Identify Climate Impacts

In this step:

  • Enhance understanding of the climate impacts already occurring or expected to occur in the fishery system

Fishing boat in Normandy, France. Photo: © Alessandra Sarti/Alamy


Many stressors—some related to climate and some not—contribute to changes in fishery systems. As started in Step 1, it is essential to identify both climate and non-climate stressors that affect the fishery to inform decision-making about potential actions.

Examples of Stressors that Affect Fisheries
Examples of climate-driven stressors that affect marine fisheries include changes in physical factors such as temperature, ocean acidification, sea level rise, and ocean circulation. Climate change is also inducing more frequent and severe events such as storms, marine heatwaves, and harmful algal blooms. Non-climate stressors that affect fishery systems can include pollution, habitat loss and degradation, overfishing, increases in human conflict, natural disasters, poverty, food insecurity, and disease. The effects of non-climate stressors can also be exacerbated by climate change stressors, often compounding or intensifying the effects.

Together, climate and non-climate stressors can lead to major impacts on a fishery system, affecting fish stocks and catch, fishing operations, and communities that depend on them for livelihoods and well-being. Here we focus on some climate stressors and consider their potential direct and indirect impacts on the fishery system.

Examples of Climate Stressors and Impacts on Fishery Systems

Warming Ocean Temperatures

Warming ocean temperatures can lead to a variety of changes in marine ecosystems, including:

  • Changes in abundance of living marine resource stocks. As water temperatures warm due to climate change, they may create conditions that are more or less favorable for certain marine species. Increasing temperatures tend to be detrimental to species near the warm end of their geographic range, but may enhance productivity at the cool extent of the range. These effects can alter the success of fishing operations and influence the effectiveness of management measures.
  • Changes in species locations. Long-term changes in the geographic distribution of species reflect shifts in temperature, other physical ocean conditions, and prey availability. Some species move to track their preferred environmental conditions, including temperature. As species shift, fishing vessels may have to travel further to catch their target species, or they may no longer have access to the stock.
  • Increased pathogens. Warmer water temperatures can facilitate the spread of pathogens that affect seafood safety. For example, toxic strains of Vibrio bacteria increase in oysters under warmer water conditions, creating a risk of illness or even death from consuming raw shellfish. Such conditions threaten the health and well-being of seafood consumers as well as the economic viability of the fishery.
Marine Heatwaves

Marine heatwaves can cause abrupt changes in marine ecosystems and create shocks that can affect fishery operations and supply chains.

  • Coral bleaching. In severe cases, marine heatwave-induced coral bleaching events can change reefs from a coral-dominated state to an algal-dominated state, reducing habitat for particular reef fish species. This habitat change can alter fish community composition and reduce the abundance of species traditionally targeted in the fishery. Such changes can impact fishing incomes and food security.
  • Lethal effects. The extreme temperatures associated with marine heatwaves can result in direct mortality of some species, particularly sessile species living in the intertidal zone or shallow coastal waters. These species experience the greatest heat stress and are unable to move to cooler waters. Mortality events eliminate fishing opportunities for harvesters of those species and may affect nutrition and livelihoods in the community.
  • Altered fishery-ecosystem interactions. By altering where and when species occur in the ecosystem due to changes in suitable thermal habitat, marine heatwaves can change how fisheries interact with other species, including threatened and endangered species. For example, as humpback whales shifted their foraging grounds off California during a heatwave, whale entanglements in the Dungeness crab fishery increased, resulting in constricted fishing seasons.
Severe Weather Events

Severe weather events are increasing in frequency and severity as a result of climate change, creating impacts that include:

  • Risks to safety-at-sea. Increased storminess poses serious risks to fishing vessels, compromising the safety of fishers who are caught out in the storms or who choose to fish in marginal weather. Fishers who are most dependent on their catch for their food or income are more likely to risk fishing in storms, compromising their safety and lives to avoid hunger or debilitating economic hardships.
  • Reduced number of fishing days. To avoid risks to safety at sea, fishers may choose to stay in port on more days due to storms. In addition, large storms can destroy vessels or port facilities, without which fishing is not feasible. Both effects reduce the number of days fishers can be on the water, which has implications for income, livelihoods, and nutritional needs in some communities.
  • Disruptions to seafood supply chains. Large storms such as hurricanes and cyclones can destroy or severely damage infrastructure needed to transport, process, distribute, or sell seafood products. These effects can be felt over large geographies, with fisheries in one region of the world potentially being affected by storm-related supply chain disruptions in another region.

