The June sucker, Chasmistes liorus, is very narrowly distributed, occurring naturally in Utah Lake and the Provo River, and nowhere else in the world. Although the species was once abundant in Utah Lake, it is now extremely rare. Major causes of the June sucker's decline include flow alterations, pollution, drought, hybridization with other sucker species, and competition with and predation from exotic fish species. The June sucker is Federally listed as endangered, and efforts to help recover the June sucker population are on-going.
Interestingly, although June suckers are members of the sucker family, they are not bottom feeders. The jaw structure of the June sucker allows the species to feed on zooplankton in the middle of the water column.
June sucker adults leave Utah Lake and swim up the Provo River to spawn in June of each year. Spawning occurs in shallow riffles over gravel or rock substrate. Fertilized eggs sink to the stream bottom, where they hatch in about four days. No parental care is given to eggs or young.