Fisheries and climate change

Rising ocean temperatures[2] and ocean acidification[3] are radically altering aquatic ecosystems. Climate change is modifying fish distribution[4] and the productivity of marine and freshwater species. This has impacts on the sustainability of fisheries and aquaculture, on the livelihoods of the communities that depend on fisheries, and on the ability of the oceans to capture and store carbon (biological pump). The effect of sea level rise means that coastal fishing communities are in the front line of climate change, while changing rainfall patterns and water use impact on inland (freshwater) fisheries and aquaculture. The full relationship between fisheries and climate change is difficult to explore due to the context of each fishery and the many pathways that climate change affects.[5]

Bangladesh Fishing 2006
Fishing with a lift net in Bangladesh. Coastal fishing communities in Bangladesh are vulnerable to flooding from sea-level rises.[1]

Role of oceans

Maldives - Kurumba Island
Island with fringing reef in the Maldives. Coral reefs are dying around the world.[6]

Oceans and coastal ecosystems play an important role in the global carbon cycle and have removed about 25% of the carbon dioxide emitted by human activities between 2000 and 2007 and about half the anthropogenic CO2 released since the start of the Industrial Revolution. Rising ocean temperatures and ocean acidification means that the capacity of the ocean carbon sink will gradually get weaker,[7] giving rise to global concerns expressed in the Monaco[8] and Manado[9] Declarations. Healthy ocean ecosystems are essential for the mitigation of climate change.[10] Coral reefs provide habitat for millions of fish species and with no change it can provoke these reefs to die.

Impact on fish production

The rising ocean acidity makes it more difficult for marine organisms such as shrimps, oysters, or corals to form their shells – a process known as calcification. Many important animals, such as zooplankton, that forms the base of the marine food chain have calcium shells. Thus the entire marine food web is being altered – there are ‘cracks in the food chain’. As a result, the distribution,[11] productivity, and species composition of global fish production is changing,[12] generating complex and inter-related impacts[13] on oceans, estuaries, coral reefs, mangroves and sea grass beds that provide habitats and nursery areas for fish. Changing rainfall patterns and water scarcity is impacting on river and lake fisheries and aquaculture production.[14][15] After the ice age about 200,000 years ago, the global air temperature has risen 3 degrees, leading to an increase in sea temperatures.[16]

Fish catch of the global ocean is expected to decline by 6 percent by 2100 and by 11 percent in tropical zones. Diverse models predict that by 2050, the total global fish catch potential may vary by less than 10 percent depending on the trajectory of greenhouse gas emissions, but with very significant geographical variability. Decreases in both marine and terrestrial production in almost 85 percent of coastal countries analysed are predicted, varying widely in their national capacity to adapt.[17]

Fish populations of skipjack tuna and bigeye tuna are expected to be displaced further to the east due to the effects of climate change on ocean temperatures and currents.[18] This will shift the fishing grounds toward the Pacific islands and away from its primary owner of Melanesia, disrupting western Pacific canneries, shifting tuna production elsewhere, and having an uncertain effect on food security.

Species that are over-fished, such as the variants of Atlantic cod, are more susceptible to the effects of climate change. Over-fished populations have less size, genetic diversity, and age than other populations of fish.[19] This makes them more susceptible to environment related stress, including those resulting from climate change. In the case of Atlantic cod located in the Baltic Sea, which are stressed close to their upper limits, this could lead to consequences related to the population's average size and growth.

Due to climate change, the distribution of zooplankton has changed. Cool water cope-pod assemblages have moved north because the waters get warmer, they have been replaced by warm water cope-pods assemblages however it has a lower biomass and certain small species. Atlantic cod require a diet of large cope-pods but because they have moved pole-wards morality rates are high and as a result the recruitment of this cod has plummeted[20]

Impact on fishing communities

Fisherman Seychelles
Fisherman landing his catch, Seychelles

Coastal and fishing populations[21] and countries dependent on fisheries[22] are particularly vulnerable to climate change. Low-lying countries such as the Maldives[23] and Tuvalu are particularly vulnerable and entire communities may become the first climate refugees. Fishing communities in Bangladesh are subject not only to sea-level rise, but also flooding and increased typhoons. Fishing communities along the Mekong river produce over 1 million tons of basa fish annually and livelihoods and fish production will suffer from saltwater intrusion resulting from rising sea level and dams.[24]

While climate change increases the effects of human activities, the inverse is also applicable. Human activities also increase the impact of climate change. Human activity has been linked to lake nutrition levels, which high levels are correlated to increasing vulnerability to climate change. Lake Annecy, Lake Geneva, and Lake Bourget were subject to experiments related to their zooplankton.[25] Lake Geneva and Lake Bourget had relatively high levels of nutrients and responded at a significant level towards factors related to climate change, such as weather variability. Lake Annecy had the lowest amount of nutrition levels and responded comparatively poorly.

