Mr Milk said..
I'm no fish expert, but I can make a story on why feeding might come on around dusk.
The various small things that live in shallow water and hide away during the day come out at dusk. Little fish start eating them and bigger fish eat them in turn. At the top of the chain is the shark. Same scenario would operate on very cloudy days. Low light levels bring out the organisms at the bottom of the food chain.
Pretty close Mr Milk. Essentially the change of light period has a flow on effect from the tiniest morsels, as this all has to do with their less advanced eyes which simply struggle to adjust to the changing conditions. This snow balls rapidly, and the food chain broadens. It amazes me that the entire dawn / dusk feeding period all anglers wait for is triggered by less advanced eye sight. So essentially its about opportunity. Either way, that 2 hour period either side of dawn and dusk is prime feeding time- whether you're a enthusiastic sardine eating plankton, or a great white.
Sure, sharks feed when they want, but their far more likely- and successful- at dawn and dusk.
