The bike follows your eyes, so look at the escape route, not the canoe. Map a clean line around the left of the blockade in your mind. Now for a little countersteering demonstration: Push the handlebar forward with your left hand, shift your weight to the left and bingo!--you turn left. After clearing the unexpected inconvenience, push right, lean right and turn right, theoretically ending up back on your original trajectory. Meanwhile, go easy on the brakes and throttle. Your brain and tires are very busy, and it's easy to overwhelm either or both.