Climate change is already affecting inland
fish across North America -- including some fish that are popular with anglers.
Scientists are seeing a variety of changes in
how inland fish reproduce, grow and where they can live, according to four new
studies published today in a special issue of Fisheries magazine https://fisheries.org/books-journals/fisheries-2/.
Fish that have the most documented risk
include those living in arid environments and coldwater species such as sockeye
salmon, lake trout, walleye, and prey fish that larger species depend on for
Climate change can cause suboptimal habitat
for some fish; warmer water, for example, can stress coldwater fish. When
stressed, fish tend to eat less and grow less. For other fish, climate change
is creating more suitable habitat; smallmouth bass populations, for example,
These changes will have direct implications -
some good, some bad - for recreational fishers, who, in the United States
alone, contributed nearly $700 million in revenue to state agencies through
license, tag, stamp, and permit purchases in 2015. Annually, anglers spend
about $25 billion on trips, gear, and equipment related to recreational fishing
in U.S. freshwaters.
"The U.S. Geological Survey and partners
are working to provide a fuller and more comprehensive picture of climate
change impacts on North American fish for managers, scientists, and the public
alike," said Abigail Lynch, a lead author and fisheries biologist with the
USGS National Climate Change and Wildlife Science Center.
The authors reviewed 31 studies across North
America and Canada that document fish responses to climate change. The
manuscripts describe the impacts of climate change to individual fish,
populations, recreational fishers, and fisheries managers.
One of the takeaway messages is that climate
change effects on fish are rarely straightforward, and they affect warmwater
and coldwater fish differently.
"Thanks to this synthesis, we can see the
effects of climate change on inland fish are no longer just future speculation,
but today's facts, with real economic, social, and ecological impacts,"
said Doug Austen, Executive Director of the American Fisheries Society and
publisher of Fisheries magazine. "Now that trends are being revealed, we
can start to tease apart the various stressors on inland fish and invest in
conservation and research where these programs will really make a difference in
both the short and long term."
The authors emphasize that resource managers
can take many actions to help sustain resilient fish communities and fisheries.
"Even though climate change can seem
overwhelming, fisheries managers have the tools to develop adaptation
strategies to conserve and maintain fish populations," said Craig Paukert,
a lead author and fisheries scientist at the USGS Missouri Cooperative Fish and
Wildlife Research Unit at the University of Missouri.
Smallmouth bass provide one example of how
climate change presents fisheries managers with both challenges and
Smallmouth bass, a popular recreational
species, are expanding their range northward with climate change. This
expansion can disrupt existing food webs but it also creates new prospects for
Because many recreational fishers want to
catch smallmouth bass, managers may need new management techniques to
accommodate the increased fishing demand while still maintaining the native
coldwater fish communities.
Consequently, said Paukert, the management
process may likely be an exercise in managing expectations of the stakeholders
for fisheries changing with climate change.
Other major findings:
-- Climate change may be altering abundance and
growth of some North American inland fishes, particularly coldwater fish such
as sockeye salmon, a species experiencing well-documented shifts in range,
abundance, migration, growth, and reproduction.
-- Climate change may be causing earlier
migration timing and allowing species that never occurred together previously
to hybridize. For example, native westslope cutthroat trout in the Rocky
Mountains are now hybridizing with rainbow trout, a non-native species.
-- Shifts in species' ranges are already
changing the kinds of fish in a specific water body, resulting in new species
interactions and altered predator-prey dynamics. For example, in Canada,
smallmouth bass have expanded their range, altering existing food chains
because the species compete against other top predators for habitat and prey
-- Droughts are forecasted to increase in
frequency and severity in many parts of North America, especially in arid
rivers. Such droughts exacerbate the impacts of water flow regulation in ways
that affect people, fish, and aquatic systems.
"The current state of the science shows
that climate change is impacting fish in lakes, rivers, and streams, but
knowing that is just the first step in effectively addressing the changes to
these important natural resources and the communities which depend upon
them," Lynch said.
The following papers are available in
Fisheries magazine, published by the American Fisheries Society:
-- Physiological basis of climate change
impacts on North American inland fishes, authored by James E. Whitney
(Pittsburg State University), Robert Al-Chokhachy (USGS), Bo Bunnell (USGS) and
-- Climate change effects on North American
inland fish populations and assemblages, authored by Abigail J. Lynch (USGS),
Bonnie J. E. Myers (USGS), Cindy Chu (Ontario Ministry of Natural Resources and
Forestry; OMNRF) and others.
-- Identifying alternate pathways for climate
change to impact inland recreational fishers, authored by Len M. Hunt (OMNRF),
Eli P. Fenichel (Yale University), David C. Fulton (USGS) and others.
-- Adapting inland fisheries management to a
changing climate, authored by Craig P. Paukert (USGS), Bob A. Glazer (Florida
Fish and Wildlife Conservation Commission), Gretchen J. A. Hansen (Minnesota
Department of Natural Resources) and others.
This research was supported by the USGS
NCCWSC, which collaborates with universities, resource management
organizations, tribes and other partners to provide unbiased scientific data
and tools that contribute to an understanding of the widespread impacts of
climate change on fish, wildlife, ecosystems, and people.
The eight Climate Science Centers, managed by
NCCWSC, form a national network and are regionally distributed to address the local
needs of resource managers and decision makers. CSC research projects cover a
wide array of climate change-related impacts, including sea-level rise, extreme
storms, increased wildfire patterns, invasive species, glacier loss, and