Skip to main content
U.S. flag

An official website of the United States government

Fifth National Climate Assessment - Read the Report

Marine Species Distribution

This indicator examines changes in the location of fish, shellfish, and other marine species along U.S. coasts.

The graphs show the annual change in latitude (top panel; movement in miles) and depth (middle panel; change in feet) of 64 marine species in the eastern Bering Sea, 53 along the northeastern U.S. coast, and 63 along the southeastern U.S. coast.

The graphs show the annual change in latitude (top panel; movement in miles) and depth (middle panel; change in feet) of 64 marine species in the eastern Bering Sea, 53 along the northeastern U.S. coast, and 63 along the southeastern U.S. coast. Changes in the centers of biomass have been aggregated across all species by region. For each region, the change in latitude and change in depth are set at zero for a base year, 1989. The maps (bottom panels) show the annual centers of biomass for three species (walleye pollock, snow crab, and Pacific halibut) in the eastern Bering Sea from 1982 to 2019 (left), for three species (American lobster, red hake, and black sea bass) along the northeastern U.S. coast from 1973 to 2019 (center), and for three species (smooth butterfly ray, banded drum, and Atlantic croaker) along the southeastern U.S. coast from 1989 to 2019. Dots are shaded from light to dark to show change over time. Data source: NOAA Fisheries.

Date Range: 1973 - 2019

Marine Species Are Moving to Cooler Waters

Changes in water temperature can affect the environments where fish, shellfish, and other marine species live. Certain fish species naturally migrate in response to seasonal temperature changes, moving northward or deeper—to cooler waters—in the summer and migrating back during the winter. As climate change causes the oceans to become warmer year-round, however, populations of some species adapt by shifting away from areas that have become too warm. Along U.S. coasts, observations indicate that marine species are shifting northward or to deeper waters that have a more suitable temperature. As smaller prey species relocate their habitats, larger predator species may follow them.

Why It's Important

  • Marine species are a particularly good indicator of warming oceans because they are sensitive to climate and because they have been studied and tracked for many years.

  • Marine fisheries and fishing communities are at high risk from climate-driven changes in the distribution, timing, and productivity of fishery-related species.

  • Fisheries management that incorporates climate knowledge can help reduce impacts, promote resilience, and increase the value of marine resources in the face of changing ocean conditions.

About Marine Species Distribution

This indicator tracks marine animal species based on their “center of biomass,” which is a point that represents the center of each species’ distribution by total biomass (or weight) in terms of their geographic location (i.e., latitude, longitude, and depth). If a fish population were to shift generally northward, the center of biomass would shift northward as well. Fish are especially mobile, and thus tend to shift their location more easily than species on land because they face fewer physical barriers. Also, many marine species, especially fish, do not have fixed nesting places or dwellings that might otherwise compel them to stay in one place.

Data for this indicator were collected by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service (NOAA NMFS), who monitor marine species populations by conducting annual surveys in which they trawl the ocean at regular intervals along the coast. By recording what they catch at each location, scientists can calculate each species’ center of biomass. These data have been processed and made publicly available by Rutgers University at: https://oceanadapt.rutgers.edu.

This indicator focuses on two survey regions that have the most continuous and longest-running sampling: the Atlantic Ocean off the northeastern U.S. coast and the eastern Bering Sea off the coast of Alaska. The upper graphs show the average change in the center of biomass across 140 species in these regions. Tracking data from many species is useful, because if a change in behavior or distribution occurs across a large range of species, it is more likely the result of a more systematic or common cause. For consistency, these data are limited to species that were identified every year. The lower maps show these changes geographically for three species in each region. These species were chosen because they represent a variety of habitats and species types (a mixture of fish and shellfish) and because they tend to be fairly abundant. Some of these species support major fisheries that are presumed not to be heavily impacted by overfishing, reducing the chance that fishing is unduly influencing the observed trends. Additional detail related to this indicator can be found as part of the U.S. Environmental Protection Agency’s Marine Species Distribution indicator.

Key takeaways from this indicator:

  • The average center of biomass of marine fish and invertebrate species in three U.S. coastal regions have generally shifted northward between 1989 and 2019. 

  • In the eastern Bering Sea, walleye pollock, snow crab, and Pacific halibut have generally shifted away from the coast since the early 1980s and moved northward by an average of 42 miles.

  • In waters off the northeastern United States, several economically important species have shifted northward since the early 1970s. The three species shown in the map (American lobster, red hake, and black sea bass) have moved northward by an average of 137 miles.

  • In waters off the southeastern United States, several species have shifted northward since the late 1980s. The three species shown in the map (Atlantic croaker, banded drum, and smooth butterfly ray) have moved northward by an average of 165 miles.

Water temperature is not the only factor that can cause marine animal populations to shift. Interactions with other species, harvesting, ocean circulation patterns, habitat change, and species’ ability to disperse and adapt can also influence marine populations. As a result, species might have moved northward for reasons other than, or in addition to, changing sea temperatures.