Pelagic Fish - Oceanic Fish

Oceanic Fish

Oceanic fish (also called open ocean or offshore fish) live in the waters that are not above the continental shelf. Oceanic fish can be contrasted with coastal fish, who do live above the continental shelf. However, the two types are not mutually exclusive, since there are no firm boundaries between coastal and ocean regions, and many epipelagic fish move between coastal and oceanic waters, particularly in different stages in their life cycle.

Oceanic epipelagic fish can be true residents, partial residents, or accidental residents. True residents live their entire life in the open ocean. Only a few species are true residents, such as tuna, billfish, flying fish, sauries, commercial pilotfish and remoras, dolphin, ocean sharks and ocean sunfish. Most of these species migrate back and forth across open oceans, rarely venturing over continental shelves. Some true residents associate with drifting jellyfish or seaweeds.

Partial residents occur in three groups: species which live in the zone only when they are juveniles (drifting with jellyfish and seaweeds); species which live in the zone only when they are adults (salmon, flying fish, dolphin and whale sharks); and deep water species which make nightly migrations up into the surface waters (such as the lanternfish). Accidental residents occur occasionally when adults and juveniles of species from other environments are carried by accident into the zone by currents.

• The huge ocean sunfish, a true resident of the ocean epipelagic zone, sometimes drifts with the current, eating jellyfish

• The giant whale shark, another resident of the ocean epipelagic zone, filter feeds on plankton, and periodically dives deep into the mesopelagic zone.

• Lanternfish are partial residents of the ocean epipelagic zone. During the day they hide in deep waters, but at night they migrate up to surface waters to feed.