Members of the Clupeidae family form one of the most important of the world’s fisheries resources. Landings of Clupea harengus increased after the Second World War, though subsequent over-fishing and a reduction in the number of young produced caused a collapse in numbers during the early 1970’s.

In brief

• Common in waters surrounding Northern Ireland.
• Valuable food fish.
• Main threat from overfishing.

Species description: Herring is a flat sided fish with large fragile scales which can easily be removed when handled. The top is a deep blue colour which becomes lighter on the sides to silvery-white on the belly. It can grow to 45 cm and attain a weight of 1 kg. The belly is rounded although in young fish it is keel like. The dorsal fin is above or in front of the pelvic fin but behind the deepest part of the body. The lower jaw sticks out in front of the upper jaw when closed. At all stages of its life herring are preyed upon by numerous predators including seabirds, dolphins and other fish. The food herring eats varies with time and place, generally however the young feed on plankton and adults feed on crustaceans and fish larvae. Invertebrates such as arrow-worms are also very important in its diet. Herring forms distinct breeding stocks (or races) which are recognisable from their spawning grounds.

Life cycle: Herring are a migratory species moving between feeding grounds and spawning areas. Locally herring spawn off the Co. Down coast during the autumn and early winter, when they are also targeted by a small drift net fishery. Throughout UK waters different stocks of herring are known to spawn at various locations in any one month of the year. This enabled fleets of herring boats, following the herring spawning events to fish throughout the year. Herring spawn on banks of gravel and shell. The eggs are heavier than seawater and are shed close to the bottom forming a mat often several eggs deep. The larvae are approximately 6mm on hatching, the young form large schools and are particularly common inshore throughout their first year. Individuals mature at ages ranging from three to nine years depending on their breeding stock.

Similar species: Small juvenile herring can look very similar in shape and colour to sprat Sprattus sprattus, the difference being that sprat has a rough edge along the belly where herring does not.

How to see this species: Herring shoals were traditionally searched for from the tops of sea cliffs, it is easier however to see herring being landed at local ports during the local fishing season (September to November). Populations are in decline.

Current status: Declining. Many herring stocks including the Irish Sea stock were considered by management organisations to be fished within 'sustainable limits' however the population is now known to be in decline. Irish Sea, Celtic Sea and SW Ireland stock decreasing since 2011 and fishing mortality increasing; Subdivision 6a (West Ireland and Scotland) also exhibiting decline (ICES 2019) with decline in spawning stock biomass and recruitment since 2000.

Irish Sea herring are typically exploited as shoals around the Isle of Man and adjacent areas during the autumn. Herring have an important role in the marine ecosystem. They are one of the dominant fish which feed on plankton, transforming the plankton at the bottom of the food chain to higher trophic or feeding levels, e.g. for cod, seabirds and marine mammals. They are also considered to have a major impact on other fish stocks as prey and predator, and are themselves prey for seabirds and marine mammals.

Why is this species a priority in Northern Ireland?

• Criterion 2: Decline based on available data and expert judgement.

Threats: In the mid-20th century herring was considered to be one of the most commercially valuable food fish species. Stocks showed a strong reduction in the 1970’s from global landings. The biggest threat to this species is from over fishing. In addition spawning and nursery areas of herring are sensitive and vulnerable to marine aggregate extraction.

Action: Records of new sites for this species, with details of habitat and population are always valuable. Observations with a photograph can be recorded using iNaturalist, find the MBDP-NI iNaturalist project here.

Alternatively these can be sent to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT18 0EU. Tel 028 9039 5257 or e-mail cedar.records@nationalmuseumsni.org, or via the online portal.

Objectives:

• Avoid eating herring from stocks which are depleted and where fishing is at unsustainable levels, or preferably avoid the consumption of commercially caught seafood, as previous 'sustainable' fishing has caused populations to crash.
• Explore sustainable exploitation of herring through a stakeholder endorsed management plan.
• Work with relevant industries (aggregate extraction, renewable energies) to identify and protect spawning areas.

Conservation:

• Fishery managed through closed areas protecting spawning fish, and annual TACs (Total allowable catch)
• Included in the Grouped Species Action Plan for commercial marine fish
• NERC Act 2006 Species of Principal Importance in England (Section 41) and Wales (section 42)
• Scottish Biodiversity List of species of principal importance for biodiversity conservation in Scotland
• UK list of Priority Habitats and Species 2007

Distribution Map from NBN: Clupea harengus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Clupea harengus at iNaturalist World Species Observations database.

WoRMS: Clupea harengus at World Register of Marine Species. Accepted name: Clupea harengus Linnaeus, 1758. AphiaID: 126417.

Classification: Biota; Animalia; Chordata; Vertebrata; Gnathostomata; Osteichthyes; Actinopterygii; Actinopteri; Teleostei; Clupeiformes; Clupeoidei; Clupeidae; Clupea