On a particularly hot July day during the summer of 2012, Phil Cochran, Gary Borash, and I were netting fish in the backwaters and side channels of the Mississippi River in southwestern Wisconsin. We were working for the Wisconsin Department of Natural Resources on an annual survey of Asian carp, a group of four non-native species from China that threaten Wisconsin’s aquatic ecosystems (see also “An Upstream Battle” in Wisconsin People & Ideas, Summer 2010).
Asian carp became established in the Mississippi River in Arkansas in the late 1970s and have gradually spread to southern and central Illinois, where they have the potential to displace several commercially and recreationally important native fishes. While a few stray Asian carp adults have been found in the Mississippi River and its tributaries in Wisconsin, we were searching for evidence that the invasive fish was reproducing, which would mean that it might be able to establish a self-sustaining population here.
During the netting I noted that in one spot the river registered an astonishing 94 degrees—the warmest water temperature I’ve ever observed or even heard of in the state. It was the only time I could recall in my over forty years of Wisconsin fish studies that I felt like getting out of the water to cool off. All three of us were close to heat exhaustion by the time we finally got back to the Eagles Roost Resort in Cassville to catch some rest before going out again the next morning.
While we did not collect any juvenile Asian carp that day, we did capture and release a few pallid shiners, a native minnow species on the Wisconsin Endangered Species List. A species is officially considered “endangered” in Wisconsin if it is extremely rare and likely to disappear from the state without strict protection. Collection and harvest are prohibited, and human activities with the potential to affect the species receive close scrutiny and may be blocked or allowed to proceed only with modifications.
When I told one of the resort workers about the absence of Asian carp from our nets, he was relieved. However, when I told him about the endangered shiners we saw, he cocked an eyebrow. “Why do we need to protect those fish?” he asked. “What good are they?” Maybe it was the heat, but I couldn’t come up with a good answer and the conversation moved to other topics.
However, his question stayed with me as I headed back to my room for a blissfully cool shower and a cold beer. As a lifelong, self-professed fish obsessive, I’ve always believed that all fish species are worthy of study and protection. It never occurred to me to ask why we have laws to protect rare fishes—or rare species of any animal or plant—in Wisconsin if that species is common elsewhere and in no danger of disappearing across its entire range. It seems that arguments for protecting these locally rare plants and animals are not as well developed or easily explained as those for globally rare species, which are in trouble everywhere they occur.
• • • • •
Many wild plants and animals have clear economic value, making it is easy to argue for their protection, or, more accurately, their conservation or “wise use” in order to ensure a steady supply and a consistent economic return. Think of the cod we eat at a Friday fish fry, the bears we travel to Yellowstone National Park to see, or the wild ginseng some diligently search for and sell at a high price. In Wisconsin, fish species such as the muskellunge and largemouth bass are carefully monitored and managed as they are pursued by hundreds of thousands of anglers who contribute millions of dollars to the state’s economy and support thousands of jobs. Other species popular with anglers such as channel catfish and lake whitefish are also harvested commercially for food.
Many wild plants and animals, sometimes termed non-game species, have no significant direct use yet may support other highly valued species or play a critical ecosystem role. Sometimes it’s both, as with the small fishes upon which musky and bass prey that often consume mosquito, black fly, and other nuisance insect larvae.
Some organisms of little obvious value may have unusual metabolic processes or pharmacological properties that perhaps someday could be transformed into profitable chemicals or helpful drugs. For example, the blood of lampreys—six species of which occur in Wisconsin—contains a compound that may help improve the delivery and uptake of drugs used to treat human brain disorders. Likewise, the venom produced in the spines of some fishes has the potential for pharmaceutical applications (three small catfishes with venomous spines live in Wisconsin).
Even if we don’t fully explore the economic, ecological, or pharmacological value of a species, it still has intrinsic value. As Aldo Leopold eloquently states in A Sand County Almanac, when talking of wildlife conservation and ecosystem management: “To keep every cog and wheel is the first precaution of intelligent tinkering.” And many people believe (as do I) that humans have a moral obligation as stewards of the Earth to ensure the survival of species, each a unique and amazing product of evolution (or, if you prefer, God’s creation).
Ironically, rules designed to preserve rare species (which typically prevent them from being caught and kept) can limit our exploration of their chemical or pharmacological value. To capture and experiment on rare Wisconsin species requires special permits from the WDNR that are issued only for sanctioned scientific or educational purposes. Overtly commercial permit applications are likely to be rejected, discouraging exploration into a species’ economic possibilities. Thus, the slender madtom, a small catfish, is unlikely to have the venom in its spines analyzed for possible pharmacological properties in Wisconsin, where it is very rare. But such an analysis certainly could be done in southern Illinois or Missouri, where it is common and not specifically regulated.
