The discussion about sharks and Lake Nicaragua sent me scurrying for my
copy of "The Sharks of Lake Nicaragua" by Randy Wayne White, the
Florida adventure writer. (As I collect shells, so also do I collect
his work.)
In this book of various stories there is one chapter called "The
Sharks of Lake Nicaragua".   Could be interesting and informative
reading, since it refers to studies and perspectives on the fresh water
sharks by a Thomas Thorson.  Sadly from what I re-read, the marine
population in the lake is not thriving.

Karen

On Mar 29, 2008, at 5:16 AM, Andrew Grebneff wrote:

>> Lake Nicaragua is home to the only species of shark that inhabits
>> fresh water, the Bull Shark. And of all the sharks I have encountered
>> while diving, the Bull Shark is the most dangerous. A Bull Shark
>> attack recently took place in less than three feet of water, with the
>> shark propelling itself from deeper water almost on to land to attack
>> a person. So be careful when you're reaching into the water for that
>> really interesting snail! That, unfortunately, is my best tip.
>
> In fact sharks live well up both the Amazon and Ganges rivers, and no
> doubt many others. Their metabolism allows them to pass freely
> between salt and fresh waters. That isn't just the bull shark
> (Carcharias taurus) but others as well, including Carcharodon
> carcharias (though the latter must be a long way from home, as they
> are territorial inshore dwellers who live near seal colonies). I have
> heard that the Nicaragua and Ganges sharks are particularly hungry.
> The Amazon ones probably have plenty of fish, crocodilians and snakes
> to eat and so don't bother with queer-looking humans.
>
> Now, I have HEARD that Lago Nicaragua is full of marine taxa which
> have adapted to freshwater. But there appears to be no literature
> (not that I've done a Google search yet). OK, just Googled ... so
> much rubbish! Archeological stuff and sharks... cichlids collection
> catalogs... blogs... ... tourism and old expeditions... relationship
> between Iran and Lake Nicaragua... NOTHING on the molluscs
> themselves... AAARGH!! I would be most interested to see images of
> the molluscs, or exchange for specimens.
>

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