NISSWA, Minn. — It was a Sisyphean task. Between each of the 30-odd races, the Turtle Wranglers rushed to the center of the circular track in the parking lot to collect 20 tired reptiles, then haul replacements out in buckets for the next heat. By the time they finished refilling the starters’ buckets with enough water for the turtles to splash around in, the next race was already over, and it was back to the track to swap them out.