Fisheries and aquaculture contribute significantly to food security and livelihoods. Fish provides essential nutrition for 3 billion people and at least 50% of animal protein and minerals to 400 million people from the poorest countries.[26] This food security is threatened by climate change and the increasing world population. Climate change changes several parameters of the fishing population: availability, stability, access, and utilization.[27] The specific effects of climate change on these parameters will vary widely depending on the characteristics of the area, with some areas benefiting from the shift in trends and some areas being harmed based on the factors of exposure, sensitivity, and ability to respond to said changes.The lack of oxygen in warmer waters will possibly lead to the extinction of aquatic animals[28] Worldwide food security may not change significantly, however rural and poor populations would be disproportionately and negatively affected based on this criteria, as they lack the resources and manpower to rapidly change their infrastructure and adapt. Over 500 million people in developing countries depend, directly or indirectly, on fisheries and aquaculture for their livelihoods - aquaculture is the world’s fastest growing food production system, growing at 7% annually and fish products are among the most widely traded foods, with more than 37% (by volume) of world production traded internationally.[29]

Adaptation and mitigation

The impacts of climate change can be addressed through adaptation and mitigation. The costs and benefits of adaptation are essentially local or national, while the costs of mitigation are essentially national whereas the benefits are global. Some activities generate both mitigation and adaptation benefits, for example, the restoration of mangrove forests can protect shorelines from erosion and provide breeding grounds for fish while also sequestering carbon.


Several international agencies, including the World Bank and the Food and Agriculture Organization[30] have programs to help countries and communities adapt to global warming, for example by developing policies to improve the resilience[31] of natural resources, through assessments of risk and vulnerability, by increasing awareness[32] of climate change impacts and strengthening key institutions, such as for weather forecasting and early warning systems.[33] The World Development Report 2010 - Development and Climate Change, Chapter 3[34] shows that reducing overcapacity in fishing fleets and rebuilding fish stocks can both improve resilience to climate change and increase economic returns from marine capture fisheries by US$50 billion per year, while also reducing GHG emissions by fishing fleets. Consequently, removal of subsidies on fuel for fishing can have a double benefit by reducing emissions and overfishing.

Investment in sustainable aquaculture[35] can buffer water use in agriculture while producing food and diversifying economic activities. Algal biofuels also show potential as algae can produce 15-300 times more oil per acre than conventional crops, such as rapeseed, soybeans, or jatropha and marine algae do not require scarce freshwater. Programs such as the GEF-funded Coral Reef Targeted Research provide advice on building resilience and conserving coral reef ecosystems,[36] while six Pacific countries recently gave a formal undertaking to protect the reefs in a biodiversity hotspot – the Coral Triangle.[37]


The oceans have removed 50%[38] of the anthropogenic CO2, so the oceans have absorbed much of the impact of climate change. The famous White Cliffs of Dover illustrate how the ocean captures and buries carbon. These limestone cliffs are formed from the skeletons of marine plankton called coccoliths. Similarly, petroleum formation is attributed largely to marine and aquatic plankton further illustrating the key role of the oceans in carbon sequestration.

Exactly how the oceans capture and bury CO2 is the subject of intense research[39] by scientists worldwide, such as the Carboocean Project.[40] The current level of GHG emissions means that ocean acidity will continue to increase and aquatic ecosystems will continue to degrade and change. There are feedback mechanisms involved here. For example, warmer waters can absorb less CO2, so as ocean temperatures rise some dissolved CO2 will be released back into the atmosphere. Warming also reduces nutrient levels in the mesopelagic zone (about 200 to 1000 m deep). This in turn limits the growth of diatoms in favour of smaller phytoplankton that are poorer biological pumps of carbon. This inhibits the ability of the ocean ecosystems to sequester carbon as the oceans warm.[41] What is clear, is that healthy ocean and coastal ecosystems are necessary to continue the vital role of the ocean carbon sinks, as indicated, for example, by the Blue Carbon[42] assessment prepared by UNEP and the coastal carbon sinks report[43] of IUCN and growing evidence of the role of fish biomass[44] in the transport of carbon from surface waters to the deep ocean.

