Neosho madtom (Noturus placidus)

Neosho madtom
Conservation status
	; Near Threatened (IUCN 3.1)
	; Threatened (ESA)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Siluriformes
Family:	Ictaluridae
Genus:	Noturus
Species:	N. placidus
Binomial name
	Noturus placidus; W. R. Taylor, 1969

The Neosho madtom (Noturus placidus) is a small North American freshwater catfish, endemic to areas of Kansas, Missouri, and Oklahoma. It was first documented in the Spring River, Kansas, in 1963 and the species was first properly described by W. R. Taylor in 1969.^[2]

The Neosho madtom has features characteristic of all North American catfish, though it varies in size and colored markings when compared to similar catfish species in the same region. The species has a brownish midline stripe and an overall mottled appearance. The Neosho madtom’s prefered habitat consists of shallow, flowing streams called riffles. The species reproduces at the head of these riffles where the gravel bottom is coarse. Individuals emerge from the sandy riffle bottom at night to feed on aquatic insects including mayflies.^[2]

Since the Neosho Madtom relies heavily on watershed ecosystems in the Kansas region, human activity in this area has negatively impacted the species. The species was listed as Vulnerable in 1986, and has maintained a Near Threatened IUCN status in the United States since 1996.^[3] Currently, construction and habitat degradation in the Cottonwood River Basin is monitored in an attempt to recover the species.^[4]

Description

Physical Characteristics

Since the Neosho madtom is a member of the North American catfish family, it has a physical appearance typical of the catfish, including mouth sensory feeders (called barbels), smooth scaleless skin, and a dorsal fin.^[2] Because of these physical similarities, the Neosho madtom is often grouped with its catfish relatives that live in close proximity in the Neosho Basin. Three of these related species are the stonecat, the slender madtom, and the brindled madtom. The species can be distinctly identified by its characteristic dorsal adipose fin which is attached to the upper back of the fish and has a light colored ridge. While the dark pigment on the adipose fin of the brindled madtom reaches the ridge, the pigment on the Neosho madtom adipose fin stops short of the rim. Additionally, unlike its closely related species, the Neosho madtom has a mottled skin pigmentation and is roughly half the size of the slender madtom. Adult Neosho madtom are typically less than 75 mm (3 in) in length, which is similar to that of the brindled and slender madtom.

Distribution - Historical and Present Range

The Neosho madtom is found in the Neosho, Cottonwood, Spring, and Illinois Rivers in Kansas, Missouri, and Oklahoma (for range map see^[3]). ^[2]^[5]^[6] The largest populations of the Neosho madtom are found in the stretch of the Neosho River from southeastern Kansas to 5 miles south of the Kansas-Oklahoma line, and in the Cottonwood River, from Chase County to its junction with the Neosho River in Lyon County, Kansas. ^[5]^[3] The fish persists less densely in the Oklahoma stretch of the Neosho River.^[3]

Historically, the Neosho madtom was also abundant in the Spring River, located in parts of Missouri and Kansas.^[6] While the species still survives at extremely low population densities in these areas, human construction has resulted in the limited distribution of the species. ^[6]

Habitat

Neosho madtoms inhabit gravel riffles in shallow streams with loosely packed gravel or sand bottoms, covered with leaf litter and debris. The gravel is typically 0.5 to 2.5 inches in diameter, although the fish have been occasionally observed in habitats with larger stone or cobble bottoms. Specifically, adults tend to prefer shallow riffles (less than 3 ft deep) with stronger currents (1-4 ft/s), while young Neosho madtoms prefer deeper, slower moving water. There is no federally designated critical habitat for the species. ^[2]

Behavior and Life History

Historical and Present Population Size

The Neosho madtom population fluctuates seasonally and annually. The current population size is estimated to be 1,000-10,000 individuals.^[3] Data from Moss and the Natural Science Research Associates estimate that there are three Neosho madtoms per 100 square meters.^[2] The estimated current abundance of the species in Missouri remains the same as the estimated historical abundance, but the Neosho madtom population in Oklahoma and Kansas has shown a decline. The species is currently present in roughly ⅔ of its historical distribution.^[3]

Research shows that populations of Neosho madtoms in the Neosho and Cottonwood Rivers remain large enough to maintain sufficient genetic variation if breeding between different riffle populations continues to occur. Interriffle breeding likely occurs because of annual water level fluctuations in the Neosho River and may also occur during drought.^[2]

