Atlantic herring (Clupea harengus)
Also known as: herring, Sea Atlantic herring, yawling
Morphology & Biology
The Atlantic herring (Clupea harengus) is a coastal pelagic fish and one of the most abundant fish species in the world. They can grow up to 45cm long and reach 1.1kg in weight. This species is slender with a rounded belly, and their colouring is mostly silver with a blue or green back. Adults generally mature by four years of age and can live more than 15 years. Mainly planktonic feeders, Atlantic herring feed on zooplankton, krill and fish larvae. They support a range of predators, being heavily preyed upon by sharks, seabirds, marine mammals and skates. They are therefore a vital part of the oceanic food chain as a crucial prey species for a wide variety of marine life.
Individuals reach sexual maturity between the age of three to nine years. At any month of the year, one of the many populations around the globe will be spawning. Herring in the North Sea spawn between January and April, when the water temperature is no more than 7 degrees celsius. The eggs are sticky and laid on marine vegetation, rocks or gravel on the seabed, where they remain until the larvae hatch after roughly 10 days.
Distribution
Found on both sides of the Atlantic Ocean, the distribution of Atlantic herring ranges from the northern Bay of Biscay to Iceland and southern Greenland, and eastward to Spitsbergen, including the Baltic. They are also seen along the continental shelf and coastal waters from Labrador to Cape Hatteras, North Carolina.
Atlantic herring are pelagic and live in the open ocean and offshore banks. Adults migrate across hundreds of kilometres of ocean during their life. In the winter, schools of migrating Atlantic herring can join forces, forming massive expanses of fishes as far as the eye can see. In the North Atlantic, people have observed herring schools occupying up to 4.8km3 of water volume.
Threats
Atlantic herring are suffering from being caught by fishers as well as habitat loss. Gravel is an important habitat for herring spawning, because they lay their eggs onto the substrate. Activities such as the extraction of marine substrates, bottom trawling, dredging or underwater construction can destroy large areas of spawning ground and wipe out entire generations of offspring. The Atlantic herring are considered ‘least concern’ by the IUCN.
Fisheries & Aquaculture
During the 1970s, herring populations in parts of the north Atlantic collapsed catastrophically, virtually wiping out the Icelandic herring industry at that time. In particular, herring populations in the North Sea and west of Scotland experienced severe fishing pressure, leading to their collapse and commercial extinction. Although it has been suggested that numbers have since recovered, global catches within the last ten years have shown an increase, so fishing is still considered a significant threat to this keystone species. The major northern populations in the Northeast Atlantic, such as the Atlanto-Scandian herring and Icelandic summer spawning herring, are incredibly unstable, recovering slowly in comparison to other stocks. Even worse, one large Japanese Atlantic herring population experienced a major collapse 50 years ago after intense overfishing of nearly a million tonnes annually, from which it has never recovered.
Since Atlantic herring school in large numbers, the preferred method of capture is using purse seiners But within the EU, pelagic trawlers are also used in the commercial capture of this species.
Fun fact
Atlantic herring are known to communicate with each other by the ejection of air from the anal duct – yes exactly, they’re communicating by ‘farting’.