While the various carbon finance instruments include restoration of forests (REDD) and producing clean energy (emissions trading), few address the need to finance healthy ocean and aquatic ecosystems although these are essential for continued uptake of CO2 and GHGs. The scientific basis for ocean fertilization – to produce more phytoplankton to increase the uptake of CO2 – has been challenged, and proposals for burial of CO2 in the deep ocean have come under criticism from environmentalists.


Although there is a decline of fisheries due to climate change, a related cause for this decrease is due to over-fishing. Over-fishing exacerbates the effects of climate change by creating conditions that make a fishing population more sensitive to environmental changes. Studies show that the state of the ocean is causing fisheries to collapse, and in areas where fisheries have not yet collapsed, the amount of over-fishing that is done is having a significant impact on the industry.[45] Over-fishing is due to having access to the open sea, it makes it very easy for people to over fish, even if it is just for fun. There is also a high demand for sea food by fishermen, as well modern technology that has increased the amount of fish caught during each trip.[45]

If there was a specific amount of fish that people were allowed to catch then this could very well solve the problem of over fishing.[45] This type of limit system is in place in a few countries including New Zealand, Norway, Canada, and the United States. In these countries the limit system has successfully helped in fishing industries.[45] These types of limit systems are called Individual fishing quota. This means that the areas where this quota exist, the government has legal entity over it and in these boundaries they are entitled to utilize their ocean resources as they wish.[45]

See also


Definition of Free Cultural Works logo notext.svg This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 IGO License statement: In brief, The State of World Fisheries and Aquaculture, 2018, FAO, FAO. To learn how to add open license text to Wikipedia articles, please see this how-to page. For information on reusing text from Wikipedia, please see the terms of use.


  1. ^ Sarwar G.M. (2005). "Impacts of Sea Level Rise on the Coastal Zone of Bangladesh" (PDF). Lund University. Archived from the original (PDF) on 15 August 2012. Retrieved 10 September 2013. Masters thesis
  2. ^ Observations: Oceanic Climate Change and Sea Level Archived 2017-05-13 at the Wayback Machine In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. (15MB).
  3. ^ Doney, S. C. (March 2006). "The Dangers of Ocean Acidification" (PDF). Scientific American.
  4. ^ Cheung, W.W.L.; et al. (October 2009). "Redistribution of Fish Catch by Climate Change. A Summary of a New Scientific Analysis" (PDF). Pew Ocean Science Series. Archived from the original (PDF) on 2011-07-26.
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  7. ^ UNEP, FAO, IOC (2009-11-25). "Blue Carbon. The role of healthy oceans in binding carbon" (PDF).CS1 maint: Multiple names: authors list (link)
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  12. ^ FAO (2008) Report of the FAO Expert Workshop on Climate Change Implications for Fisheries and AquaculturMelanesiae Rome, Italy, 7–9 April 2008. FAO Fisheries Report No. 870.
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  20. ^ Richardson, A. J. (2008). "In hot water: Zooplankton and climate change". ICES Journal of Marine Science. 65 (3): 279–295. doi:10.1093/icesjms/fsn028.
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  22. ^ Allison, E.H.; et al. (2009). "Vulnerability of national economies to the impacts of climate change on fisheries" (PDF). Fish and Fisheries. 10 (2): 173–96. CiteSeerX doi:10.1111/j.1467-2979.2008.00310.x. Archived from the original (PDF) on 2011-07-26. Retrieved 2009-12-02.
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Other reading

Bioeconomics (fisheries)

Bioeconomics is closely related to the early development of theories in fisheries economics, initially in the mid-1950s by Canadian economists Scott Gordon (in 1954) and Anthony Scott (1955). Their ideas used recent achievements in biological fisheries modelling, primarily the works by Schaefer in 1954 and 1957 on establishing a formal relationship between fishing activities and biological growth through mathematical modelling confirmed by empirical studies, and also relates itself to ecology and the environment and resource protection.These ideas developed out of the multidisciplinary fisheries science environment in Canada at the time. Fisheries science and modelling developed rapidly during a productive and innovative period, particularly among Canadian fisheries researchers of various disciplines. Population modelling and fishing mortality were introduced to economists, and new interdisciplinary modelling tools became available for the economists, which made it possible to evaluate biological and economic impacts of different fishing activities and fisheries management decisions.

