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

Term	Meanings
Natural mortality	Deaths of fish from all causes except fishing. It is often expressed as a rate that indicates the percentage of fish dying in a year; e.g. a natural mortality rate of 0.2 implies that approximately 20 per cent of the population will die in a year from causes other than fishing.
Nautical mile	A unit of distance equivalent to one minute of the great circle of the Earth (= 1,852 metres).
NCP	National Competition Policy
NDS	National Docketing System
Non-endemic	Not native
NPOA	National Plan of Action for the Conservation and Management of Sharks
Oceanic	A term used in connection with the open ocean water beyond the edge of the continental shelf. In this document, the oceanic ecosystem zone represents the sea water area deeper than approximately 200 metres.
OCS	Offshore Constitutional Settlement
Offshore	Waters extending from inshore to the continental shelf (approx 200 m). Offshore waters are considered by the Australian and New Zealand Environment and Conservation 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).
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. For example, hand lining, drop lining, troll lining, and squid jigging are all methods associated with WA's open access or wetline fishery.
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.
Output controls	Management measures that directly limit the size of a fish catch (e.g. by quota); cf. input controls.
Overfished	Current fishing levels may not be sustainable, or yields may be higher in the long term, if the fishing level is reduced in the short term. This may be due either to growth overfishing or recruitment overfishing.

Derived from: Department of Fisheries publications; Fishery Status Reports. Resource Assessments of Australian Commonwealth Fisheries. 1998. Bureau of Resource Sciences, Department of Primary Industries and Energy, Canberra ACT; and Henderson's Dictionary of Biological Terms, published by Longman Scientific and Technical Press, 1989 (10th edition).