Zuni bluehead sucker Catostomus discobolus yarrowi
ESA status: candidate for listing
The Zuni bluehead sucker is a highly imperiled fish that numbers just a few hundred individuals, which exist in just a few stream segments in two small watersheds in New Mexico and Arizona. It has garnered a host of special designations—state listings, a federal sensitive species designation, and even tribal protections—but not the protection it needs most: “threatened” or “endangered” status under the federal Endangered Species Act.
The Zuni bluehead sucker is a small, slender fish with a bluish head, silvery tan to dark green back, and yellowish to silvery white sides and abdomen. The fish grows between 3.5 to 8 inches. Males exhibit a bright red band running laterally along each side during the spawning season. The fish uses stream reaches with clean, perennial water flowing over hard substrate, such as bedrock. It feeds primarily on algae it scrapes from rocks, rubble, and gravel on the streambed. It appears to avoid silt-laden habitat, such as beaver ponds, which represent poor or marginal habitat.
Also known as the Zuni mountain sucker, the Zuni bluehead sucker was once common in the Little Colorado and Zuni River drainages. Scientists postulate that this subspecies may be a prehistoric hybrid of the Rio Grande sucker (Catostomus plebeius) and bluehead sucker (Catostomus discobolus). Now genetic isolation may be affecting the fish. In addition to showing signs of potential inbreeding in New Mexico, recent research suggests that some populations in Arizona may be distinct from those in New Mexico.
The current range of the Zuni bluehead sucker has been reduced to less than 10 percent of its historic distribution. The fish is now restricted to three semi-isolated populations (totaling just 3 stream miles) in the upper Rio Nutria drainage in west-central New Mexico, and scattered areas along 27 miles of the Kinlichee (a.k.a. “Kin Li Chee”) watershed in Arizona. The fish continues to face a host of threats, including habitat modification and stream siltation caused by logging, livestock grazing, road construction, residential development and reservoirs; reduced or discontinuous stream flow from water withdrawal for irrigation; application of piscicides (fish toxicants); and competition with and predation by exotic fishes and crayfish.
The U.S. Fish and Wildlife Service first designated the Zuni bluehead sucker as a candidate for listing in 1985, then dropped the subspecies when it reorganized the candidate list in 1996, only to make the fish a candidate again in 2001. In the meantime, the states of New Mexico and Arizona have designated the sucker as “endangered” and “protected,” respectively. The U.S. Forest Service has made the fish a “sensitive species,” and the Zuni Pueblo has declared the sucker off limits for fishing. Unfortunately, none of these protections requires habitat conservation or improvement, which would be compelled by Endangered Species Act listing. WildEarth Guardians will continue pressing for federal listing for the Zuni bluehead sucker to give this rare fish a chance at survival.
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photo credit: New Mexico Department of Game and Fish