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Fisheries are affected by climate change in many ways: marine aquatic ecosystems are being affected by rising ocean temperatures, [2] ocean acidification [3] and ocean deoxygenation, while freshwater ecosystems are being impacted by changes in water temperature, water flow, and fish habitat loss. [4] These effects vary in the context of each fishery. [5] Climate change is modifying fish distributions [6] and the productivity of marine and freshwater species. Climate change is expected to lead to significant changes in the availability and trade of fish products. [7] The geopolitical and economic consequences will be significant, especially for the countries most dependent on the sector. The biggest decreases in maximum catch potential can be expected in the tropics, mostly in the South Pacific regions. [7] : iv
The impacts of climate change on ocean systems 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 significantly impacted by climate change, while changing rainfall patterns and water use impact on inland freshwater fisheries and aquaculture. [8] Increased risks of floods, diseases, parasites and harmful algal blooms are climate change impacts on aquaculture which can lead to losses of production and infrastructure. [7]
Oceans and coastal ecosystems play an important role in the global carbon cycle and in Carbon sequestration. Rising ocean temperatures and ocean acidification are the results of higher levels of greenhouse gases in the atmosphere. 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. [11] Furthermore, the rise in sea levels also affects other ecosystems such as mangroves and marshes, making them experience a lack of both land and hinterland for the purpose to migrate. [12]
Among the effects of climate change on oceans are an increase of ocean temperatures, more frequent marine heatwaves, ocean acidification, a rise in sea levels, sea ice decline, increased ocean stratification, reductions in oxygen levels, changes to ocean currents including a weakening of the Atlantic meridional overturning circulation. [13] All these changes have knock-on effects which disturb marine ecosystems. The primary factor causing these changes is the Earth warming due to human-caused emissions of greenhouse gases, such as carbon dioxide and methane. This leads inevitably to ocean warming, because the ocean is taking up most of the additional heat in the climate system. [14] The ocean absorbs some of the extra carbon dioxide in the atmosphere and this causes the pH value of the ocean to drop. [15] It is estimated that the ocean absorbs about 25% of all human-caused CO2 emissions. [15]
Ocean temperature stratification increases as the ocean surface warms due to rising air temperatures. [16] : 471 The decline in mixing of the ocean layers stabilises warm water near the surface while reducing cold, deep water circulation. The reduced up and down mixing reduces the ability of the ocean to absorb heat, directing a larger fraction of future warming toward the atmosphere and land. The amount of energy available for tropical cyclones and other storms is expected to increase, while nutrients for fish in the upper ocean layers are expected to decrease, as is the ocean's capacity to store carbon. [17] At the same time, contrasts in salinity are increasing: salty areas are becoming saltier and fresher areas less salty. [18]The fishing industry sector is a small contributor to greenhouse gas emissions overall but nevertheless there are options for reducing fuel use and greenhouse gas emissions. [7] : v For example, about 0.5 percent of total global CO2 emissions in 2012 were caused by fishing vessels (including inland vessels): 172.3 million tonnes of CO2. [7] When looking at the aquaculture industry, it was estimated that 385 million tonnes of CO2 equivalent (CO2 e) were emitted in 2010. This equates to around 7 percent of the emissions from agriculture. [7] : v
The rising ocean acidity makes it more difficult for marine organisms such as shrimp, 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'. [19] As a result, the distribution, [20] productivity, and species composition of global fish production is changing, [21] generating complex and inter-related impacts [22] 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. [23] [24] After the Last Glacial Maximum of about 21,000 years ago, the global average air temperature has risen approximately 3 degrees, leading to an increase in sea temperatures. [25]
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. [26]
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. [27] 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. [28]
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. [29] 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. [30]
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. This movement of copepods could have large impacts on many systems, especially high trophic level fish. [31] For example, 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 [32]
Increase in water temperature as a result of climate change will alter the productivity of aquatic ecosystems. flourish may be undesirable or even harmful. For example, the large fish predators that require cool water may be lost from smaller lakes as surface water temperature warms, and this may indirectly cause more blooms of nuisance algae, which can reduce water quality and pose potential health problems. [33]
Coastal and fishing populations [34] and countries dependent on fisheries [35] are particularly vulnerable to climate change. Low-lying countries such as the Maldives [36] 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. [37] In rural Alaska, residents of the Noatak and Selawik villages struggle with unpredictable weather, changes in fish abundance and movement, and boat access changes due to climate change. [38] These impacts significantly impact sustainability and subsistence practices. [38]
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. [39] 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. [40] 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 [41]
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. In Bangladesh, Cambodia, Gambia, Ghana, Sierra Leone or Sri Lanka, the dependency on fish for protein intake is over 50%. [42] 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. [43]
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. Excess nutrients in water bodies, or eutrophication, can result in more algae and plant growth which can be harmful to humans, aquatic communities, and even birds. [44]
Climate change will also have an impact on recreational fisheries and commercial fisheries, as shifts in distribution could lead to changes in popular fishing locations, economic changes in fishing communities, and increased accessibility of fisheries in the North. [45]
The change in temperature and decrease in oxygen is expected to occur too quickly for effective adaptation of affected species. [46] Fishes can migrate to cooler places, but there are not always appropriate spawning sites. [46]
Several international agencies, including the World Bank and the Food and Agriculture Organization [47] have programs to help countries and communities adapt to global warming, for example by developing policies to improve the resilience [48] of natural resources, through assessments of risk and vulnerability, by increasing awareness [49] of climate change impacts and strengthening key institutions, such as for weather forecasting and early warning systems. [50] The World Development Report 2010 – Development and Climate Change, Chapter 3 [51] 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.[ citation needed ]
Investment in sustainable aquaculture [52] 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, [53] while six Pacific countries recently gave a formal undertaking to protect the reefs in a biodiversity hotspot – the Coral Triangle. [54]
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 [55] .[ citation needed ]
Although there is a decline of fisheries due to climate change, a related cause for this decrease is due to over-fishing. [56] 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. Fishing that is destructive and unsustainable affects biodiversity. [57] Minimizing over-fishing and destructive fishing will increase Ocean resilience to climate change hence mitigating climate change
This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 IGO( license statement/permission ). Text taken from In brief, The State of World Fisheries and Aquaculture, 2018 , FAO, FAO.
