I concur with the Pentax Optio W30. I use mine for work as a consulting ecologist in the Florida wetlands. It is durable and takes great pics. It does not allow manual exposure settings but in most situations the different settings will get the job done well. Believe me you want a small camera to take a picture while controling the fish and protecting that expensive rod and reel you have saved up for.
An SLR is too bulky and heavy not to mention not waterproof without more cash and making it heavier and bulkier. I won't send this thread into a discussion about Nikon vs Cannon but both are excellent. I use a Nikon D100 and an F5 (film). Would like faster frames per second on the digital but to do so brings the cost way up. Some of the newer Nikons (D40) are cheaper and look promising (Look in the recent Outdoor Photographer magazine for a comparison of features. I think consumer reports has a recent article too).
And you thought deciding on a fly rod and reel was tough!