Abiotic factors affecting summer distribution and movement of male paddlefish, Polyodon spathula, in a prairie reservoir

Six male paddlefish, Polyodon spathula, were implanted with ultrasonic temp erature-sensing transmitters and tracked during June through August 1997 to quantify effects of physicochemical conditions on their distribution and m ovement in Keystone Reservoir, Oklahoma. Paddlefish moved about twice as mu ch during night than day. Movement rate of paddlefish was related to reserv oir water level, inflow, and discharge from the reservoir at night; however , none of these variables was significant during the day. Location in the r eservoir (distance from the dam) was negatively related to water level and positively related to inflow during day and night periods. Location in the reservoir was negatively related to discharge during the day. Paddlefish av oided the highest available water temperatures, but did not always avoid lo w dissolved oxygen concentrations. Paddlefish avoided the Cimarron River ar m of the reservoir in summer, possibly because of high salinity. Our study demonstrates that distribution of paddlefish during summer and movement in Keystone Reservoir was influenced by physicochemical and hydrologic conditi ons in the system. However, biotic factors (e.g., food availability) not me asured in this study may have been influenced by abiotic conditions in the reservoir.