Canadian fisheries waters: all waters in the fishing zones of Canada, all waters in the territorial sea of Canada and all internal waters of Canada (Fisheries Act, sec. 2).

Compensation (for loss of habitat): replacement of natural habitat, increase in the productivity of existing habitat, or maintenance of fish production by artificial means in circumstances dictated by social and economic conditions, where mitigation techniques and other measures are not adequate to maintain habitats for Canada's fisheries resources.

Conservation of habitats: the planned management of human activities that might affect fish habitats to prevent destruction and subsequent loss of fisheries benefits.

Destruction of fish habitat: any permanent change of fish habitat which completely eliminates its capacity to support one or more life processes of fish.

Disruption of fish habitat: any change to fish habitat occurring for a limited period, which reduces its capacity to support one or more life processes of fish.

Fish: includes parts of fish, shellfish, crustaceans, marine animals and any parts of shellfish, crustaceans, or marine animals, and the eggs, sperm, spawn, larvae, spat and juvenile stages of fish, shellfish, crustaceans and marine animals (Fisheries Act, sec. 2)

Fishery: includes the area, locality, place or station in or on which a pound, seine, net, weir or other fishing appliance is used, set, placed or located, and the area, tract or stretch of water in or from which fish may be taken by the said pound, seine, net, weir or other fishing appliance, and also the pound, seine, net, weir, or other fishing appliance used in connection therewith. (Fisheries Act, sec. 2)

Fish habitat: means spawning grounds and nursery, rearing, food supply and migration areas on which fish depend directly or indirectly in order to carry out their life processes (Fisheries Act, sec. 34(1)).

Fish habitat is comprised of those physical, chemical and biological attributes of the environment which are required by fish to carry out their life processes (e.g., spawning, nursery, rearing, feeding, overwintering, migration). Fish habitat refers to freshwater, estuarine and marine environments that directly or indirectly support fish stocks or fish populations that sustain, or have the potential to sustain, subsistence, commercial or recreational fishing activities.

Fishing: means fishing for, catching or attempting to catch fish by any method (Fisheries Act, sec. 2).
Harmful alteration, disruption or destruction of fish habitat (HADD): any change in fish habitat that reduces its capacity to support one or more life processes of fish.

Harmful alteration of fish habitat: any change to fish habitat that indefinitely reduces its capacity to support one or more life processes of fish but does not completely eliminate the habitat.

Mitigation: actions taken during the planning, design, construction and operation of works and undertakings to alleviate potential adverse effects on the productive capacity of fish habitats.

Net gain: an increase in the productive capacity of habitats for selected fisheries brought about by determined government and public efforts to conserve, restore and develop habitats.

No net loss: A working principle by which the department strives to balance unavoidable habitat losses with habitat replacement on a project-by-project basis so that further reductions to Canada's fisheries resources due to habitat loss or damage may be prevented.

Obstruction: any slide, dam or other obstruction impeding the free passage of fish (Fisheries Act, sec. 2).

Productive capacity: The maximum natural capability of habitats to produce healthy fish, safe for human consumption, or to support or produce aquatic organisms upon which fish depend.

Productive capacity is analogous to carrying capacity, which can be defined as the maximum biomass of organisms that can be sustained on a long-term basis by a given habitat.

Protection (of habitats): prescribing guidelines and conditions, and enforcing laws for the purpose of preventing the harmful alteration, destruction or disruption of fish habitat.

Redesign of a project: any change to a project so that it no longer has negatives impacts on fish habitat.

Redesign measures might include building an open concept pier rather than an infilled structure, modifying the orientation or length of a breakwater, or using a different material in the construction of a wharf.

Relocation of a project: physical moving of a project, or part of a project, to eliminate adverse impacts on fish habitat. Examples of projects where relocation might be required include moving a bridge downstream to protect a spawning ground or moving a dredged material ocean dump site to protect a lobster ground.