Is Mobility a Fixed Trait? Summer Movement Patterns of Catostomids using PIT Telemetry

<p>Fish populations are composed of a mixture of sedentary and mobile individuals, but it is not clear whether movement behavior is plastic or fixed for individuals and what proportion of the population exhibits mobile behavior. To investigate the mobility and movement patterns of two common species of suckers, the Sonora Sucker <i>Catostomus insignis</i> and the Desert Sucker <i>Catostomus clarkii</i>, in the Gila River of western New Mexico, we tracked 449 individuals over three summers using passive integrated transponder (PIT) telemetry. Both species were mobile and the typical linear home ranges for mobile individuals exceeded 150 m, but approximately 25% of individuals were detected only in a single habitat segment. We observed increased movement after spates caused by summer monsoon rains, and fish used areas of the stream differently under high- and low-flow conditions. Fish moved farther between years than within years, but a subset of individuals were found in the same locations from year to year. For the study species, movement behavior does not appear to be a fixed trait for individuals, and many individuals exhibited both stationary and mobile behavior among years. We also investigated whether sample size biased the estimates of movement parameters. We concluded that movement parameters would be underestimated by 20–50% if we had tracked fewer individuals, but the degree to which the parameters were biased varied from year to year.</p> <p>Received August 7, 2013; accepted January 23, 2014