indian Ocean (51). Catch volumes in the Western Central Pacific have constantly increased since 1970 to a peak of 11.7 million tonnes in 2010 – about 14 per cent of the total global catch. The situation has changed in the meantime, however, and stocks are now in a critical condition. Most are assessed as fully exploited and overexploited – particularly in the western regions of the South China Sea. It is thought that the high annual catches are due to China’s intensive fishing industry expanding into this area where there was little commercial fishing in the past. But the FAO points out that the high catch numbers could be misleading. For many years China’s catch statistics were adjusted upwards to comply with official output targets. It is assumed that fish were counted twice during transportation. For this reason it is conceivable that flawed data is masking an actual trend reversal – i.e. a reduction of fish stocks in the Western Central Pacific region. The annual catch in the Eastern Indian Ocean has also escalated over the years, and this trend is continuing. Between 2007 and 2010 alone, the catch volume increased by 17 per cent. In the Bay of Bengal and the Andaman Sea catch volumes are steadily increasing. About 42 per cent, however, is not ascribed to any specific species and simply registered as “marine fishes not identified”. This practice gives cause for concern because it is then impossible to assess the stocks of the different fish species in this heavily exploited region.
- Each of the FAO’s 19 major fishing areas comprises numerous sub-areas which are developing in different ways. Even when the total catch is increasing in one particular area, the trend for stocks of individual sub-areas can be the exact opposite. For instance, the catch volume in the Eastern Indian Ocean is increasing overall, but that of one sub-area, Australia’s Exclusive Economic Zone (EEZ), is decreasing in response to management plans. As far as the protection of fish stocks goes, Australia and New Zealand are now regarded as models of best practice. The trigger was a 2005 ministerial decision which ended overfishing in the EEZ and made it possible for stocks to recover.
The Western Indian Ocean has long been considered an area in which the catches have increased appreciably. A temporary peak was reached in 2006. Since then, catch volumes have slightly decreased. The volume for 2010 was 4.3 million tonnes. Current investigations show that the widespread Narrow-barred Spanish mackerel (Scomberomorus commerson) found in the Red Sea, the Persian Gulf, the Gulf of Oman and off India and Pakistan, is overfished. Catch figures from these areas are incomplete, making it difficult to estimate the population. Attempts are being made to gather valid data in other regions. The Southwest Indian Ocean Fisheries Commission responsible for the southwestern sub-area of the Western Indian Ocean carried out a systematic estimate of 140 species in 2010. Although there are some gaps in the data, the attempt to assess the region’s stocks deserves recognition. Overall, 65 per cent of the stocks in the Western Indian Ocean are fully exploited, 29 per cent overexploited and 6 per cent non-fully exploited.
Alien species add to the pressureAlready weakened fish stocks in some maritime regions are faced with the additional threat of alien species. Predators which feed on the fish, eggs and larvae of weakened stocks are particularly problematic, and competitors for food can play further havoc with depleted stocks. The situation becomes critical when the alien species thrives under its new living conditions and begins to reproduce vigorously. For example, alien species migrate from the Red Sea and through the Suez Canal into the Mediterranean. Some of them are apparently supplanting the native species of the eastern Mediterranean. The anchovy and sprat stocks of the Black Sea collapsed in the 1990s. This was due partly to overexploitation and partly to a type of fist-sized comb jellyfish introduced in the ballast water from ship tanks further undermining the already low fish stocks. The swarms of jellyfish ate the fish eggs and larvae en masse, biologists believe. Stocks have still not fully recovered. They are considered either fully exploited or still overexploited.
A closer look at the different speciesTaking a closer look at the individual fishing areas of the world, it becomes clear that there is no simple response to the question of how the fish are faring. It’s a complex situation. Without doubt many stocks are overexploited or have collapsed. But others are recovering thanks to sustainable fisheries management regimes. By way of illustration, the following section describes some individual fish species and their status – including the most important species with the highest total catch volumes. These fish species make up about 25 per cent of the world’s total fish catch. Most of their stocks are considered fully exploited or overexploited.
- 3.10 > Tins of tuna generally contain the flesh of widespread species such as the skipjack tuna. Nonetheless, consumers should ensure that the products they buy are from sustainable fisheries.
The Peruvian anchovy – sometimes more, sometimes lessThe development of the Peruvian anchovy (Engraulis ringens) is interesting. In terms of catch, it is the most important fish in the world. Large amounts are processed into fishmeal and fish oil to be fed to larger farmed fish in aquaculture operations. The largest volume ever caught, around 13 million tonnes, was landed in 1971. Today this would equate to a quarter of the global fish catch – excluding catches of other marine fauna such as mussels and squid. In the 1980s, the stocks crashed to about a tenth of this record level, not only as a result of intensive fishing but probably also because of a lack of food caused by the El Niño climatic phenomenon. The stocks later recovered. A new annual record of 12.5 million tonnes was reached in 1994. Since 2004, catch volumes have been dropping again, once more mainly due to El Niño. This anchovy example clearly shows the extent to which stocks can fluctuate. It also illustrates the vast amounts of fish which humans are removing from the seas; when adverse environmental conditions are added to the equation even vast stocks can be decimated. This example also teaches us that a stock can regenerate rapidly due to the ability of the fish to reproduce profusely.
Other species of fish and stocks, however, are not capable of recovering so quickly from overfishing. One example of this is the Northeast Atlantic mackerel.
- 3.11 > The ten most important ocean fish species and their worldwide catch totals. As a result of the El Niño climatic phenomenon, catches of the Peruvian anchovy in particular fluctuate from year to year.