Information on how climate change may affect a particular fishery can come from a variety of sources, including local or traditional ecological knowledge and scientific observations or models. For instance, community elders are often aware of long-term changes in the marine ecosystem and fisheries, and may have insights into drivers or consequences of these changes. Additionally, fishers see changes on the water and may provide insights into changes that have occurred over seasons, years, or decades, as well as how these relate to climate cycles (e.g., El Niño) or environmental conditions. Scientific papers, reports, and model outputs also provide information on changes that have occurred or are projected to occur in a fishery. In some areas, global model outputs will be the only source of information about expected future changes, but in other locations, downscaled information tailored to the particular system may be available. Local scientists may be able to provide guidance on the best sources of information for a particular fishery.

While it is essential to know as much as possible about current and future impacts, it is also critical to recognize that there will always be unknowns. Climate models are not perfect representations of the real world. Human behaviors and policies affecting climate trajectories are likely to change in unanticipated ways, and more research is needed to fully understand the interactions that occur between climate and non-climate drivers. For these and other reasons, we can never have an exact prediction of what the future holds. Planning for climate-resilient fisheries means considering the unknowns and accounting for the uncertainties.

With this in mind, it is important to consider the changes that the fishery system is experiencing now and to draw on available research and tools to understand current and potential impacts, while also remaining aware that inevitable uncertainties exist. These considerations will help to determine how goals may need to be tailored to better account for and address changes in the system.

Some Sources of Climate Impact Information

Global Climate Models and Ecosystem Information

Downscaled Interpretations of Global Models

Biological and Fisheries Information

Traditional Knowledge

Case Study Examples

Dungeness crab supports California’s most lucrative commercial fishery and plays a critical role in the portfolio of species targeted by fishers. Unfortunately, over the last decade this fishery has experienced tremendous set-backs due to climate impacts. During the 2015-2016 fishing season, the fishery was shut down after a marine heatwave in the region led to an abnormally large and long-lasting, harmful algal bloom. As a result, crabs in the region absorbed a tremendous amount of biotoxins. While the crabs survived, these toxins posed serious health risks via human consumption.

To compound these disastrous impacts, the reopening of the season months later coincided with increased humpback whale abundance that had been exacerbated by the heatwave-driven compression of their foraging grounds. This overlap in fishing effort and whale migration led to an unprecedented number of whale entanglements in California. In subsequent years, the fishery faced reduced seasons to alleviate whale entanglement risk, costing the industry millions and severely impacting small-scale fishermen with limited resources to change target species.

As a result, a multi-stakeholder working group, inclusive of representatives from the fishing industry, was convened to inform an extensive and ongoing overhaul of California’s marine life risk management plan and to ultimately support the resilience of this fishery to future marine heatwaves.

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While many climate stressors have direct impacts on communities, some lead to other indirect and unexpected threats. For instance, in the Gulf of Maine, sea surface temperature has been warming three times faster than the global average for the past 40 years and the frequency of marine heatwaves has increased. This warming, in addition to long-standing conservation measures in the fishery, have supported increases in the abundance of the Maine lobster population.

However, during the 2012 marine heatwave, the fishery was substantially disrupted by an early start to the high-landings period. Lobsters moved into nearshore waters where they were caught by the fishery earlier than usual, and the supply chain was not prepared to handle the amount of lobster being landed so early in the season. The supply chain disruptions that occurred in the early season resulted in a price collapse – harming the livelihoods of many lobster fishermen in the U.S. and Canada.

Industry responses throughout the supply chain following the 2012 experience–such as improved handling practices, flexible trucking contracts, increased processing capacity, and expanded markets–have avoided similar outcomes during more recent marine heatwaves and have improved the resilience of the fishery system over the last decade.

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Located 670 km off the coast of Chile sit the Juan Fernandez Islands (JFIs), surrounded by an incredibly biodiverse marine ecosystem. The compilation of islands, reefs, and seamounts in the area has promoted strong ecosystem connectivity and has supported a high degree of marine and terrestrial endemism.

While many protections have been enacted to preserve the natural beauty and diversity of the JFIs and prevent overfishing and habitat degradation, impacts from climate change in congruence with other stressors pose serious threats to the surrounding ecosystems and communities. For many years, fishers in the JFIs had largely focused on a single species – lobster. However, communities are now realizing that this focus might be limiting their resilience, especially in the face of stressors such as El Niño Southern Oscillation (ENSO), tsunamis, and the recent global pandemic. For example, the 2010 tsunami resulted in an ecosystem shift exemplified by an outbreak of sea urchins, which the JFI communities are now working to consider as an independent profitable fishery in the region.

Diversification of the demersal fishery and development of the supply chain for sea urchins and other novel species is seen as an economic safety net, helping to confer socio-economic resilience.

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Tasks for Workbook

In the downloadable CRF Planning Tool workbook, complete these tasks on the Step 3 worksheet.

  1. List stressors and impacts that are being seen now
  2. List stressors and impacts that are expected to occur in the future
  3. Consider how these impacts may affect the ability to achieve fishery goals

CRF Planning Tool Steps