Diel Cover use and Local Site Fidelity of a Large Southwestern Cyprinid, Bonytail Gila elegans, in a Lower Colorado River Backwater

摘要

Sonic transmitters were affixed to 10 large (40.4-51.4 cm TL) adult bonytail Gila elegans in 2003 from Cibola High Levee Pond, a small, isolated backwater adjacent to the lower Colorado River in Arizona and California, Point and paired directional observations showed that all marked adult bonytail occupied interstices of large riprap during daytime and used open water areas during darkness, presumably to feed. There were 2 spatial patterns of nighttime distribution by adult fish; 70% of fish exhibited mesohabitat site fidelity to a particular area of the pond, while others appeared to move about at random. Selection or design of bonytail management areas including grow-out and refuge sites should consider cover requirements for larger fish, as this may be a limiting factor if lack of cover subjects some individuals to higher predation risk.