no fishermen out there??

Not a fisherman, Bren, but if you're in Shanzu, head for the top end of the beach, outside the Paradise Beach hotel and ask for Mohammed - he runs boat trips, he's a diamond bloke and should be able to help you out.
I think there is also fishing available from the marina at Mtwapa (right at the other end of Shanzu) - talk to the guy in the scuba hut