Common skate (Dipturus Batis)
Species Action Plan
1 Current status
1.1 The common skate is the largest European batoid fish. Females can reach lengths of 285 cm and males 205 cm. They are found in the north-east Atlantic from Madeira and northern Morocco to Iceland and northern Norway. However, tagging records indicate that the majority of fish spend their entire life within a relatively small coastal area.
1.2 It is a demersal, i.e. bottom dwelling, species, usually found in shallow coastal waters and shelf seas to 200 metres, but occasionally down to 600 metres. They hunt crustaceans and fish both in mid water and on the sea bed. Males mature at a length of 125 cm (over 10 years old). Size and age at maturity for females is unknown. Longevity is estimated at 50 years. Mature females can produce up to 40 large eggs (14‑24 cm long) per year, deposited in spring and summer. The young hatch at a length of up to 21‑22 cm.
1.3 The common skate is widely distributed, but very scarce throughout European waters. It has probably been fished to extinction in the Irish Sea and is extremely rare in the central and southern North Sea, the western Baltic and western Mediterranean.
1.4 The status of the stocks is unknown (too few are caught in research cruises to make analysis possible). However, its life-history makes it extremely vulnerable to fisheries, compared to other faster growing rays. Immature fish (<125 cm and <10 years old) are vulnerable to capture in many fisheries and very few juveniles can survive to maturity. Estimates of current fishing pressure on North Sea rays indicate that populations of such a slow-reproducing fish would decrease by about 35% per year, explaining the disappearance of the species here and in many other areas. Nevertheless, it is a relatively robust fish that occasionally survives the rigours of capture in fishing gear and release. It is a popular target for recreational anglers in areas where it still occurs.
1.5 The provisional IUCN Red List assessment for the species is Endangered.
2 Current factors causing loss or decline
2.1 The common skate is vulnerable to capture by many static and towed fishing gear; it is taken both in target fisheries for rays and as bycatch in other fisheries. Its slow growth and large size at maturity mean that juveniles have little or no chance of surviving to maturity in heavily fished areas. Although no longer targeted where it is very scarce, the common skate continues to be caught as bycatch in fisheries for other species, including more fecund rays. Under these conditions commercial extinction can readily be followed by biological extinction.
2.2 It is doubtful that habitat constraints and food availability are of significance in the decline of this species, compared with fishing pressure.
3 Current action
3.1 In 1997, the EU Council of Ministers agreed a precautionary Total Allowable Catch for all skates and rays (combined) in the North Sea. This does not distinguish between species, and is not based on any analytical stock assessments.
3.2 In response to the increasing rarity of the species, the Irish Specimen Fish Committee has removed the species from listings. This has reduced the incentive for anglers to land and kill large individuals in order to enter the record book. UK recreational anglers are encouraged to return skate live to the sea by their national representative organisations.
3.3 The Glasgow Museum tagging programme targeting a resident population in the Sound of Mull area encourages visiting anglers to return tagged common skates unharmed to the sea.
4 Action plan objectives and targets
4.1 In the short-term (up to five years), stabilise refuge populations by minimising fishing mortality and legally protecting the species in at least five key centres of abundance.
4.2 In the long-term: facilitate the migration of common skate from refuge populations to areas within which they are either scarce or have been fished out by minimising fishing pressure on the species. Inevitably, this will take not less than one or two decades due to the species' slow rates of reproduction and growth.
5 Proposed actions with lead agencies
Fishing for common skate is subject to the EU Common Fisheries Policy (CFP) and there is nothing that the UK can do unilaterally to conserve this, or other commercial fish stocks that are of interest to both the UK and other EU fleets. Even within the 6 nautical mile coastal zone, where the UK fishes exclusively and can exercise greater autonomy, most fishery management measures would be of limited value as common skate is not confined to the inshore area. Effective measures must be aimed mainly at modifying the way fisheries are managed under the CFP. Nevertheless, some unilateral action by the UK is possible. In particular, there is a need for increased knowledge of the skate's biology and exploitation, and for improved fisheries statistics. Most existing data are derived from commercial fisheries statistics collected during the period that the species was fished to near extinction from UK waters. These data now need to be augmented by fisheries-independent research data.
