By Dyani Sabin

The sole remnants of the Scioto madtom exist in ethanol-filled jars at a warehouse in Ohio. When removed, its pale body and dull bluish eyes resemble a ghostly figure rather than a formidable catfish.

In 2013, the International Union for Conservation of Nature labeled the Scioto madtom extinct, having not been spotted since 1957. However, the U.S. still categorizes this fish as endangered, despite the U.S. Fish and Wildlife Service's acknowledgment of its likely extinction. This situation places the madtom in a state of "extinction purgatory," caught between classification and reality.

While it may seem straightforward to declare a species extinct, the process is far more complex. Biologists cannot confirm extinction merely by failing to observe a species during surveys, which are often limited by funding. Recent research published in BioScience highlights that these surveys may not accurately reflect actual population trends. Many biologists believe that numerous species should be declared extinct yet remain on the endangered list. Concerns over habitat preservation and uncertainty about true extinction status complicate the situation further.

“It’s tricky because there are two competing things that are going on with keeping them on the endangered species list,” explains Easton White, a population biologist at the University of Vermont. “On one hand, you don’t want to mistakenly delist a species that still exists; but on the other, if you don’t remove extinct species from the list, it distorts the real extinction rate.”

Some scientists argue that it is time to acknowledge the extinction of the Scioto madtom and other similar species, directing efforts toward species that can still be preserved. Eben Paxton, a rare bird ecologist with the U.S. Geological Survey, notes that many Hawaiian birds, including the Kaua‘i ‘akialoa, are accepted as extinct by biologists but remain on the endangered list. He cautions that retaining extinct species on the list can divert attention from those truly in need of conservation.

The implications of delisting are significant. Declaring a species extinct can lead to the loss of protections for its habitat. This was evident in the case of the Myanmar Jerdon’s babbler, which was rediscovered in 2015 after being thought extinct for 74 years. This rediscovery triggered renewed conservation efforts, allowing local farmers in the Ayeyarwady Delta to adopt sustainable practices beneficial for both the bird and the community, according to Rob Tizard of the Wildlife Conservation Society in Myanmar. Such habitat protections not only aid individual species but can also rejuvenate entire ecosystems.

Angela Boyer from the Ohio branch of the U.S. Fish and Wildlife Service emphasizes the importance of ensuring that resources are not wasted on species that no longer exist. However, not all researchers agree. Some activists fear that species like the Scioto madtom might still be surviving in hidden locations. The exceedingly rare purple catspaw mussel was declared extinct in 1984 but was later rediscovered in Kilbuck’s Creek in Ohio. Kierán Suckling, executive director of the Center for Biological Diversity, expresses concern over prematurely declaring extinction. He identifies 86 species on the endangered list that share a similar fate as the Scioto madtom, with 62 likely extinct before their listing.

Suckling argues that keeping potentially extinct species on the Endangered Species List is a prudent choice, as it requires minimal funding and could make a difference if they are rediscovered in the future. “The cost to retain them is very low, and it offers significant conservation benefits,” he notes.

The only known Scioto madtoms are the eighteen specimens preserved at the Museum of Biological Diversity at Ohio State University, collected by biologist Milton Trautman between 1943 and 1957 in a specific location on Big Darby Creek. Despite his efforts, Trautman never identified the fish's nesting habitat and speculated that it may have inhabited different areas throughout the year.

Local scientists speculate about the madtom's disappearance, attributing it to habitat alterations and competition with other species. Marc Kibbey, Associate Curator of Fish Collection at the Ohio State Museum of Biological Diversity, states that significant changes to the burrows and banks of Big Darby Creek likely contributed to the fish's decline. Development along the river has made it prone to flooding and erosion.

According to Brian Zimmerman, a research associate at Ohio State University, the original area where the Scioto madtom was found is one of the least protected sections of Big Darby Creek, mostly comprised of private property. In contrast, the middle part of the river has strict protections due to other endangered species. Zimmerman observes that these protections have improved water quality, making the Scioto River the most biodiverse river in Ohio. He notes that when Trautman discovered the madtom, the creek was in dire condition, filled with runoff and sewage. “Many of the species that endured that period are thriving now,” he remarks. “If the madtom were still present, we would have found it by now. Many have searched for it over the past 60 years.”

One theory suggests that biologists may not be conducting sufficient surveys, though it is unclear what the optimal frequency would be. Easton White analyzed data from 822 species monitored for at least 35 years and determined that an average of 16 years of surveys is needed to accurately assess population changes. However, he acknowledges significant variability in this timeframe, complicating the use of simple rules.

The current IUCN guidelines suggest a 10-year or three-generation period for assessing species changes, but White argues that this may not be adequate. “It’s not just about the species or its generation time, but how much population variation occurs annually,” he explains. Each species requires individual modeling based on empirical data, and even with such evidence, confirming extinction remains a daunting challenge.

Paxton emphasizes that declaring extinction ultimately relies on judgment, as “you can’t prove an absence.” For species nearing extinction, quantifying remaining populations is a complex task. Researchers like Paxton have developed mathematical models to estimate whether surveys are overlooking endangered birds, incorporating factors like population density and survey duration. Although these models are comprehensive, they are also time-intensive, and the IUCN is working to adopt these methods in its assessments.

For now, the process for determining species status on the endangered list is lengthy and bureaucratic. It typically involves researchers collecting updated information every five years. If a species is deemed extinct, it enters a delisting work plan, where the Scioto madtom currently resides. The last dedicated search for the fish was in 1985, leading to its recommendation for delisting in 2009. At that time, the madtom was expected to receive a specific evaluation date within three years to confirm its extinction status.

Eleven years later, the U.S. Fish and Wildlife Service has yet to proceed with delisting. A reevaluation was scheduled for September 2019, and if determined extinct, a proposed rule for delisting would follow, accompanied by a public comment period and an official ruling a year later, potentially leading to formal extinction status in 2020. “People are very reluctant to give up hope,” Parham notes.

Even if delisted, there is an emergency re-listing process if the madtom is rediscovered, allowing for protective measures to prevent catastrophic outcomes. However, Suckling worries that once a species is removed from the list, re-listing may occur too slowly to avert its demise. He cites a report indicating that nearly half of species went extinct while awaiting endangered status. Although some species have been added to the list shortly after emergency petitions, none have returned after being delisted. For elusive species like the madtom, Suckling advocates a cautious approach to delisting. “All signs suggest we should err on the side of caution until extinction can be firmly established.”

Despite the consensus among researchers familiar with the Scioto madtom that it is likely gone, they still express a glimmer of hope. Zimmerman admits he has not specifically searched for the fish in recent years but continues to look during his collecting trips. The surprising aspect of the madtom's disappearance is that it was last found in one of Ohio's most protected streams.

Kibbey concurs, reflecting on the improved water quality in Big Darby Creek but acknowledges the uncertainty of not having searched for the madtom himself in several years. “Who knows, it might be time to look again!” he laughs.

Rare rediscoveries inspire scientists like Kibbey and Suckling to stay engaged and hopeful. Paxton believes that extinction declarations can also serve a vital public purpose, drawing attention to the broader challenges species face due to climate change and other global threats. “In conservation, we often seek positive narratives,” he says, and while extinction is not a cheerful subject, “highlighting it can become a rallying point.”

For the Scioto madtom, that moment may come, but for now, it remains a specter suspended in ethanol, awaiting its final verdict.