Reproduction

Neosho madtoms are short-lived fish, only occasionally surviving more than three years. March marks the beginning of the Neosho madtom’s reproductive cycle, with spawning occurring in June and July. Although their reproductive habits have not been closely observed, Neosho madtoms are thought to nest in cavities within the gravel riffles, similar to other Noturus species.^[2] In closely related species, eggs are laid under small stones and are guarded by a parent. Research suggests that Neosho madtoms spawn at the crest or head of gravel bars where large cobble is abundant.^[7] Paternal guarding of eggs and broods has been observed. The male Neosho madtom cares for the eggs by fanning, rubbing and hovering over the eggs.^[8] Young madtoms have been recorded in the quiet waters below riffles.^[2]

Diet

The Neosho madtom feeds on readily available aquatic insects, the most common being the larvae of caddisflies, mayflies, dipterans, and midges.^[2] Adults bury themselves in the gravel during the day and come out at night to search for food, normally within the first three hours after sunset. Larvae have been observed eating recently hatched brine shrimp and chironomid larvae.^[8]

Threats and Human Impact

Extensive habitat loss due to the creation of reservoirs in Kansas, Missouri, and Oklahoma was the central threat to the Neosho Madtom at the time of its ESA listing.^[2] Over the past century, an estimated one-third of the habitat of the Neosho madtom has been degraded due to anthropogenic impacts. At the time of listing, the creation of dams were of major detriment to the species. Dams in the following locations were highlighted as detrimental to the Neosho madtom: Lake o’ the Cherokees, Lake Hudson, Fort Gibson Reservoir, Tenkiller Reservoir in Oklahoma, John Redmond Reservoir on the Neosho River, and eighteen additional dams on the Neosho and Cottonwood rivers.^[2] The creation of dams disturbs gravel riffles and increases siltation, which limits the ability of the Neosho Madtom to burrow. It may also decrease the number of immature insects in the water, which the species relies on for food. Dams also reduce peak instream flows, which disturbs the shallow water conditions favored by the Neosho madtom.^[4] After the species’ listing in 1990, there have not been any further dams constructed in the habitat of the Neosho madtom. The removal of gravel bars for gravel mining and the diversion of water for the construction of roads and bridges has also contributed to habitat loss and possible fragmentation.^[2]

More recently, efforts to restore the riparian environment within the range of the Neosho madtom were identified as potentially disruptive to the species’ habitat.^[4] The Upper Neosho River Basin Stream and Riparian Restoration Project was proposed in 2009 to control erosion along 3.5 miles of the Neosho River. Alterations to the original plans were made in order to decrease potential damage to the species’ habitat. It was concluded that this project would likely not be harmful to the species. However, no further documentation reporting the effects of the project on the species is available.

In addition to direct habitat degradation, mining activity, feedlot operations, intensive row-cropping, and construction has increased water pollution. A study conducted in 2000 on the Spring River concluded that populations of the Neosho madtom are likely limited by contamination of their habitat and food sources due to nearby mining activities.^[9] Elevated levels of cadmium, lead, and zinc, and a variety of other chemicals, were found in this environment. However, a majority of the Neosho madtom’s populations within the Spring River are upstream from these polluting sites. High levels of these chemicals are known to affect reproductive behavior and weaken immune responses in fish. The researchers concluded that these effects were likely a limiting factor on the population growth of the species.

Status and Conservation

History of Listing under the Endangered Species Act

The Neosho madtom was listed under the Endangered Species Act on May 22, 1990, as Threatened wherever found.^[2] The species has maintained this listing status under the ESA, due primarily to extensive habitat degradation as a result of anthropogenic activities. Detrimental human activity includes the creation of dams, channelization, water pollution from mining and feedlot operations, alteration to the riparian environment for flood control and the creation of bridges and roads, and the direct removal of gravel riffles for gravel mining.

