Read the book
Close to Shore. It is about the great white attacks off the Jersey shore in 1919. One attack occured in a freshwater river, some two miles from the ocean. The bull and the tiger shark are actually more aggresive towards man since they come into contact with man moe often than the great white. Any takers on where the breed ground for Atlnatic great whites are? Just off Montauk, Long Island, NY. That Gulf Stream heats the waters up for them, they can eat and and breed for months.
When I was living in Sydney, I remember the shark nets that line some of the nicest beaches down there. It the jellyfish don'tget you down there, the sharks seem to. Easy way to avoid shark attacks, ya know, don't go in the water.
From
http://www.wavescape.co.za/top_bar/tidings/Sharks/shark_KZN.html:
"The biggest Great White ever caught was a female of 6.4 meters, which was caught off Cuba in 1945. It weighed 3312 kilos and its girth reached 4.5 meters; several lorries were needed to tow and transport it. A 10 meter specimen is also said to have been captured, but neither photo nor expert account exists, only subjective statements. The record specimen are always female, since in the sharks, females have larger measurements than males."
There are pics on that site of a 1.6 tonne great white.