Development of the Escape Response in Xyrauchen Texanus: Do Razorback Suckers have Poor Escape Performance?

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

The escape response is a reflexive behavior that allows fish to swim rapidly away from predators. This behavior is believed to be particularly important for larval fishes, which are contstantly preyed upon by other fish and invertebrates. In fact, it is thought that the main reason many species of native fish are currently disappearing from the Colorado River is that their larvae are consumed by introduced fish species. Thus, escape responses performance may be of critical importance in the continued survival of native fish species. This project will examine the development of the the escape response in the larvae of a native fish species, the razorback sucker (Xyrauchen texanus). In addition, escape response performance of another fish with benthic larvae, the rainbow trout (Oncorhynchus mykiss), will also be measured during development and compared to the performance of the razorback sucker. Rainbow trout provide an interesting ecological comparison with the razorback sucker for several reasons: (1) they are not native to the Colorado River, but currently live there in large numbers, (2) their larvae can survive in habitats with other predatory fishes, and (3) they are known to prey on young razorback suckers as adults. For both species, the development of the musculoskeletal and the nervous systems will be quantified to determine their potential contributions to escape response performance. Finally, two experimental temperatures will be used in this study to assess the role of recent temperature changes in the Colorado River on escape response performance, and to allow direct comparisons of the data colleted in these studies with data collected previously for other teleosts.