By Eric Freedman
Inland fisheries are important indicators of changes in ecosystems from things such as hydropower projects and deforestation. Image: Ken Bosma
Inland fisheries and aquaculture account for more than 40 percent of the world’s reported fish production but their harvest is frequently under-reported and ignored in the Great Lakes region and elsewhere, a new study says.
“The central role of inland fish in aquatic ecosystems makes them good indicators of ecosystem change,” said the study by scientists at Michigan State University, the U.S. Geological Survey, Carleton University in Canada and the University of Hull in the United Kingdom.
Ecosystem change includes threats from agriculture, hydropower projects and deforestation, as well as overfishing and invasive species.
Although the study focused primarily on inland fisheries in the developing world, it also addressed the situation in the Great Lakes and the region’s inland waters.
“Fish respond directly to some environmental stressors such as toxic and thermal pollution, flow change and climate change,” according to the first global review of the value of inland fisheries and fish.
The study cited “massive die-offs” of alewives in Lake Michigan in the 1960s, an occurrence that “brought to public and political attention large ecological changes occurring in the Great Lakes.”
It identified 10 reasons why inland fisheries are important globally, starting with food security and economic security.
Lead author Abigail Lynch of the Geological Survey said the importance of inland fisheries “is sometimes masked in areas in the Great Lakes where there are surely people who are fishing for subsistence.”
The high profile of larger-scale recreational and commercial fisheries may hide the importance of “these invisible fisheries,” said Lynch, who works for the federal agency’s National Climate Change and Wildlife Science Center.
Co-author Steven Cooke, a Carleton University fish ecologist, said the study points out that there are “multiple dimensions of fisheries. It’s not just one thing for one group. It’s many things for many groups, especially in the North American context.”
Culture matters too, including tribal culture, Cooke said.
Lynch said, “When you think of all the places where fish are culturally important, often those cultures have a strong connection with the land and the waters.”
Other benefits of inland fisheries include empowerment of people in low-income nations, recreational services, human health and biodiversity, the study said.
Co-author William Taylor, a fisheries and wildlife professor at MSU, said many Great Lakes Basin fisheries provide food for low-income people.
The study identified “knowledge transfer” as reflected in exchanges of information and sharing of management successes between scientists and resource managers in the U.S.-Canadian Great Lakes and the African Great Lakes.
Taylor said that transferred knowledge includes “what happened with the collapse of the commercial fisheries” in the U.S.-Canadian Great Lakes, as well as the “resurgence of the walleye and lake trout with different food webs, and all the lessons we’ve learned about invasives and how to mitigate the impact of things like lampreys.”
The study described inland fisheries as “aquatic canaries in the coal mine” that can warn of current and potential adverse environmental impacts.
Taylor said, “Nobody planned for alewife in the Erie Canal and sea lamprey coming through the Welland Canal. It signaled system collapse. Changes in the food web were giving us a warning that things were not good.
“When discussing land, municipal water, shipping, hydropower, fish will tell you how healthy the ecosystems are,” he said. “It’s giving fish a voice at the table. To me, they’ve always been the sentinel organism.”