Catch reporting

Catch reporting is a part of Monitoring control and surveillance of Commercial fishing. Depending on national and local fisheries management practices, catch reports may reveal illegal fishing practices, or simply indicate that a given area is being overfished.

Data storage tag

A data storage tag (DST), also sometimes known as an archival tag, is a data logger that uses sensors to record data at predetermined intervals. Data storage tags usually have a large memory size and a long lifetime. Most archival tags are supported by batteries that allow the tag to record positions for several years. Alternatively some tags are solar powered and allow the scientist to set their own interval; this then allows data to be recorded for significantly longer than battery-only powered tags.

Destructive fishing practices

Destructive fishing practices are practices that easily result in irreversible damage to aquatic habitats and ecosystems. Many fishing techniques can be destructive if used inappropriately, but some practices are particularly likely to result in irreversible damage. These practices are mostly, though not always, illegal. Where they are illegal, they are often inadequately enforced.

Eel ladder

An eel ladder is type of fish ladder designed to help eels swim past barriers, such as dams and weirs or even natural barriers, to reach upriver feeding grounds. (Many eels are catadromous, living in fresh water but spawning at sea.) The basic design of an eel ladder has the eel swim over the barrier using an eel ascending ramp, which provides the eels a climbing substrate to "push against" while slithering upstream. For some higher barriers, elevator-style systems are also used.

An eel ladder typically consists of four parts: an eel ascending ramp, a supporting structure, a water-feeding system, and a side gutter. The eel ascending ramp can be a fairly simple construction, such as a hollowed out tree filled with recycled fishing net, or a more complex structure designed to accommodate specific species or ages of eels. The supporting structure mounts the ladder to the barrier. The rampside gutter provides an attraction flow to draw eels toward the ladder while the water-feeding system ensures the proper flow of water to the gutter.

European Fishery MLS

In European Union member states, there exists a standard set of minimum landing sizes (MLS) for all major species of finfish and shellfish. These MLS are set under EU Council Regulation 850/98.

Fish measurement

Fish measurement is the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.

Fish screen

A fish screen is designed to prevent fish from swimming or being drawn into an aqueduct, cooling water intake, intake tower, dam or other diversion on a river, lake or waterway where water is taken for human use. They are intended to supply debris-free water without harming aquatic life. Fish screens are typically installed to protect endangered species of fishes that would otherwise be harmed or killed when passing through industrial facilities such as steam electric power plants, hydroelectric generators, petroleum refineries, chemical plants, farm irrigation water and municipal drinking water treatment plants. However, many fish are killed or injured on screens or elsewhere in the intake structures.

Fish stock

Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters (growth, recruitment, mortality and fishing mortality) are traditionally regarded as the significant factors determining the stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored.

Fishery Resources Monitoring System

The Fishery Resources Monitoring System (FIRMS) is a partnership of intergovernmental fisheries organizations that share a wide range of high-quality information on the global monitoring and management of marine fishery resources.

GIS and aquatic science

Geographic Information Systems (GIS) has become an integral part of aquatic science and limnology. Water by its very nature is dynamic. Features associated with water are thus ever-changing. To be able to keep up with these changes, technological advancements have given scientists methods to enhance all aspects of scientific investigation, from satellite tracking of wildlife to computer mapping of habitats. Agencies like the US Geological Survey, US Fish and Wildlife Service as well as other federal and state agencies are utilizing GIS to aid in their conservation efforts.

GIS is being used in multiple fields of aquatic science from limnology, hydrology, aquatic botany, stream ecology, oceanography and marine biology. Applications include using satellite imagery to identify, monitor and mitigate habitat loss. Imagery can also show the condition of inaccessible areas. Scientists can track movements and develop a strategy to locate locations of concern. GIS can be used to track invasive species, endangered species, and population changes.

One of the advantages of the system is the availability for the information to be shared and updated at any time through the use of web-based data collection.

Incidental catch

In fishing, incidental catch is that part of the catch which was not originally targeted, but was caught and retained anyway. It can be contrasted with discards, which is that part of the catch which was not originally targeted, but was caught and returned to the sea, and bycatch, which is for all the species caught apart from the targeted species.

