Herring
The Atlantic herring, Clupea harengus Linnaeus 1758, reaches a maximum length of 45.0 cm and can live up to 22 years. This species dominates global catches, comprising over half of all herrings harvested in fisheries worldwide. The Pacific herring, Clupea pallasii Valenciennes 1847, grows slightly larger at 46.0 cm but has a shorter lifespan of about 19 years. These two species form the genus Clupea, which represents approximately 90% of all commercial herring captures. Other fish share the common name herring without belonging to this specific genus. The Baltic herring, Clupea harengus membras, remains small, measuring only 14 to 18 cm in length. Some species like the toothed river herring, Clupeoides papuensis Ramsay & Ogilby 1886, inhabit freshwater environments rather than saltwater oceans. The International Union for Conservation Nature lists several species as vulnerable or data deficient due to population uncertainties. Scientists distinguish true herrings from lookalikes by examining their single soft dorsal fin and lack of lateral line. A protruding lower jaw further separates them from other silvery fish families.
At least one stock of Atlantic herring spawns during every month of the year across different regions. Greenland populations deposit eggs in water depths of 20 meters while North Sea bank herrings spawn down to 50 meters in autumn. Females may release between 20,000 and 40,000 eggs depending on age and size, averaging around 30,000 per spawning event. These eggs sink to the sea bed where they stick to gravel, seaweed, or stones via a mucous coating. If egg layers become too thick, oxygen depletion causes many to die entangled within mucus webs. Survival rates improve significantly when eggs settle behind solid structures that protect them from predators. Incubation takes approximately 40 days at 4 degrees Celsius but shortens to just 11 days at 12 degrees Celsius. Larvae hatch measuring about 6 mm long with a small yolk sac absorbed before reaching 1 cm. Only the eyes remain pigmented while the rest of the body stays nearly transparent under natural lighting conditions. The dorsal fin forms at 1 cm and the anal fin appears at roughly 1.5 cm. By 30 to 40 mm, the tail becomes well forked and the larva begins resembling an adult herring.
Herrings consume copepods, arrow worms, pelagic amphipods, mysids, and krill within the pelagic zone of oceans. Atlantic cod stands as the top predator in the Baltic Sea, preying directly on both herring and sprat populations. Seabirds, dolphins, porpoises, whales, seals, sea lions, sharks, billfish, tuna, salmon, striped bass, and halibut all hunt herrings as prey. Predators often cooperate in groups using techniques to panic or herd schools into tight bait balls for easier capture. Sailfish raise their sails to appear larger while swordfish charge through bait balls slashing with swords to stun or kill fish. Thresher sharks use long tails to stun shoaling fish by swimming around them and splashing water in pairs or small groups. Spinner sharks charge vertically through schools spinning on axes with mouths open snapping all around. Blue whales perform lunge feeding accelerating from below bait balls to high velocity before opening mouths wide. This extreme method generates water pressure required to expand mouths and engulf huge amounts of water and fish simultaneously. Copepods form the largest animal biomass on the planet yet remain alert enough to sense pressure waves from approaching fish.
During the Middle Ages herring prompted the founding of Great Yarmouth and Copenhagen while playing a critical role in medieval Amsterdam development. In 1274 Thomas Aquinas asked for fresh herring while on his deathbed at the monastery of Fossanova south of Rome Italy. The herring industry became an important part of Scotland North Sea coastal communities economies reaching its peak in the late 19th century. A herring boom saw Shetland and its town Lerwick become known as the herring capital of Europe. Trade in herring has been so significant to many countries that it is regarded as the most commercially important fishery in history. Fishermen caught and ate herring starting at least 3000 BC making it a staple food source throughout human history. Regional recipes include eating raw fermented pickled or cured by other techniques such as being smoked as kippers. An 18th-century newspaper reported three men meeting at the Crown Inn Everley to eat 60 red herrings with three half-gallon loaves and drink six gallons of beer.
Adult herring are harvested for their flesh and eggs while also serving as baitfish for larger commercial operations. Purse seining methods dominate modern harvesting practices in regions like southeast Alaska where large nets encircle schools near fishing banks. Global trade remains an important sector of many economies around the world today. Scientific study of population dynamics began early in the 20th century when research on herrings proved fundamental to developing fisheries science. Baltic herrings larger than 45 cm may be eaten twice a month according to Finnish Food Safety Authority guidelines due to contaminant levels. Mercury content influences how much fish women planning pregnancy within one or two years can safely consume. Water pollution affects safety limits with PCB and dioxin levels slightly exceeding recommendations for large Baltic specimens. Some sources argue cancer-reducing effects from omega-3 fatty acids statistically outweigh carcinogenic impacts from environmental contaminants. Scientists analyze stomach contents to understand feeding preferences and vertical migration patterns between species competing for limited zooplankton resources.
Herring contains very high levels of long-chain omega-3 fatty acids EPA and DHA which support cardiovascular health. These oily fish provide vitamin D alongside essential nutrients found in oceanic surface waters. Contaminant levels depend heavily on age since size correlates directly with accumulated pollutants over time. Baltic herrings smaller than 17 cm can be eaten freely while larger specimens require consumption restrictions. The Finnish Food Safety Authority advises eating large Baltic herring only twice monthly due to PCB and dioxin presence. Women pregnant or planning pregnancy within next one or two years must consider mercury content carefully before consuming any fish. Omega-3 benefits remain statistically stronger than potential cancer risks from environmental toxins according to some assessments. Regional traditions include fermented pickled smoked cured raw preparations passed down through generations since ancient times. Modern consumers balance nutritional advantages against safety concerns when deciding how often to include herring in diets.
Common questions
What is the maximum length and lifespan of Atlantic herring Clupea harengus Linnaeus 1758?
Atlantic herring reaches a maximum length of 45.0 cm and can live up to 22 years.
How do scientists distinguish true herrings from other silvery fish families?
Scientists identify true herrings by their single soft dorsal fin, lack of lateral line, and protruding lower jaw that separates them from other families.
When did Thomas Aquinas ask for fresh herring on his deathbed at Fossanova monastery?
Thomas Aquinas asked for fresh herring in 1274 while dying at the monastery of Fossanova south of Rome Italy.
Why are Baltic herrings larger than 45 cm restricted to eating twice monthly according to Finnish Food Safety Authority guidelines?
Baltic herrings larger than 45 cm contain PCB and dioxin levels slightly exceeding recommendations so authorities limit consumption to twice per month.
Which species form the genus Clupea representing approximately 90% of all commercial herring captures?
The Atlantic herring and Pacific herring form the genus Clupea which represents approximately 90% of all commercial herring captures worldwide.