Aquaculture, also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants. Aquaculture involves cultivating freshwater, brackish water and saltwater populations under controlled or semi-natural conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish. Mariculture, commonly known as marine farming, refers specifically to aquaculture practiced in seawater habitats and lagoons, as opposed to freshwater aquaculture. Pisciculture is a type of aquaculture that consists of fish farming to obtain fish products as food.
Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place. Commercial fisheries include wild fisheries and fish farms, both in freshwater waterbodies and the oceans. About 500 million people worldwide are economically dependent on fisheries. 171 million tonnes of fish were produced in 2016, but overfishing is an increasing problem — causing declines in some populations.
Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae that live inside their tissue, causing the coral to turn white. The zooxanthellae are photosynthetic, and as the water temperature rises, they begin to produce reactive oxygen species. This is toxic to the coral, so the coral expels the zooxanthellae. Since the zooxanthellae produce the majority of coral colouration, the coral tissue becomes transparent, revealing the coral skeleton made of calcium carbonate. Most bleached corals appear bright white, but some are blue, yellow, or pink due to pigment proteins in the coral.
Southeast Asian coral reefs have the highest levels of biodiversity for the world's marine ecosystems. They serve many functions, such as forming the livelihood for subsistence fishermen and even function as jewelry and construction materials. Corals inhabit coastal waters off of every continent except Antarctica, with an abundance of reefs residing along Southeast Asian coastline in several countries including Indonesia, the Philippines, and Thailand. Coral reefs are developed by the carbonate-based skeletons of a variety of animals and algae. Slowly and overtime, the reefs build up to the surface in oceans. Coral reefs are found in shallow, warm salt water. The sunlight filters through clear water and allows microscopic organisms to live and reproduce. Coral reefs are actually composed of tiny, fragile animals known as coral polyps. Coral reefs are significantly important because of the biodiversity. Although the number of fish are decreasing, the remaining coral reefs contain more unique sea creatures. The variety of species living on a coral reef is greater than anywhere else in the world. An estimation of 70-90% of fish caught are dependent on coral reefs in Southeast Asia and reefs support over 25% of all known marine species. However, those sensitive coral reefs are facing detrimental effects on them due to variety of factors: overfishing, sedimentation and pollution, bleaching, and even tourist-related damage.
Ocean acidification is the decrease in the pH of the Earth’s ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ocean acidification, with atmospheric carbon dioxide (CO2) levels exceeding 410 ppm (in 2020). CO2 from the atmosphere is absorbed by the oceans. This produces carbonic acid (H2CO3) which dissociates into a bicarbonate ion (HCO−3) and a hydrogen ion (H+). The presence of free hydrogen ions (H+) lowers the pH of the ocean, increasing acidity (this does not mean that seawater is acidic yet; it is still alkaline, with a pH higher than 8). Marine calcifying organisms, such as mollusks and corals, are especially vulnerable because they rely on calcium carbonate to build shells and skeletons.
Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, lagoons. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web.
The environmental impact of fishing includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; as well as the impact of industrial fishing on other elements of the environment, such as bycatch. These issues are part of marine conservation, and are addressed in fisheries science programs. According to a 2019 FAO report, global production of fish, crustaceans, molluscs and other aquatic animals has continued to grow and reached 172.6 million tonnes in 2017, with an increase of 4.1 percent compared with 2016. There is a growing gap between the supply of fish and demand, due in part to world population growth.
A wild fishery is a natural body of water with a sizeable free-ranging fish or other aquatic animal population that can be harvested for its commercial value. Wild fisheries can be marine (saltwater) or lacustrine/riverine (freshwater), and rely heavily on the carrying capacity of the local aquatic ecosystem.
