Ovoviviparous fish – Fish whose eggs are fertilized and hatched within the female’s body. The eggs are enclosed in separate membranes and the embryos within them receive no nourishment from the mother. Most sharks and rays are ovoviviparous.
Oviparous fish – Fish that lay eggs from which the young later hatch.
Overhead cast – The basic casting style where the rod is pulled straight over the head and the lead starts in the air.
Over-run – see Backlash
Outrigger – A pole device used when trolling to spread baits or lure out from the side of the boat.
Operculum – The plate which covers the gills.
Off the ground – A casting style where the terminal tackle is laid out on the beach with the lead straight out behind the angler prior to casting.