Northern Ireland's Priority Species

Merluccius merluccius – european hake

 

Merluccius merluccius (Linnaeus, 1758)
Family:

Hake is the only member of the family Merlucciidae in European waters. It is a cod like fish and was once included in the cod family but has been designated itís own family status. The characteristics for this predatory fish are its black mouth and gills as well as its pointed head. It is a valuable resource for many fisheries and is landed as targeted or by-catch.

In brief

  • Hake is a migratory species and can be found throughout the Irish sea
  • Prefers muddy and rocky habitats
  • Lives at depths between 150-550m. Seen all year round in fishermenís trawls, at fish markets and in the supermarket
  • Has high quality flesh and is valued commercially
  • It is a UK Priority Species
  • Main cause of decline is overfishing and high numbers of discards of juveniles
  • Slow growth and late maturity makes hake prone to overfishing

Species description
Hake has a slender body a large head and snout, and powerful large curved teeth. It has well developed jaws and no chin barbell. The first dorsal fin is triangular in shape, the second dorsal and anal fin are long with a shallow dip two-thirds along their length. The lateral line is straight, and it is greyish blue on top and silvery white on the sides and belly. The inside of hake mouth and gills are black. During the day hake remain near the bottom but at night they come to the surface in search of food. They feed mainly on fish and squids but the young eat crustaceans. Hake can reach a maximum size of 140cm and weight of 15kg, but average size is closer to 45cm.

Life cycle
Hake spawn in several batches from February to July in deep water typically more than 200m. After the larval stage juveniles use the currents to carry them into shallow water with a muddy seabed. There are two major nursery areas, the Bay of Biscay and off southern Ireland. As hake become sexually mature (at around 3 years and 39cm for males, and around 4 years and 47cm for females) they disperse to offshore regions of the Bay of Biscay and Celtic Sea

Similar species
There are no similar species to hake its shape and colouring is quite distinctive.

How to see this species
As hake typically lives in deep water it is unlikely to be seen except by fishermen though it can be kept in aquariums. It is more likely to be seen at fish markets or in the supermarket.

Current status
Although there is no clear evidence of multiple populations in the Northeast Atlantic scientists assume two stock units of hake, the Northern and the Southern. Hake in Northern Ireland are incorporated into the Northern stock. Being a migratory species hake is widely distributed and can be found throughout the Irish Sea. ICES states the number of mature fish able to reproduce is increasing in the Northern stock. However although the fishing mortality, which is the number of fish being removed by fishing, is decreasing it is still above a target defined by fishery scientists as the level at which the species can be fished sustainably.

Why is this species a priority in Northern Ireland?

  • Listed as a UK Priority Species
  • UK Biodiversity Action Plan species

Threats/Causes of decline
The main treat is overfishing as hake is caught in mixed fisheries, discards of juvenile hake can be substantial in some areas and fleets. Since hake is a late maturing fish the high numbers of discards of juvenile fish will ultimately pose a threat to the population.

Conservation of this species

Current action

  • In 2009 the European commission adopted a long-term plan to improve the state of the northern hake stock in EU waters
  • A recovery plan was agreed by the EU in 2004 with the aim of increasing the number of fish able to reproduce and reducing the number of fish being discarded
  • Mesh sizes have been increased in areas where juvenile hake were thought to be distributed
  • Designated under the following: NERC Act (2006) Species of Principal Importance for the purpose of conserving biodiversity in England (section 41) and Wales (section 42)
  • Scottish Biodiversity List 2005 of species of principal importance for biodiversity conservation
  • 2007 UK list of Priority Habitats and Species
  • Included in the UK Biodiversity Action Plan under the Grouped Plan for commercial marine fish

Proposed objectives/actions

  • Selecting different mesh sizes of fishing nets to conserve juvenile fish
  • Maintain the number of viable populations of the species
  • Maintain the range of the species
  • Establish appropriate management on appropriate historic sites

What you can do
Choose seafood from sustainable sources in order to promote sustainable resources of hake.

Further information

Links
European Commission

JNCC

Grouped Plan for Deep Water Fish

ICES status

Literature
Maitland, P.S. and Herdson, D. (2010). Key to the Marine and Freshwater Fishes of Britain and Ireland. Bristol; Environment Agency 191

Text written by:
Robert Rossell