The Coral Triangle (CT) is a roughly triangular area in the tropical waters around the Philippines, Indonesia, Malaysia, Papua New Guinea, the Solomon Islands and Timor-Leste. This area contains at least 500 species of reef-building corals in each ecoregion. The Coral Triangle is located between the Pacific and Indian oceans and encompasses portions of two biogeographic regions: the Indonesian-Philippines Region, and the Far Southwestern Pacific Region. As one of eight major coral reef zones in the world, the Coral Triangle is recognized as a global centre of marine biodiversity and a global priority for conservation. Its biological resources make it a global hotspot of marine biodiversity. Known as the "Amazon of the seas" (by analogy to the Amazon rainforest in South America), it covers 5.7 million square kilometres (2,200,000 sq mi) of ocean waters. It contains more than 76% of the world's shallow-water reef-building coral species, 37% of its reef fish species, 50% of its razor clam species, six out of seven of the world's sea turtle species, and the world's largest mangrove forest. In 2014, the Asian Development Bank (ADB) reported that the gross domestic product of the marine ecosystem in the Coral Triangle is roughly $1.2 trillion per year and provides food to over 120 million people. According to the Coral Triangle Knowledge Network, the region annually brings in about $3 billion in foreign exchange income from fisheries exports, and another $3 billion from coastal tourism revenues.
Ocean deoxygenation is the reduction of the oxygen content of the global oceans and coastal zones due to human activities as a consequence of anthropogenic emissions of carbon dioxide and eutrophication-driven excess production. It is manifest in the increasing number of coastal and estuarine hypoxic areas, or dead zones, and the expansion of oxygen minimum zones (OMZs) in the world's oceans. The decrease in oxygen content of the oceans has been fairly rapid and poses a threat to all aerobic marine life, as well as to people who depend on marine life for nutrition or livelihood.
Human activities have significant impact on coral reefs. Coral reefs are dying around the world. Damaging activities include coral mining, pollution, overfishing, blast fishing, the digging of canals and access into islands and bays. Other threats include disease, destructive fishing practices and warming oceans. The ocean's role as a carbon dioxide sink, atmospheric changes, ultraviolet light, ocean acidification, viruses, impacts of dust storms carrying agents to far-flung reefs, pollutants, algal blooms are some of the factors that affect coral reefs. Evidently, coral reefs are threatened well beyond coastal areas. Climate change, such as global warming, causes a rise in ocean temperatures that lead to coral bleaching which can be fatal to the corals.
Living Oceans Society is a Canadian environmental organization that has been a leader in the effort to protect Canada's oceans since 1998. It is based in Sointula, British Columbia, with a satellite office in Vancouver, British Columbia. Living Oceans Society's vision states that: Canada's oceans are sustainably managed and thriving with abundant sea life that supports vibrant and resilient communities.
The following outline is provided as an overview of and topical guide to fisheries:
Among the effects of climate change on oceans are an increase of ocean temperatures, more frequent marine heatwaves, ocean acidification, a rise in sea levels, sea ice decline, increased ocean stratification, reductions in oxygen levels, changes to ocean currents including a weakening of the Atlantic meridional overturning circulation. All these changes have knock-on effects which disturb marine ecosystems. The primary factor causing these changes is the Earth warming due to human-caused emissions of greenhouse gases, such as carbon dioxide and methane. This leads inevitably to ocean warming, because the ocean is taking up most of the additional heat in the climate system. The ocean absorbs some of the extra carbon dioxide in the atmosphere and this causes the pH value of the ocean to drop. It is estimated that the ocean absorbs about 25% of all human-caused CO2 emissions.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
Saltwater fish, also called marine fish or sea fish, are fish that live in seawater. Saltwater fish can swim and live alone or in a large group called a school.
Climate change in Guam encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. territory of Guam.
The poleward migration of coral species refers to the phenomenon brought on by rising sea temperatures, wherein corals are colonising cooler climates in an attempt to circumvent coral bleaching, rising sea levels and ocean acidification. In the age of Anthropocene, the changing global climate has disrupted fundamental natural processes and brought about observable changes in the submarine sphere. Whilst coral reefs are bleaching in tropical areas like the Great Barrier Reef, even more striking, and perhaps more alarming; is the growth of tropical coral species in temperate regions, which has taken place over the past decade. Coral reefs are frequently compared to the "canaries in the coal mine," who were used by miners as an indicator of air quality. In much the same way, "coral reefs are sensitive to environmental changes that could damage other habitats in the future," meaning they will be the first to visually exhibit the true implications of global warming on the natural world.
Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.
Climate change in Fiji is an exceptionally pressing issue for the country - as an island nation, Fiji is particularly vulnerable to rising sea levels, coastal erosion and extreme weather. These changes, along with temperature rise, will displace Fijian communities and will prove disruptive to the national economy - tourism, agriculture and fisheries, the largest contributors to the nation's GDP, will be severely impacted by climate change causing increases in poverty and food insecurity. As a party to both the Kyoto Protocol and the Paris Climate Agreement, Fiji hopes to achieve net-zero emissions by 2050 which, along with national policies, will help to mitigate the impacts of climate change.
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