• Observing and modelling
• Marine Climate Change Centre (MC3)
• Ecosystems and biodiversity
• Assessing human impacts
• Animal health and food safety
• Fisheries information
  • Fisheries Science Partnership
  • Surveys
  • Discards and fishing gear technology
  • Commercial species
  • Under-utilised species
  • Deep-water species, NE Atlantic
  • Species of conservation importance
  • Non-native species
  • Unusual fish
  • Recreational sea angling
  • Ageing fish
  • Fish stomach records
  • Tagging programmes
  • Ecologically important fish habitats
  • Freshwater fisheries
  • Salmonids
  • Eels
  • Fish-eating birds

Related links

• Map of ICES area
• Kitefin shark (PDF, 36 KB)
• Alfonsino spp. (PDF, 43 KB)
• Greater forkbeard (PDF, 55 KB)
• Red (blackspot) seabream (PDF, 37 KB)
• Greater siver smelt or argentine (PDF, 35 KB)
• Portuguese dogfish (PDF, 54 KB)
• Leafscale gulper shark (PDF, 49 KB)
• Roundnose grenadier
• Blue ling (PDF, 55 KB)
• Deep-water red crab (PDF, 43 KB)
• Orange roughy (PDF, 54 KB)
• Black scabbardfish (PDF, 54 KB)

Deep-water species, NE Atlantic

Fisheries

Deep-water fisheries in the NE Atlantic are numerous and diverse and involve vessels from many countries, and only fisheries in which UK vessels participate are described here. UK Fisheries for deep-water species have reduced in size in recent years due to EU conservation legislation (including TACs and vessel licensing) and, for some species, declining catch-rates. However, deep-water issues continue to have a high political and advisory profile in Cefas, Defra, the European Commission and at the United Nations. Cefas staff have played a major role in this advisory process and are currently participating in a EU Framework 7 project "DEEPFISHMAN" - Management and Monitoring of Deep-sea Fisheries and Stocks (April 2009 - March 2012).

A substantial gillnet fishery in 1990s and early 2000s for deep-water 'siki' sharks (principally Portuguese dogfish (Centroscymnus coelolepis) and the leafscale gulper shark (Centrophorus squamosus))in ICES Sub-areas VI and VII was closed in January 2006 as a result of an EU temporary ban on deep-water gillnetting at depths greater than 200 metres. This was largely because of concerns about ghost fishing by lost and abandoned gillnets. NEAFC introduced a similar ban in the NEAFC Regulatory Area. UK longliners fishing for these species in westerly waters were allowed to continue fishing. However, this fishery was also closed on 1 January 2007 as a result of an EU ban on all directed fishing for deep-water sharks that was introduced in accordance with ICES advice that most stocks of deep-water shark are severely depleted. In January 2007 the gillnet fishery was opened but only down to 600 m and catches now comprise mainly anglerfish with a small by-catch of deep-water sharks. 

A UK gillnet fishery for deep-water red crab (Chaceon affinis), was similarly closed by the above-mentioned EU and NEAFC legislation in 2006 and 2007.

A trawl fishery for blue ling in ICES Sub-areas Vb, VI and VII, involving mainly French, Faroeses, German, Norwegian and UK vessels, has gradually declined since the early 1990s due to stock depletion. Fishing was largely targeted at spawning aggregations and currently only by-catches of blue ling are allowed. These are mainly taken in a mixed species trawl fishery involving mainly French, Spanish, Faroese and, to a lesser extent, UK vessels. Other species taken include roundnose grenadier (Coryphaenoides rupestris), black scabbardfish (Aphanopus carbo) and deep-water sharks (the latter as a by-catch). EU protection areas for spawning aggregations of blue ling in ICES Division VIa were introduced in January 2009.

Deep-water species can also be taken as a by-catch in trawl fisheries for anglerfish (Lophius piscatoris and Lophius budagassa) on the continental slope.

Biology

Most deep-water fish species are long-lived, slow-growing, have a low reproductive capacity and are adapted to live in an ecosystem of low energy turnover in which major environmental changes occur infrequently.

Almost all deep-water fisheries in the ICES area have developed without programs in place to collect biological and fisheries data. Data collation and examination only really began in 1994 with the convening of an ICES Study Group, and an assessment working group (WGDEEP) in 2000. European Commission deep-water licensing regulations introduced in 2003 require Member States to implement market sampling and/or observer programmes for deep-water species.

Although biological studies of deep-water species have increased during the last decade, knowledge of biological processes such as growth, feeding, maturation and fecundity still lags behind that of commercially exploited shelf-based species. Little is known about recruitment processes and variation, stock identity, fish migration and fish behaviour.

Although considerable progress has been made in length and age sampling of commercial deep-water landings, there is still scope for significant improvement for many species. Age data are sparse for deep-water fishes. Age determination is difficult because calcified structures such as otoliths frequently display a large number of rings making age interpretation and validation difficult. Amongst the deep-water species currently assessed in the Northeast Atlantic, the greatest progress has been made with roundnose grenadier, orange roughy (Hoplostethus atlanticus), black scabbardfish and blue ling. Few studies have been carried out on the stock-structure of deep-water fish species in the Northeast Atlantic and these were reviewed by WGDEEP in 2007. For assessment purposes, stock units are mostly based on current knowledge of species distribution and commonality of CPUE trends and ecosystem features between ICES areas. Stock units for tusk were recently revised to take account the results from recent genetic studies. Studies on the genetic identity of other deep-water species are ongoing, and alternative methods such as otolith microchemistry look promising. 

Spawning areas for almost all deep-water fish species have not been well defined because there are few research surveys targeted at deep-water stocks and information from commercial trips is sparse. Maturity information for deep-water sharks collected on UK observer trips on commercial vessels will be worked up in 2011 and 2012. However these data, at best, will only provide point estimates of maturity for a small range of fishing grounds at different times of the year. Information on the spatial and temporal location of spawning grounds of blue ling was collated under an EU Framework 6 project "POORFISH", and this combined with further information made available to ICES WGDEEP was used as a basis for EU protection areas introduced in 2009.

Little is known about the migration of deep-water species because conventional tagging methods cannot be used since almost all fish brought to the sea-surface die due to bathymetric shock.

Bathymetric shock also ensures that nearly all discarded deep-water fish die. There is also a paucity of time-series data on discards and this impacts on the quality of stock assessments making it difficult to evaluate the impacts of fishing on the deep-water ecosystem. Also, many deep-water species are susceptible to damage by trawls because their skin is not covered by mucus. Consequently, a high proportion of fish entering trawls but escaping through the meshes probably die.