By Eric Freedman
Capital News Service
LANSING — What happens when saving a small number of plants or animals in a species at high risk of extinction may harm many more common species?
That’s a real problem as conservation experts and public land agencies in the Great Lakes region wrestle with how to allocate scarce funds for habitat protection.
“Conservation practitioners face difficult choices in apportioning limited resources between rare species to ensure their existence and common species to ensure their abundance and ecosystem contributions,” according to a new study by scientists from the Nature Conservancy’s Michigan chapter, the University of Wisconsin-Madison, Cornell University and the University of Oklahoma.
Their conclusion reflects the results of research about 35 species of native migratory fish in the 1,833 largest tributaries of the Great Lakes.
The study produced “rarity ratings” that found the white sucker to be the most abundant of those 35 species and the river darter the least common.
Co-author Patrick Doran, an ecologist and state conservation director for the Nature Conservancy, said there’s lots of money spent on endangered species, “but that’s limiting. The key for us here is the clear recognition of what you choose to invest in, and that there are tradeoffs. As soon as you start focusing on a single species, you’re making tradeoffs.”
Consider such well-known and iconic species in peril in the Great Lakes region as the endangered Kirtland’s warbler, endangered piping plover and threatened sturgeon. While government programs and efforts by nonprofit organizations have helped them survive, those efforts provide only “isolated or local value for other species,” Doran said.
Some, like the sturgeon, also have cultural significance.
Now consider white suckers, a less-known, less-glamorous and much more common native fish found in the region.
Common critters like white suckers can offer what scientists call “ecosystem services” provided by nature, Doran said. Such services include clean air, clean water through filtration, soil formation, habitat and climate regulation.
According to the Michigan Department of Natural Resources, “suckers are among the first fish to attract attention in the spring as they begin their upriver spawning runs, often before the ice is off of inland lakes. Anglers line the banks, fishing the bottom in the deep holes below riffles with earthworms. Suckers can be found in virtually all the state’s rivers, including most trout streams.”
Doran said white suckers deliver good nutrients to streams and play a major role in the ecosystem by bringing food – themselves – to predators farther up the food chain.
Making trade-offs in natural resource management is nothing new, Doran said, pointing to “conflicts between game and non-game species at a state level in terms of the money and effort put into management.”
He said, “States often have to cater to game species (deer, bass, salmon) with their public service responsibility, when it could be argued that these efforts do relatively little for the natural system.” As an example, he said government may spend its money on producing fish in hatcheries instead of habitat restoration in large lakes and streams.
As for fish, the new study’s “commonness-rarity spectrum” said white suckers were found in far more of the 1,833 tributaries —54 percent — than the next three runner-ups: yellow perch, longnose dace and brook trout. The endangered river darter, found in only nine tributaries, was followed in rarity by the threatened mooneye and the endangered channel darter.
Historically, the river darter lived in the Cass and Au Sable rivers in Saginaw and Iosco counties and close to the shore of Saginaw Bay in Huron and Tuscola counties, according to the Michigan Natural Features Inventory. It was last found in the Lake Erie drainage from the Huron River in 1941 in Monroe County.
Earlier this year, Ontario adopted a river darter recovery strategy for the southwestern part of the province in the Lake St. Clair drainage area.
“In this area, the species is rare and has only been collected 29 times in small and large rivers and Lake St. Clair since first discovered in southwestern Ontario in 1973,” the Ministry of Natural Resources and Forestry’s strategy said. “The main threats to these populations are likely physical and chemical habitat alterations and invasive species.”
It said, “Based on the limited number of individuals caught since 1973, the species is likely currently in low abundance and may require population enhancement and/or reintroduction to maintain self-sustaining, viable populations.”
The study, published in the journal “Global Change Biology,” said, “Given that common species worldwide are declining more rapidly than rare ones in major groups, our findings provide incentive for triage among multiple worthy conservation targets.”
Doran said, “They’re both highly worthwhile to conserve and protect and maintain. Which are you going to choose to invest in? There’s not an answer to that.”