Because of their scarcity, most rare species in Wisconsin are also unlikely to play a key role in supporting economically important species or factor much into ecosystem function. Even the moral argument for preserving locally rare species doesn’t hold much water. It’s difficult to make a simple and compelling moral case for preserving a species here if many viable and secure populations remain elsewhere. The pallid shiners we caught in 2012 and 19 other Wisconsin fish species fall into this category. If pallid shiners were to be lost from Wisconsin, the species would be in no immediate danger of disappearing from the Earth. Or would it?
• • • • •
The overall likelihood of a species continuing to survive is enhanced when it consists of a variety of populations spread out across the landscape. Small populations geographically removed from the core of the species’ range, as is the case for most locally rare species in Wisconsin, provide an extra margin of safety for the species’ survival.
Excessive harvest is often what we think of as a primary driver of species decline, but disease epidemics triggered by ecosystem alteration and loss of habitat due to unfettered development can potentially eliminate even abundant species over a few decades. Too, harmful invasive species can place additional pressure on native plants and animals, accelerating their decline. Yet it is humans, as the May 2019 United Nations report on biodiversity notes, that largely control the fate of the nearly one million species at risk of extinction over the next few decades.
Indeed, a quick glance at the last two centuries of biodiversity in America underscores how quickly formerly common plants and animals can decline and even disappear in the face of human activity. In the 1800s, for example, there were an estimated 60 million American bison; a century later only about 300 remained, the last vestiges of a species decimated by unrestricted hunting and the agricultural transformation of the landscape. Similarly, at the time Europeans first began settling North America, there were thought to be three to five billion passenger pigeons, representing 25% to 40% of all the birds in what is now the United States. By 1900 the species was extinct, done in by wildly excessive hunting and massive losses of native forests, prairies, and wetlands.
The presence of a protected population, even if small, that exists beyond a species’ core range is a relatively inexpensive form of biological “insurance.” As the human population and its ecological footprint continue to grow, this insurance will likely become increasingly important. For example, the expansion of Asian carp in the central United States threatens the paddlefish and several other native large-river fishes. If Asian carp do not become established in Wisconsin, then Wisconsin may become an important refuge for the paddlefish and other large river species.
Locally rare populations also provide another kind of survival insurance. These populations typically exist in marginal areas, either geographically or ecologically, where conditions are extreme relative to those at the core of its range. Consequently, these marginal populations may have developed unique genetic, ecological, or behavioral traits that allow them to survive less-than-optimal conditions. They represent a potential reservoir of adaptations that may allow the species to persist in the face of a changing global environment. Just as a diverse financial portfolio is best in times of economic change and uncertainty, so too is a species that has distinct populations with different environmental tolerances and preferences. A population in Wisconsin, although small and under threat, may confer increased resilience for the species as a whole.
For example, one of the climate shifts observed over the last 30 years has been an increase in annual temperature fluctuations. Overall, most areas are projected to become warmer in the future, but they will also likely encounter more extreme warm and cold conditions. Populations at the northern edge of a species distribution, such as the pallid shiner in Wisconsin, already experience a wider range of temperatures than populations farther south. The Wisconsin population of pallid shiners can tolerate water up to at least 94 degrees, as our 2012 sampling demonstrated, and wintertime temperatures as cold as 32 degrees. This means they have a total tolerance range of at least 62 degrees. More southerly populations in Louisiana, Texas, and Mississippi, where the water temperature never gets below 40 or so degrees, have a tolerance range of only about 52 degrees. Thus, Wisconsin’s pallid shiners may be better equipped to deal with an increasingly variable and extreme temperature regime than their southern counterparts. And if the southern edge of pallid shiners’ range were to become too warm for the species, the population in Wisconsin would become even more important to the overall survival of the species.
• • • • •
So what good are those few pallid shiners we caught on that hot summer day? Perhaps not much individually. But their presence in our stretch of the Mississippi may have disproportionate importance because of their geographic location and genetic, ecological, and behavioral adaptations. The same probably is true of many other rare plants and animals in Wisconsin. Preserving as many wild species and as much diversity as possible within these species is an economic and moral benefit to humankind. Consequently, the treatment these species receive in our state through strict and specific laws may ultimately help determine their continued survival on earth.
But laws alone are not sufficient. We all have a role and a responsibility to help preserve the plants and animals of the state. We must advocate and work for healthy air, water, and soil, appropriate land use, protection from invasive species, intact and properly functioning ecosystems, and responsible use of energy and natural resources to help ensure the continued well being of all Wisconsin species—ourselves included.