Key Concepts

The definitions and descriptions of key concepts mentioned on this page are provided for working purposes only. They do not imply that these have been endorsed or recommended by FAO, or any RFB or RFMO, in preference to others of a similar nature that are not mentioned, and do not provide an official interpretation of the instruments from which they have been drawn. 




Deep-sea fisheries

Various depth limits have been used to define what constitutes deep-sea fisheries. The Deep-sea Fisheries Guidelines do not define deep-sea fisheries, but characterize deep-sea fisheries as fisheries in which the total catch includes species that can only sustain low exploitation rates and where the gear is likely to contact the sea floor during the normal course of fishing.

FAO in a global review has included for review deep-sea fisheries that target demersal and benthic species and are likely to contact the sea floor during the course of the fishing operation. Fishing depth was not considered a major criterion, but the review generally included fisheries conducted below 200 metres on the continental shelf or isolated typographical features such as seamounts, ridge systems and banks.

FAO. 2009. International Guidelines for the Management of Deep-sea Fisheries in the High Seas. Rome. 73pp.

Bensch, A., Gianni, M., Gréboval, D., Sanders, J.S. & Hjort, A. 2009. Worldwide review of bottom fisheries in the high seas. FAO Fisheries and Aquaculture Technical Paper No. 522, Rev. 1. Rome, FAO. 145pp.

Areas beyond national jurisdiction

Areas beyond national jurisdiction (ABNJ) consist of the high seas (see below) and the “Area” (see below).

High seas

All parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a State, or in the archipelagic waters of an archipelagic State.

United Nations Convention on the Law of the Sea (UNCLOS). 1982. Article 86.

The Area

The Area refers to the sea bed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction. This area is confined by the outer limit of the continental shelf of coastal States, which is delimited pursuant to article 76 UNCLOS. Coastal States exercise sovereign rights for the purpose of exploring and exploiting the natural resources of the continental shelf.

United Nations Convention on the Law of the Sea (UNCLOS). 1982. Article 1(1).

Fisheries management

The integrated process of information gathering, analysis, planning, consultation, decision-making, allocation of resources and formulation and implementation, with enforcement as necessary, of regulations or rules which govern fisheries activities in order to ensure the continued productivity of the resources and accomplishment of other fisheries objectives. 

FAO. 1997. Fisheries Management. Technical Guidelines for Responsible Fisheries. No. 4. Rome. 82pp.   

Ecosystem approach to fisheries

An approach to fisheries management and development that strives to balance diverse societal objectives, by taking into account the knowledge and uncertainties about biotic, abiotic and human components of ecosystems and their interactions and applying an integrated approach to fisheries within ecologically meaningful boundaries. The purpose of the ecosystem approach to fisheries (EAF) is to plan, develop and manage fisheries in a manner that addresses the multiple needs and desires of societies, without jeopardizing the options for future generations to benefit from the full range of goods and services provided by marine ecosystems.

FAO. 2003. The Ecosystem Approach to Fisheries. FAO Technical Guidelines for Responsible Fisheries, No. 4 (Suppl. 2). Rome. 112pp.

Regional fisheries management organizations and arrangements (RFMO/As)

There is no formal definition of RFMO/As. The United Nations Fish Stocks Agreement and certain subsequent agreements refer to regional fisheries management organizations and arrangements. A working definition is provided:

A RFMO is an intergovernmental organization, established by international agreement, with the competence to adopt conservation and management measures. A RFMA is any form of arrangement through which States adopt conservation and management measures that does not provide for the establishment of an organization.

The United Nations Fish Stocks Agreement (1995).

FAO. Regional Fisheries Bodies. [webpage].

Vulnerable marine ecosystem (VME)

A VME is described in the Deep-sea Fisheries Guidelines by its characteristics and by its vulnerability. Vulnerability is dependent upon the nature of the fishery and hence region dependent.

FAO. 2009. International Guidelines for the Management of Deep-sea Fisheries in the High Seas. Rome. 73pp.

Significant adverse impacts (SAIs)

Adverse impacts are, in this context, negative effects on a VME resulting from damage caused during the operation of bottom-contact fishing gear. The scale and significance of the impact determines whether the impact can be considered an SAI. This occurs when the ecosystem function is impaired and the long-term natural productivity degraded on more than a temporary basis. Ecosystem recovery following impacts is case-by-case dependent, but is considered more than temporary if recovery takes more than      5 – 20 years. Impacts should be evaluated individually, in combination and cumulatively. 

FAO. 2009. International Guidelines for the Management of Deep-sea Fisheries in the High Seas. Rome. 73pp.


A term used in the Deep-sea Fisheries Guidelines to describe when fishing vessels encounter a VME in the course of fishing operations. The definitions of what constitutes an encounter vary between regions.

*See also paragraphs 67 – 69 in the Deep-sea Fisheries Guidelines

Regional Definitions

Encounter protocols

A protocol or measure identified in advance by the competent authority relating to how fishing vessels in deep-sea fisheries should respond to an encounter of a VME during the course of fishing operations. Types of encounter protocols also vary between regions.

*See also paragraph 67 in the Deep-sea Fisheries Guidelines

Regional Definitions


A large isolated elevation characteristically of conical form. Seamounts are under-sea mountains whose summits lie beneath the ocean surface. They are usually volcanic in origin and are generally defined as having an elevation of greater than 1 000 metres from the seabed.

Cochrane, K.L. (ed.). 2002. A fishery manager’s guidebook. Management measures and their application. FAO Fisheries Technical Paper No. 424. Rome. 231pp.


A seamount with a truncated, flat top surface.

Pitcher, T.J., Morato, T., Hart, P.J.B., Clark, M.R., Haggan, N. & Santos, R.S. (eds.). 2007. Seamounts: Ecology, Fisheries & Conservation. Fish and Aquatic Resources: Series 12. Blackwell Publishing, Oxford, United Kingdom.

Mid-ocean ridge

A continuous range of undersea volcanic mountains that encircles the globe almost entirely underwater. 

"Mid-ocean Ridges". Woods Hole Oceanographic Institution. 17 July 2015.