The Northeast Atlantic mackerel – departure from the North SeaThe Northeast Atlantic mackerel (Scomber scombrus) fishery comprises three components: the western, the southern and the North Sea stock. Each has its own spawning grounds. The North Sea mackerel spawn along the east coast of Britain, the southern component in the Bay of Biscay and off the Iberian Peninsula and the western component to the west of the British Isles and Ireland.
In spring, when the plankton proliferates in response to rising temperatures, the mackerel of all three stocks gather in large hunting schools and migrate to the region between the Shetland Islands and Norway. They later gradually leave this nutrient-rich summer feeding area to spawn in the three regions mentioned above. They display an amazing swarming instinct: by no means all the first-time spawners return to their traditional spawning grounds, but often follow the majority of the mackerel. The North Sea mackerel used to be the largest component, so many first-time spawners were attracted to the North Sea. However, stocks of this component collapsed in the 1970s due to overfishing.
- Although the fishery was completely closed, the component has still not recovered. The western stock component then became the most prominent. The repercussions are clear: many mackerel which today begin their lives in the North Sea follow the main flow of fish towards the west when they first spawn. This occurs even in good years. Even when there are plenty of young fish in the North Sea most of them migrate westwards to spawn. The fact that there are still mackerel in the North Sea presumably means that a certain proportion of them continue to frequent the spawning grounds on England’s east coast. The question is whether a major mackerel stock will ever again be able to establish itself in the North Sea. It is interesting that the Northeast Atlantic mackerel has apparently been increasingly orienting itself towards the west in recent years. The early-summer migration has been taking them more regularly into Icelandic waters. As a result, Iceland’s mackerel catches have soared from 4000 to 200,000 tonnes in only three years. Scientists are worried about the development because for years now too many mackerel have been caught. The reason is that the littoral states – the Faroes, Iceland, Norway, Russia and the European Union – cannot agree on lower catches. Each nation sets its own limits. When added together the total catch far exceeds the annual tonnage recommended by scientists. Fears that Northeast Atlantic mackerel stocks will be completely overexploited in the coming years are therefore justified.
The European hake (southern stock) – haggling over catch numbersThe future of the European hake (southern stock) in the Bay of Biscay and west of the Iberian Peninsula is also uncertain. This is a classic example of how difficult it is to accurately assess a stock. And it also shows that if in doubt, a fishing nation tends to continue fishing rather than protect a fish population. The hake debate is difficult, mainly because the species seems to have been proliferating more rapidly over the past two years than had been observed previously. Its spawning biomass levels are increasing. ICES scientists, however, believe that for some time now, probably since the turn of the century, the stock has been overfished. The ICES fish abundance estimates have revealed that three times more hake has probably been caught than the stock can sustain over the long term. After tough and protracted negotiations with Spain, the European Commission in 2005 finally succeeded in establishing a management plan. But the ICES experts consider this inadequate, because it aims to reduce catches very slowly. In purely arithmetical terms, the stock could, at some stage, recover. However, the scientists claim that such an increase in the hake population would be so minimal as to be scarcely perceptible. Accordingly, it would be impossible to predict any stock recovery within the next ten years.
For this reason, many experts consider the management plan absurd, providing the hake with little protection. Nonetheless, Spain is persisting with it based on the evidence of the current increase in spawning biomass. The ICES believes that too many fish are still being caught, and it is simply a matter of luck that spawning stocks are expanding. They claim that hake numbers are growing in spite of and not because of the management plan. Spain is unlikely to back down. The data it has submitted to the ICES for 2012 is incomplete and is of little use in this form. This has led to the current heated debate taking place between the ICES and Spain.
- 3.12 > Resolute fisheries management can ensure the recovery of a fish stock. After the North Sea herring was overfished in the 1960s (as revealed by the drop in spawning biomass), the fishery was completely closed. The stock, particularly the numbers of sexually mature fish (spawners), regenerated. After renewed over-fishing in the 1990s a management plan was agreed in 1997, which once again limited catches. The spawning stock was able to recover. The reduction of spawning biomass since 2002 can presumably be ascribed to climatic changes.
The North Sea herring – recovery is possibleThe example of the North Sea herring shows that a stock can recover if it is given a chance. Within a few years of the introduction of seine fishing in the 1960s, the stocks collapsed. The herring fishery was therefore completely closed between 1977 and 1981 – a measure which was both logical and correct. The stock recovered. In the early 1990s the spawning biomass level reached a new high. The next crisis followed not long after. This time many juvenile fish were captured in the nets as bycatch, leaving fewer fish to grow to maturity and rebuild depleted populations. As a result the spawning biomass dropped markedly once again, and stocks reached another low point in the mid-1990s. But this time reaction was swift. In mid-season 1997 catch amounts were again cut back drastically, and stocks recovered.
A purse seine is a net that is used to encircle a school of fish. The net is then drawn together to retain the fish by using a line at the bottom, allowing the net to be closed like a purse.
- This example shows that the development of a stock can be very specifically controlled by restrictions and bans on fishing, resulting in positive change. Since 2002 the spawning biomass has again been dropping – most probably due to natural climatic fluctuations. Apparently the reproduction of the herring is partially connected to the North Atlantic Oscillation (NAO), a large-scale fluctuation in atmospheric pressure which occurs at regular intervals. This is leading to more differences of opinion between the ICES which makes the recommendations, and the EU Council of Ministers which is responsible for fisheries management in the North Sea. The positive stock development prompted the Council of Ministers in 2011 to set higher catches than envisaged in the management plan and recommended by ICES. The ICES is urging that catches should remain as they were, in spite of the good spawning stocks. Especially in good times a management plan should be complied with, it claims, so that stocks can further regenerate and cushion years with poor reproduction.