At a glance, what's there not to like about milder winters and warmer waters for northern waters?
"Smallmouth bass, a popular recreational species, are expanding their range northward with climate change," said the U.S. Geological Survey (USGS), in reporting on findings that it compiled from reviewing 31 studies across the U.S. and Canada that document fish responses to climate change.
But, it cautioned, "one of the takeaway messages is that climate change effects on fish are rarely straightforward, and they affect warmwater and coldwater fish differently."
For example, an expanding smallmouth population will result in new species interactions and altered predator-prey dynamics. That will complicate life even more for coldwater fish species already stressed by milder conditions. Thus, managers will be tasked with both accommodating the desires of anglers who want to catch bass and maintaining native species.
That means managing not only the fish but "the expectations of the stakeholders for fisheries changing with climate change," said USGS.
Fish most at risk are those living in arid environments and coldwater species, including walleye and trout, as well as prey species that these larger fish depend on for food. "Climate change can cause suboptimal habitat for some fish," the agency said. "Warmer water, for example, can stress coldwater fish. When stressed, fish tend to eat less and grow less."
Other climate change consequences:
- Increased frequency and severity of droughts, especially in arid areas, will exacerbate the impacts of regulations on water flow and use for fish and aquatic systems, as well as people.
- Altered migration times for some coldwater species will allow species that never spawned together before to hybridize. Native westslope cutthroat trout in the Rocky Mountains already are hybridizing with rainbow trout, a non-native species.
- Abundance and growth of some coldwater species will be reduced. Changes in range, abundance, migration, growth, and reproduction already are occurring for sockeye salmon.
“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.
“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,” added Doug Austen, Executive Director of the American Fisheries Society.
“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.”