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Deep-sea fish

Orange roughy, Hoplostethus atlanticus

Deep-sea fishes: it may be that their life histories make them especially vulnerable to exploitation.


Deep-sea fish come in many shapes and sizes, and have fascinating life histories and ecological adaptations. However, it is a sad reality that many deep-sea fisheries resources soon become overexploited, even depleted, before science-based management measures are introduced.

A major obstacle is that the scientific information required for assessing vulnerability and giving precise advice on management measures remains limited. This is a concern for international advisory bodies such as ICES (the International Council for the Exploration of the Sea ) and OSPAR (the Oslo-Paris Commission), as well as national and international management authorities, the fishing industry, and non-governmental conservation groups.

Known features

Alfonsino, Beryx splendens

Deep-sea fishes are widely distributed across the Atlantic, and many live for several decades. The classical highly priced deep-sea species, orange roughy, may become a hundred years old, perhaps even more than 150yrs.

Most species mature at high ages and have low fecundities, hence their reproductive capacity is limited. Growth rates tend to be slow, and natural mortalities low. Such life history features are incompatible with high exploitation rates.


Although some characteristics of deep-sea fish and their habitats have been studied previously, the database available for assessing vulnerability to modern exploitation remains very incomplete.

Much information is qualitative, based on limited observations or the use of unvalidated techniques. A lot of the work has not been properly evaluated and reviewed, and a major part of current data can only be found in the rather inaccessible "grey literature" (unpublished reports etc.).

The solution

Black scabbardfish, Aphanopus carbo

The provision of new data is hampered by lack of international dedicated efforts and opportunities. Therefore, mobilisation and networking of biologists and ecologists with special competence in deep-sea fish studies is essential.

MAR-ECO offers this opportunity, and in a special project lead by Dr Maurice Clarke of the Marine Institute in Ireland, a dedicated team of scientists will pursue the study of life history strategies of deep-sea fish.

Currently this team includes very competent partners from Norway, Iceland, France, Spain, Portugal, USA, and Russia and more may be recruited as the project develops. They will focus on reproductive biology and ecology, growth studies, and mortality estimation for a limited number of key target species of the fisheries, utilizing sampling opportunities on MAR-ECO cruises. Samples will not only be collected on the Mid-Atlantic Ridge, but also on adjacent island and continental slopes. The project will also focus stongly on development and evaluation of methodology such as e.g. age determination procedures.

Such a life history strategy project within MAR-ECO will make a significant contribution to the efforts required for a responsible assessment and management of deep-sea fisheries resources. In addition it will add valuable end exciting new information to science on species that are exotic and poorly known. Disseminated in a popular manner such scientific knowledge is of considerable interest well beyond the scientific audience. Studying the life histories of deep-sea fish will advance basic biological and ecological science and will also contribute to the sustainable management of internationally controversial fisheries.

Read about some Russian exploratory fishery data

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