The operational definitions used by the FAO for incidental catch and other related catches are as follows:

Target catch: The catch of a species or species assemblage which is primarily sought in a fishery, such as shrimp, flounders, cods

Incidental catch: Retained catch of non-targeted species

Discarded catch (usually shortened to discards): That portion of the catch returned to the sea as a result of economic, legal, or personal considerations.

Bycatch: Discarded catch plus incidental catch.

Minimum landing size

The minimum landing size (MLS) is the smallest fish measurement at which it is legal to keep or sell a fish. What the MLS is depends on the species of fish. Sizes also vary around the world, as they are legal definitions which are defined by the local regulatory authority. Commercial trawl and seine fisheries can control the size of their catch by adjusting the mesh size of their nets.

European Union – The European Fishery MLS applies to all EU member states.

Ocean Outcomes

Ocean Outcomes (O2) is an international nonprofit organization which works with commercial fisheries, seafood industry, local communities, government, NGOs, and other fishery stakeholders to develop and implement solutions towards more sustainable fisheries. O2's work includes fishery assessments, fishery improvement projects (FIPs), buyer engagement programs, supply chain analysis, and other contractual fishery-related work. Founded in 2015, O2 has team members and fishery projects across Northeast Asia, including on the ground operations in China, Japan, and South Korea.

Particle (ecology)

In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater. However, they eventually settle (rate determined by Stokes' law) and accumulate as sediment. Some can enter the atmosphere through wave action where they can act as cloud condensation nuclei (CCN). Many organisms filter particles out of the water with unique filtration mechanisms (filter feeders). Particles are often associated with high loads of toxins which attach to the surface. As these toxins are passed up the food chain they accumulate in fatty tissue and become increasingly concentrated in predators (see bioaccumulation). Very little is known about the dynamics of particles, especially when they are re-suspended by dredging. They can remain floating in the water and drift over long distances. The decomposition of some particles by bacteria consumes a lot of oxygen and can cause the water to become hypoxic.

Pulse fishing

Pulse fishing is a fisheries management technique for preventing fish stocks from being overfished by periodically permitting a cycle of fishing followed by a fallow period which allows stocks to reconstitute. It should not to be confused with electric pulse fishing which is a fishing technique which involves pulsing electric currents.

Shrimp-Turtle Case

In 1994, the WTO intervened to address member concerns regarding the import of shrimp and its impact on turtles. This became known as the Shrimp and Turtle case. The ruling was adopted on November 6, 1998. However, Malaysia persisted in their complaint and initiated DSU Article 21.5 proceedings against the U.S. in 2001, but the U.S. prevailed in those hearings.

Sustainable seafood advisory lists and certification

Sustainable seafood advisory lists and certification are programs aimed at increasing consumer awareness of the environmental impact and sustainability of their seafood purchasing choices.

California-based Seafood Watch and Marine Conservation Society's fish online are some of the best-known guides. One of the best-known certification programs is Marine Stewardship Council's scheme for consumer seafood products.

Other programs include regional guides, such as that produced by the Australian Marine Conservation Society (AMCS). In Canada, SeaChoice produces assessments and recommendations using the traffic light system, while recommendation of restaurants is done by Vancouver Aquarium's Ocean Wise.

Water column

A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment. Descriptively, the deep sea water column is divided into five parts—pelagic zones (from Greek πέλαγος (pélagos), 'open sea')—from the surface to below the floor, as follows: epipelagic, from the surface to 200 meters below the surface; mesopelagic, from 200 to 1000 meters below the surface; bathypelagic, from 1000 to 4000 meters below the surface; abyssopelagic, from 4000 meters below the surface to the level sea floor; hadopelagic, depressions and crevices below the level sea floor.

The concept of water column is useful since many aquatic phenomena are explained by the incomplete vertical mixing of chemical, physical or biological parameters. For example, when studying the metabolism of benthic organisms, it is the specific bottom layer concentration of available chemicals in the water column that is meaningful, rather than the average value of those chemicals throughout the water column.

Water columns are used chiefly for environmental studies evaluating the stratification or mixing of the thermal or chemically stratified layers in a lake, stream or ocean: for example, by wind-induced currents. Some of the common parameters analyzed in the water column are pH, turbidity, temperature, hydrostatic pressure, salinity, total dissolved solids, various pesticides, pathogens and a wide variety of chemicals and biota.

The term water column is also commonly used in scuba diving to describe the vertical space through which divers ascend and descend.

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