Morphology & Biology
Atlantic herring is a coastal pelagic fish and one of the most abundant fish species in the world. They can grow up to 45 cm long and reach 1.1 kg in weight. This species is slender with a rounded belly, and their colouring is mostly silver with a blue or green back. Adults are mature at 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. Thus, they are a very important part of the oceanic food chain and crucial prey species for a wider 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 celcius. The eggs are sticky and laid on marine vegetation, rocks or gravel on the seabed, where they remain until the larvea hatch after roughly 10 days.
Found on both sides of the Atlantic Ocean, the distribution of Atlantic herring is from northern Bay of Biscay to Iceland and southern Greenland, eastward to Spitsbergen, including the Baltic. They are also seen along the continental shelf and coastal waters from Labrador to Cape Hatteras, North Carolina.
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 fish as far as the eye can see. In the North Atlantic, people have observed herring schools occupying up to 4.8 km^3 of water volume.
Atlantic herring is suffering from overfishing and 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 constructions can destroy large areas of spawning ground and whipe out a whole generation of offspring.
Fisheries & Aquaculture
During the 1970s, the herring population in parts of the north Atlantic collapsed catastrophically, virtually wiping out the Icelandic herring industry at that time. In particular, the North Sea and west of Scotland herring stocks experienced severe overfishing in the past, leading to collapse and commercial extinction. Although it has been suggested that stocks have since recovered, global catches within the last ten years have shown an increase, so overfishing is still considered a large threat to this keystone species. The major northern stocks in the Northeast Atlantic, such as the Atlanto-Scandian herring and Icelandic summer spawning herring, are incredibly unstable, seemingly recovering slowly in comparison to other stocks. Even worse, one large Japanese population experienced a major collapse 50 years ago after intense overfishing of nearly a million tonnes annually, from which it has never recovered.
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… :)