Status and conservation of native catostomids in the Lower Pecos River, New Mexico

Authors: Nikolas D. Zymonas, David L. Propst

Year: 2008 (xl)

Abstract

The native fish assemblage of the lower Pecos River drainage in New Mexico historically included four catostomids: river carpsucker Carpiodes carpio, blue sucker Cycleptus elongatus, smallmouth buffalo Ictiobus bubalus, and gray redhorse Moxostoma congestum. The lower Pecos constitutes the entire range of blue sucker and gray redhorse in New Mexico. All four species were common in various surveys prior to 2000, particularly from Malaga, NM upstream. More intensive investigations since 2000 have documented a dramatic decline of native fishes in this reach beginning in 2003 in association with toxic outbreaks of golden algae Prymnesium parvum. Blue sucker populations have been extirpated from the main stem Pecos River. A small population exists in the Black River, one of only two perennial tributaries to the lower Pecos in NM, although recruitment has not been documented. Gray redhorse is common in the Black River, but in the Pecos River persists only in a 10-km fragment below Carlsbad and near the confluence of the Black River. Recurring outbreaks of golden algae (e.g., October and November 2007) threaten remaining populations in the Pecos River. Smallmouth buffalo have not been collected in the Pecos since 2003. River carpsucker remains common in the lower Pecos River and upstream as well. In response to species declines, a golden algae monitoring program was started, and ways to lessen the likelihood and severity of toxic outbreaks are being explored. Captive propagation programs have been started for blue sucker and gray redhorse, and a formal State of New Mexico recovery planning process is underway.