The plesiosaur theory presents several problems. first, the plesiosaur is an air breather. such a creature would need to surface often and, therefore, be seen more frequently. second, it's unlikely that the same creature has lived in the loch since the last ice age. today's creature would have to be the offspring of an original plesiosaur trapped long ago. this would suggest multiple creatures in the loch (needed to produce offspring). again, sightings would be more frequent if this were the case. what is the main purpose?