Petition to List the Rio Grande Sucker (Catostomus plebeius) Under the Endangered Species Act

James Whitney
Posted on: 7/18/2022 - Updated on: 8/10/2023

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Three of the cornerstone native fish of the Rio Grande—the Rio Grande cutthroat trout (Oncorhynchus clarki virginalis), Rio Grande chub (Gila pandora), and Rio Grande sucker—are all imperiled. These three species co-evolved to fill different niches in the Rio Grande and its tributaries. As dams, diversions, and human land uses including livestock grazing and timber harvest have altered the Rio Grande, these species have all declined and are now deemed imperiled. The Rio Grande cutthroat trout is currently a candidate for listing under the ESA, and has been since 2008. WildEarth Guardians petitioned the Rio Grande chub for listing in 2013. With this petition, we request that the Service also protect the Rio Grande sucker under the ESA.

The Rio Grande sucker occurs in the Rio Grande and its tributaries in southern Colorado, New Mexico, and several states in Mexico. Rio Grande sucker populations are declining, mainly due to habitat loss and degradation. Runoff and sediment loads from logging, large-scale agricultural practices, and livestock grazing, among other factors, have decreased habitat quantity and quality for the sucker. Diversion of water for agriculture reduces stream flows and destroys habitat. Dams and diversions are fragmenting populations. The sucker is also subjected to competition from introduced fish species, in particular the white sucker (Catostomus commersonii). Climate change is projected to exacerbate current threats as well as further tax the already-strained river. The state of Colorado recognized the precarious position of the Rio Grande sucker by listing it as “endangered” in 1993 and published a recovery plan for the species in 1994. Unfortunately, the state listing did not stem the species’ decline.

To ensure protection for the Rio Grande sucker, WildEarth Guardians seeks its listing as “threatened” or “endangered” under the ESA. Listing will afford the sucker critical habitat designation, a recovery plan, and the stringent federal protection it needs to survive. Designating the Rio Grande sucker as “endangered” or “threatened” would also benefit its remaining habitat, which is under threat from continued human uses of the land and water.


Petition to List the Rio Grande Sucker (Catostomus plebeius) Under the Endangered Species Act. (2014).….

Affiliated Organizations

WildEarth Guardians protects and restores wildlife, wild rivers, and wild places in the American West. We have four programs focusing on wildlifewild placeswild rivers, and climate and energy.

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