. >> reporter: so secret says aden martin that we know little about great white sharks.e don't know how many there are or how long they live. we have never seen them mate or give birth. >> fantastic. look at that. such an enormous guy gets so far out of the water. >> it is essentially profile and sacrificed mobility for speed. it is like having a truck running on the bicycle current. >> for it is a remarkable sight. seals are their favorite food. >> oh! that was fantastic. it came out upside down. >> we are next to seal island here. population 50,000. when you see a shark coming for the seal, who are you rooting for? >> i root for the seals. >> this man is a shark tourism operator. >> i think we can relate to the situation of the seals. they are at home, sitting in the sun, happy, safe, having a wonderful time and everything is great but when they get hungry, they have to go out in the street and in the street there are a lot of rough characters. >> it is a catch 22. unfortunately for the seals they need to go out and feed. at this island they have a good chance of being