Two 5-Year Reviews have been conducted by the U.S. Fish and Wildlife Service since the initial listing, with the first released on March 25, 2013. The most recent 5-year review of the species was initiated on August 10, 2018 and was released February 11, 2020.^[10] The status remained as “Threatened” and was assigned the priority number 8c, indicating that the species is under moderate threat and is thought to have a high potential for recovery. The reviewers conducted occurrence surveys in Kansas from 2016 to 2019 and found that the species continues to persist in small numbers in the locations previously recorded. The highest number of individuals recorded at a given site was ten. These surveys also offered the new information that the species continues to exist in the main stem of the Neosho River. The Review concluded that no change was needed to the status of the species, as low population numbers and continued threats suggests that the species is still in danger of becoming endangered. The 5-Year Review recommended six future actions to be taken to protect the species: consult with U.S. Army Corps of Engineers on dam operations, develop a population genetics study for the species, draft a new recovery plan, monitor the species, coordinate with local agencies and landowners regarding the removal of low-head dams, and reduce pollution through legislation and incentive programs.^[10]

History of IUCN Listing

The species was assigned the IUCN status of Vulnerable in 1986.^[3] This status was changed to Lower Risk/Near Threatened in 1996 and has maintained this status as of its last assessment on April 18, 2012. Despite continued habitat degradation, the status was altered because 1) the Neosho madtom is found in more than 10 locations, 2) likely has a population size exceeding 10,000 and 3) has not experienced a population decline of more than 30% in the last 10 years.

Conservation Effort

According to the 5-Year Review released in 2020, the Peoria tribe is currently working on captive propagation of the species as a method to increase population numbers.^[10] The possibility of captive propagation has also been discussed by Neosho National Fish Hatchery in Missouri, but it is not yet clear whether this is a viable option to recover the species. The USFWS reports no Conservation Plans for this species. Regulation measures have been taken to limit the impact of drainage structures in the Cottonwood River. Watershed development in South Fork now must be approved by the Kansas Department of Wildlife and Parks before the plans can be released.^[9] While population numbers remain steady, the actions recommended in the 2020 5-Year Review are necessary in order to increase population growth and recover the species.

References

^ NatureServe (2014). "Noturus placidus". IUCN Red List of Threatened Species. 2014: e.T14905A19032753. doi:10.2305/IUCN.UK.2014-3.RLTS.T14905A19032753.en.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ U.S. Fish and Wildlife Service. 1991. Neosho madtom recovery plan. U.S. Fish and Wildlife Service, Denver, Colorado. 42 pp.
^ ^a ^b ^c ^d ^e ^f ^g NatureServe 2014. Noturus placidus. The IUCN Red List of Threatened Species 2014: e.T14905A19032753. https://dx.doi.org/10.2305/IUCN.UK.2014-3.RLTS.T14905A19032753.en. Downloaded on 17 April 2020.
^ ^a ^b ^c U.S. Fish and Wildlife Service. 2010. “Upper Neosho River Basin Stream and Riparian Restoration Project.” Kansas Ecological Services Field Office, Manhattan, Kansas.
^ ^a ^b Bulger, A., & Edds, D. (2001). Population Structure and Habitat Use in Neosho Madtom (Noturus placidus). The Southwestern Naturalist, 46(1), 8-15. doi:10.2307/3672368
^ ^a ^b ^c Wilkinson, C., Edds, D., Dorlac, J., Wildhaber, M., Schmitt, C., & Allert, A. (1996). Neosho madtom distribution and abundance in the Spring River. The Southwestern Naturalist, 41(1), 78-81.
^ Pfingsten, D. G., & Edds, D. R. (1994). Reproductive Traits of the Neosho Madtom, Noturus placidus (Pisces: Ictaluridae). Transactions of the Kansas Academy of Science (1903-), 97(3/4), 82. doi: 10.2307/3627774
^ ^a ^b Bulger, A. G., Wilkinson, C. D., Edds, D. R., & Wildhaber, M. L. (2002). Breeding Behavior and Reproductive Life History of the Neosho Madtom, Noturus placidus (Teleostei: Ictaluridae). Transactions of the Kansas Academy of Science, 105(3 & 4), 106–124. doi: 10.1660/0022-8443(2002)105[0106:bbarlh]2.0.co;2
^ ^a ^b Wildhaber, M., Tabor, V., Mulher D., Powell, K., Sowa, S. (2000). Natural and Anthropogenic Influences on the Distribution of threatened Neosho Madtom in a Midwestern Warmwater Stream. Transactions of the American Fisheries Society. 129: 243-261.
^ ^a ^b ^c U.S. Fish and Wildlife Service. 2020. 5-Year Review for Neosho Madtom (Noturus placidus). Kansas Ecological Services Field Office, Manhattan, Kansas.