Dispersal and Life History Traits of Notropis girardi (Cypriniformes: Cyprinidae), Introduced into the Pecos River, New Mexico

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Abstract
The Arkansas River shiner Notropis girardi was introduced into the Pecos River, New Mexico, in 1978 and was common in collections made in 1986-1987. From collections made since 1978 in the Pecos River drainage, we analyzed patterns of dispersal and abundance, and compared life history traits with a native population of N. girardi from Revuelto Creek, New Mexico. Notropis girardi dispersed downstream, presumably from a single introduction, colonizing much of the mainstream Pecos River (260 km) by 1981. Since 1981, the distribution and abundance of introduced N. girardi has expanded slightly. Age structure, growth and mortality rates of the Pecos River population are similar to those reported in the literature and to a native population of N. girardi in New Mexico. Timing of reproduction was similar for non-native and native populations, and both may exhibit multiple spawning peaks. Notropis girardi reproduction in the Pecos River coincided with large increases in flow. High discharge presumably initiates spawning and promotes downstream dispersal. Similarity of flow regimes of the Pecos River to those formerly found in lotic systems in the native range of N. girardi (e.g., Cimarron River, Kansas and Oklahoma) may account for the relative success of this introduced population.