Population Abundance and Sex Ratio of the Viviparous Freshwater Fish Poeciliopsis baenschi (Poeciliidae) Throughout its Range in Western Mexico

• Published in: Western North American naturalist Vol. 72; no. 3; pp. 357 - 368
• Main Authors: Zúñiga-Vega, J. Jaime, Hernández-Rosas, Ana L., Molina-Moctezuma, Alejandro, Pérez-Mendoza, Hibraim A., Rodríguez-Reyes, Fernanda R., Bravo-Espinosa, Yolotzin M., Espinosa-Pérez, Héctor
• Format: Journal Article
• Language: English
• Published: Provo Brigham Young University 01.11.2012; Western North American Naturalist
• Subjects: adults; Animal populations; Demographic aspects; Demography; Distribution; Ecological genetics; females; Fish; Fish populations; Freshwater; Freshwater ecology; freshwater fish; Freshwater fishes; Habitat (Ecology); Identification and classification; juveniles; males; Native species; Poeciliidae; Poeciliopsis; Population ecology; Population estimates; probability; Reproduction; Sex ratio; Sexes; Streams; Mexico
• ISSN: 1527-0904; 1944-8341
• DOI: 10.3398/064.072.0310

We estimated population abundance and sex ratio for a freshwater live-bearing fish species (Poeciliopsis baenschi) that inhabits fluvial systems in western Mexico. We conducted mark-recapture experiments in 6 distinct populations. We used both our catch data as well as estimates of capture probability to calculate the number of individuals per unit water volume for adult males, adult females, and juveniles. Overall, abundance varied among sites from 23.8 individuals · m-3 to 363.2 individuals · m-3. In most of our study sites, the estimated sex ratio was markedly biased toward females (up to 11 females per male). We discuss the potential causes and implications of the observed demographic features.