5.1 Policy and legislation
5.1.1 Make all skate and ray landings 'skin on' to facilitate species identification and record all species in landing statistics. (ACTION: DANI, MAFF, NAW, SE, SFCs)
5.1.2 Ensure that the necessary research and monitoring programmes are undertaken to provide the basis for analytical stock assessments. (ACTION: DANI, MAFF, NAW, SE, SFCs)
5.1.3 Obtain European Union approval for the introduction of sea fisheries committee bye-laws and Scottish Executive legislation banning landings or imposing minimum landing sizes for common skate taken in UK coastal waters. (ACTION: DANI, MAFF, NAW, SE, SFCs)
5.1.4 Investigate alterations required in European legislation which would enable commercial fish species to be listed under Appendix II and III of the Bern Convention. (ACTION: JNCC)
5.2 Site safeguard and management
5.2.1 Designate at least five refuge areas (see 5.5.1) within which skate are given legal protection from commercial fishing and deliberate killing or retention by anglers (ACTION: CCW, DANI, EN, MAFF, NAW, SE, SNH).
5.3 Species management and protection
5.3.1 Seek protection of the species within UK coastal waters under appropriate fisheries legislation (see 5.1.4) (ACTION: DANI, MAFF, SE, SFCs).
5.3.2 Investigate opportunities for the management or protection of the species within European waters by listing on the appropriate Annex of the Bern Convention. (ACTION: DETR, JNCC).
5.3.3 Protect the species within at least five designated refuge areas using appropriate legislation (see 5.2) (ACTION: CCW, DANI, EN, MAFF, NAW, SE, SNH).
5.4.1 Develop and publicise a code of conduct for the live release of immature common skate by all fishermen, both commercial and recreational. (ACTION: CCW, DANI, DETR, EN, JNCC, MAFF, NAW, SE, SNH)
5.4.2 Develop and publicise a code of conduct for the careful handling (including tag reporting) and live release of all common skate by sports anglers. (ACTION: CCW, DoE(NI), EN, JNCC, SNH)
5.5 Future research and monitoring
5.5.1 Initiate research programmes to monitor life cycles, growth, reproductive capacity and population dynamics (including immigration and emigration); identify centres of distribution of relict populations as locus for refugia; improve fisheries-independent research and data collection. (ACTION: DANI, DETR, JNCC, MAFF, NERC, NAW, SE, SNH)
5.5.2 Improve data collection from remaining commercial landings to improve knowledge of fisheries statistics and exploitation status. (ACTION: DANI, MAFF, NAW, SE, NERC)
5.5.3 Initiate new long-term tagging programmes for the species and DNA studies to determine the extent of exchange between populations. (ACTION: NERC)
5.5.4 Promote research into the survival of common skate released after capture by commercial fishing gear (e.g. trawls). (ACTION: DANI, JNCC, MAFF, NAW, SE, NERC)
5.6 Communications and publicity
5.6.1 Publicise the vulnerability and threatened status of the common skate to commercial and sports fishermen, to minimise mortality in fisheries (ACTION: CCW, DANI, EN, JNCC, MAFF, NAW, SE, SNH).
5.7 Links with other action plans
5.7.1 Reference should be made to the Commercial Fish, Basking Shark and Marine Turtles Action Plans. These action plans are similar in their recommended conservation aims and objectives. Particular attention is drawn to the issue of bycatch in fisheries.
First five years: £18420.00
Second five years: £18080.00
Home - Sea Angling Info - Tag & Release Info - Galleries - Native Marine Aquaria - Links - Contact
Copyright: Davy Holt 1996 - 2005