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Fisheries and climate change

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Rising ocean temperatures and ocean acidification are radically altering marine aquatic ecosystems, while freshwater ecosystems are being impacted by changes in water temperature, water flow, and fish habitat loss. Climate change is modifying fish distribution and productivity of marine and freshwater species. These changes have impacts on the sustainability of fisheries and aquaculture, the livelihoods of 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 and 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.

Impact on fishing communities[edit]

Coastal populations and fishing populations are dependent on fisheries and are particularly vulnerable to climate change. Low-lying countries such as the Maldives 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. 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. These impacts significantly impact sustainibility and subsistence practices.

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. 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. 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.

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.

Human activities increase the impact of climate change. Human activity has been linked to lake nutrition levels, where high levels of human activity 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, aqautic communities, and even birds. Lake Annecy, Lake Geneva, and Lake Bourget were subject to experiments related to their zooplankton. 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.

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.

Impact on fish production[edit]

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’. As a result, the distribution, productivity, and species composition of global fish production is changing, generating complex and inter-related impacts 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. 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.

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.

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. 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. 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. This movement of copepods could have large impacts on many systems, especially high trophic level fish. 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.

Fisheries and Climate Change Citation Addition:

Over-fishing[edit]

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. 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.

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. 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. 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.