Inshore anglers have all seen redfish school up in tight groups and hide out in the shallowest water they can find. It's more common in the winter time when most other fish have left the inshore waters, leaving dolphin without other alternatives for food. 

This video by youtube user "captainchad2007" shows in great detail how shallow the redfish get, and the method which the dolphin uses to catch them. After picking off a redfish, the mother dolphin retreats to deeper water and shares her catch with her calves, then returns for another morsel.

After a few fruitful trips between the redfish school and her calves, she brings her young ones in, demonstrates her fishing technique, then allows them to practice on the school of fish.