Seasonal migration patterns and site fidelity of adult paddlefish in Lake Francis Case, Missouri River

摘要

We used ultrasonic telemetry to determine the distribution, seasonal migration patterns, and site fidelity of adult paddlefish Polyodon spathula in a main-stem Missouri River impoundment. Thirty-two adult paddlefish collected from two different spring congregation areas in Lake Francis Case, South Dakota. were surgically implanted with ultrasonic tags and relocated monthly from March to November 1994-1996. Paddlefish tagged in the Big Bend tailwaters were captured in this area and in another possible spring congregation (the White River) during pre-spawning and spawning periods, whereas paddlefish tagged in the White River were never located in the Big Bend tailwaters or in areas above the White River. Male and female paddlefish used reservoir habitats similarly except during the pre-spawning period, when male paddlefish used the White River more than would be expected by chance and all females implanted at the White River site remained below the White River. In both the postspawning and winter periods, all paddlefish moved downstream and congregated in the lower reservoir reaches. Up to 62% of males and 36% of females returned to their original capture site during the presumed spawning period at least 1 of the 2 years after tagging, Thirty-one percent of mates at large for 2 years returned to their initial spring capture location each of the following years, but only 9% of females returned. Our results indicate that some paddlefish exhibited site fidelity to the areas where they were captured (i.e., the White River) and presumably attempted to spawn. although winter distribution was similar among all tagged paddlefish. Restoration and stocking efforts may need to focus on habitat management at the locations where paddlefish may spawn, given adequate substrate.