A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z
Ocean
Continuous body of saltwater covering the majority of the earth’s surface, geographically divided into the Pacific, Atlantic, Indian, Southern and Arctic oceans.
Ocean acidification
The ongoing decrease in the pH of the world’s oceans attributed to excess human-induced carbon dioxide emissions.
Ocean current
Continuous steady movement of ocean water in a prevailing direction and defined area.
Oceanic
A term used in connection with the open ocean water beyond the edge of the continetal shelf. In this documentm the oceanic ecosystem zone represents the sea water area deeper than approximately 200 metres.
Oceanic Trench
Long but narrow topographic depressions of the sea floor. They are the deepest parts of the ocean floor.
OCS
See Offshore Constitutional Settlement
Offshore
Waters extending from inshore to the continental shelf (approx 200m). Offshore waters are considered by the Australian and New Zealand Environment and Conservation and Council to mean the area of the Exclusive Economic Zone extending from the border of the three nautical mile State and Territory waters to the limit of Australia’s international marine boundary, i.e. 200 nautical miles. In a more general sense, the term ‘offshore’ refers to the waters beyond the inshore waters (see ‘inshore’).
Offshore Constitutional Settlement
Arrangement commenced in 1982 whereby State and Commonwealth Governments can introduce legislation on a fishery-by-fishery basis, passing responsibility for control to one or the other administration. Fisheries for which OCS arrangements are not in place may be managed as status quo fisheries or through joint control. See Offshore Constitutional Settlement 1995 (Fisheries Management Paper No. 77).
Offshore waters
Tend to be more oceanic (open) waters, though may still relate to outer Continental shelf waters.
Oligochaetes
A group of worms. Most live in freshwater or terrestrial habitats, but some are marine.
Omnivore
An animal that feeds on both animal and plant matter.
Open access fishery
‘Open access’ is a colloquialism used to describe those fisheries or fishing activities (within the total number of licensed fishing boats in WA’s overall fishery) for which there are no restrictions on the number of vessels with access or on the use of specific types or quantities of fishing gear by those boats.
Operculum
Any covering flaps or lid-like structures in organisms, such as the gill cover in many fishes.
Opportunistic
Taking of food as it becomes available.
Orbit
The curved path of an object in space as it revolves around another object.
Organic matter
Plant and animal residues, or substances made by living organisms.
Organism
A living creature.
Ornamental fish
A term used for fish commonly seen in the aquarium industry.
Osteichthyes
A class of fish having a skeleton composed of bone.
Otolith
Fish ear bone.
Otter trawl
Demersal trawl operated by a single vessel in which the horizontal opening of the net is achieved and maintained by angle-towed otter boards (large rectangular ‘boards’ of timber or steel) and the vertical opening by a combination of floats on the headrope and weights on the ground line. Attached between the head and ground ropes and the towing warps, the otter boards are spread apart by the hydrodynamic forces acting on them when the net is towed.
Outcompete
To be more successful than other organisms in obtaining access to the same limited resources.
Outer core
(Of the Earth) is a liquid layer about 2,266 kilometres thick composed of iron and nickel which lies above the Earth's solid inner core and below its mantle. Its outer boundary lies 2,890 km (1,800 mi) beneath the Earth's surface. The transition between the inner core and outer core is located approximately 5,150 km beneath the Earth's surface. The temperature of the outer core ranges from 4400 °C in the outer regions to 6100 °C near the inner core.
Output controls
Controls directly limiting a catch such e.g. bag limits, quotas, area catches.
Overfishing
Fishing beyond sustainable levels.
Oviduct
The passage between the ovaries and the outside of the body in egg-laying animals.
Oviparous
The young hatch from eggs, laid externally to the mother’s body.
Ovoviviparous
The young develops internally from eggs and are retained in the female until hatching occurs. The offspring are born ‘live’.