Really?... And surely you slow down to 5 mph when deer (or kangaroos) are around. Is this going to be another Sailnet "those crazy racers" threads? If the immediate concern of a skipper is with catastrophic damage/holing/sinking and endangerment of the crew, then of course they're bound by duty to care more about the boat than the critter. We all put our immediate survival first. Any keel, yes, even on your boat, could injure a sea creature. By and large, hitting large things underway isn't good for either party. In my humble experience in boats large and small, I haven't met a sailor yet who's thought it was OK for either boat or beast to hit/be hit. It's just much too dangerous and outcomes much too unpredictable at any speed for any boat.
Now this guy probably didn't even know what happened:
And then there's this one: