It Takes a Village to Adapt to Climate Change

By Kevin Bunch, IJC

ice-cover-lake-superior
Ice cover, like these slabs on Lake Superior, has been on a downward trend due to warmer winters since the 1970s, from a long-term average of 60 percent maximum coverage in 1975 to closer to 40 percent in 2015. This could lead to new climate challenges for communities looking to adapt. Credit: Sharon Mollerus

Climate change adaptation is a major challenge for the Great Lakes region, and researchers, officials and other leaders have been coming together to share experiences and ideas on how to prepare.

One hub of collaboration has been the Great Lakes Integrated Sciences + Assessments program (GLISA), which includes Michigan State University, the University of Michigan, the US National Oceanic and Atmospheric Administration’s integrated science and assessment programs, the Northeast Climate Science Center and the Midwest Regional Climate Center.

“There is a lot of really great work going on across the Great Lakes region at the state, local and regional levels,” said GLISA Program Manager Dr. Jenna Jorns. “What we need to move forward are … ongoing collaborations to draw on each other’s strengths and move all of our projects forward together.”

GLISA hosted a second biannual Great Lakes Adaptation Forum in 2016 to provide an opportunity for people to get together and share their work and strategies. The event included 150 registered attendees from the United States and Canada, representing universities, nonprofits, First Nations and tribal governments, federal agencies, and state and local officials.

Climate in the Great Lakes region has become warmer in recent decades, with relatively more of the warming during the cooler times of year, said GLISA Co-Director Jeff Andresen. While not all climate models agree on whether or not the region will get wetter or drier as a whole, he said most models suggest somewhat more annual precipitation in the future, with most of the additional precipitation coming during the winter months, and in extreme events. These conditions can impact water management, businesses and natural resources.

Since climate predictions and trends are a constantly moving target, he said it is trickier for infrastructure planners to know what to expect. Since those government officials have to plan for extended timeframes, a shifting climate introduces a new variable that’s harder to prepare for. For example, some communities in the Great Lakes region still use combined sewers that move storm water and wastewater through the same pipes. These pipes need to be built to withstand flows up to specific recurrence intervals – like a 50-year or 100-year storm – but due to climate change the pipes could see stronger storm events more frequently.

According to Alex Bryan, climate scientist and postdoctoral fellow with the Northeast Climate Science Center, the unique interaction between the Great Lakes and the atmosphere has its own effect on the region’s climate – as evidenced by “lake effect” snowfall. With shrinking ice cover due to warming temperatures, the warmer, more open waters could lead to an increase of lake effect precipitation, Bryan said – possibly in the form of lake effect rain.

While another Great Lakes Adaptation Forum isn’t happening until 2018, Bryan said the event is coordinated with the National Adaptation Forum, which will take place in Saint Paul, Minnesota, from May 9-11, 2017. In the meantime, lessons learned from the 2016 workshop are helping communities work together to locate resources and strengthen adaptation efforts in the United States and Canada.

Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.

Editor’s Note: This article was updated on March 30, 2017, to correct the dates of the National Adaptation Forum.

Rethinking Our Fisheries Management Strategy for Chinook Salmon

By Yu-Chun Kao
Research Associate
Department of Fisheries and Wildlife, Michigan State University
East Lansing, Michigan

chinook salmon joe nohner
A Chinook salmon. Credit: Joe Nohner

In a paper recently published in the journal Ecosystems, my co-authors and I showed that the current prey base in Lake Huron can no longer support the same level of Chinook salmon that prevailed in the 1980s. Consequently, we indicated that the good old days of Chinook salmon fisheries are gone and will never return.

Results from this study also implied that Chinook salmon fisheries in Lakes Michigan and Ontario will possibly follow the same fate, because several food web changes associated with the Chinook salmon collapse in Lake Huron have already occurred in these two lakes.

Maybe it is time to rethink whether fisheries management in the Great Lakes should be focused on stocked exotic species that anglers desire, like Chinook salmon, or native species such as lake trout and walleye that are better adapted to changing ecosystems.

Chinook salmon and other fish in the salmon family were introduced to the Great Lakes 50 years ago to create recreational fisheries. The intent was to turn alewives from a nuisance fish to a food source for salmon. Alewives reached a nuisance level of abundance around 1960 and drew public attention after their decaying bodies fouled beaches after several massive die-off events.

alewives sampling survey 2004
Alewives from a sampling survey in 2004. Credit: Tim O’Brien

 

Introduced salmon soon adapted to feed on alewives and successfully created multi-billion dollar fisheries.

Because salmon populations are artificially maintained or supplemented by hatchery stocking, the potential for predator–prey imbalance has been a concern for researchers since the early 1980s. Such an imbalance finally occurred in 2003 when the alewife population collapsed in Lake Huron.

However, the cause of this collapse is complicated. Since the late 1980s, prey fishes such as alewives and rainbow smelt had been experiencing increased predation pressure and a food shortage. Consumptive demands by salmon species first increased due to rises in stocking in the 1980s and then jumped sharply with natural reproduction of Chinook salmon in the 1990s. On the other hand, the production of algae at the base of lake food webs decreased because of feeding by invasive quagga mussels and reduction in nutrients after abatement programs initiated in the 1970s.

The year 2003 is unique in the ecological history of Lake Huron. It is the year when quagga mussels were first found, in significant amounts, in the deep part of the lake. It is also the year when there was a historical low of the nutrient inputs from agricultural and municipal sources. Since then, quagga mussels have been expanding while nutrient inputs have stayed at similar low levels.

While Chinook salmon fisheries collapsed in Lake Huron following the collapse of alewife population, estimates for sport angler harvests of Chinook salmon were close to a historical high in Lakes Michigan and Ontario during 2005–2008, despite increases in consumptive demand by salmon, expansion of quagga mussels, and a reduction in nutrients.

Nevertheless, according to our study, there is a clear warning signal for Chinook salmon fisheries in Lakes Michigan and Ontario. Chinook salmon have feed almost 100 percent on alewives in recent years.

Before the 21st century, Chinook salmon feed on both alewives and rainbow smelt. Rainbow smelt have continuously decreased since the 1990s because they are more vulnerable than alewives to food shortage caused by nutrient reduction and quagga mussel expansion. If the condition of Lake Huron after 2003 occurs in Lakes Michigan and Ontario, alewife populations in these two lakes will likely collapse, as well as Chinook salmon fisheries.

With ongoing changes in the Great Lakes, it will be more and more costly to maintain Chinook salmon fisheries. We have observed decreases in the alewife population and Chinook salmon harvests in Lake Michigan since 2010 despite the same, if not higher, level of managing efforts. On the other hand, harvests on native species like lake trout and walleye, which are better adapted to a food web without alewives, increased drastically in Lake Huron in recent years.

Now is the time, in my opinion, to rethink our fisheries management strategies for the Great Lakes.

alewives annual bottom trawl sampling
Alewife sampling during an annual bottom trawl survey. Credit: Tim O’Brien