Really Striking Facts About Herring Fish, Animal Sake

Herrings are widely found in the shallow waters of the North Atlantic and North Pacific oceans. They have a small head and a bright silver body. Here, you can discover some interesting facts about herrings, their hunting style, reproduction, and the peculiar habit of forming schools.

Scientific Classification

The herring belongs to the family Clupeidae, which contains about 200 species. The name "herring" is used for several species of this family. The most important and abundant species belong to the genus Clupea. These are the Atlantic herring (Clupea harengus), the Pacific herring (Clupea pallasii), and the Araucanian herring (Clupea bentincki). Together, these three species account for about 90% of all herrings caught. Among them, the Atlantic herring alone accounts for more than half.

Physical Appearance

Close-up side view of an Atlantic herring showing its silver scales, single dorsal fin, and forked tail — The Atlantic herring has a streamlined silver body, a single dorsal fin, and a deeply forked tail.

Herrings are small, silver-colored fish. One important feature is that they have a single dorsal fin with no lateral line or spines, unlike many other fish. A few species have pointed scales. The tail is bifurcated, shaped like a fork. They have a protruding lower jaw on a small head, and a laterally flattened, slender, sleek body.

Their flashy silver color helps hide them in the surrounding water and protects them from predators. But that same feature also makes it easy for humans to spot and catch them.

Atlantic Herring

The Atlantic herring can grow up to 18 inches in length. Its body is fragile and fusiform, that is, it tapers at both ends. The dorsal fin sits roughly midway along the back. It has a greenish or grayish-blue back and a silvery abdomen. You can tell it apart from other herrings by a distinctive circle of small teeth on the roof of its mouth. This fish can weigh up to 1.5 pounds.

Pacific Herring

The Pacific herring can grow up to 15 inches in length. It has a laterally compressed body with a single dorsal fin placed midway along the body, and a deeply forked caudal (tail) fin. Its abdomen and sides are silvery-white, while the back is bluish-green. Unlike some relatives, this fish does have scales on its head and gills, and it also has large, protruding ventral scales.

Araucanian and Baltic Herring

The Araucanian herring, also called the Chilean herring, is dark blue on its back with a silvery abdomen. The Baltic herring is the smallest of its relatives, it grows to just 14 to 18 cm in length.

Herring Range and Habitat

World map showing the range of Baltic, Atlantic, Pacific, and Araucanian/Chilean herring — Herring species are spread across temperate waters of both the North Atlantic and North Pacific. Araucanian herrings live off the west coast of South America.

Herrings live in temperate waters of the North Pacific and Atlantic oceans. Atlantic herring are found in many places, including the Gulf of Maine, the English Channel, the Bay of Fundy, the Denmark Straits, the Norwegian Sea, the North Sea, the Celtic Sea, the Irish Sea, and the Bay of Biscay.

The Pacific herring lives along the California coast from Baja California northward to Alaska and the Bering Sea. In Asia, it can be found south of Japan. Araucanian herring are found along the west coast of South America.

What Do Herrings Eat?

These fish thrive on tiny organisms such as plankton, crustaceans, and fish larvae. Phytoplankton is the main food source for young herrings. Adults feed on zooplankton (including copepods, pteropods, and small crustaceans) as well as krill, mysids, annelids, Calanus, fish larvae, larval snails, small fish, and even small animals. Herrings keep their mouths open while swimming, and in the process filter the plankton that passes through their gills.

Herring Life Cycle

Mating

Herrings reach sexual maturity when they are 3 to 4 years old. Most herrings live for 12 to 16 years. However, Australian herring can live from 23 to 25 years. Fertilisation is external, both the female and the male release masses of sticky eggs and milts at the same time. Some fish travel to coastal rivers to spawn, while Atlantic herrings usually spawn in coastal waters and in offshore banks.

Spawning

Thousands of tiny herring eggs stuck to gravel and stones on the ocean floor, with a few transparent larvae visible — Herring eggs sink to the bottom and stick to gravel, stones, and seaweed. They cannot survive above 66°F.

Mid-summer and December are the ideal times for spawning. Eggs usually take about two weeks to hatch. A female can lay from 20,000 to 40,000 eggs, depending on her size and age. The eggs sink to the bottom and stick to gravel, stones, seaweed, and other objects. Each egg is about 1 to 1.4 mm in diameter, and they cannot survive at temperatures above 66°F.

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Growth of Larvae

When a herring hatches, the larva is usually just 5 to 6 mm in length. Its body is nearly transparent, though the eyes are pigmented. There is a small yolk sac that gets absorbed as the larva grows. The larva starts to look like a tiny herring when it reaches about 40 mm long. Young fish generally reach adulthood in about 3 to 4 years.

How Herrings Feed

Filter Feeding Technique

During the day, herrings stay in deep water to avoid predators. At night, when the risk of being spotted is lower, they come up to the surface. They keep their mouths open while swimming, filtering the plankton that passes through their gills. When prey is highly concentrated, all the members of the school swim with their mouths open and their opercula (gill covers) fully expanded.

Synchronized Feeding

Juvenile herrings have a clever way of catching copepods, tiny shrimp-like creatures. They swim in a grid pattern, keeping a fixed distance between each fish equal to the length of a copepod's escape jump. Copepods use their antennae to sense pressure waves from approaching predators. When a copepod detects danger, it jumps a set distance and then waits about 60 milliseconds before jumping again. By swimming in formation, the endless stream of herrings ensures that eventually one of them will be right where the copepod lands.

Predators of Herrings

Herrings have many natural enemies. Apart from humans, marine mammals such as dolphins, porpoises, orcas, whales, seals, and sea lions all prey on them. Fish like sharks, salmon, tuna, cod, halibut, swordfish, and striped bass are major predators too. Seabirds are another important class of predators.

A group of herring swimming together in the ocean with light filtering from above — By swimming in massive schools, herrings make it harder for a single predator to pick off one fish from the crowd.

Frequently Asked Questions

What family do herrings belong to?

The family Clupeidae, which contains about 200 species.

How do herrings feed?

They swim with their mouths open at night, filtering plankton through their gills.

How large can a herring school get?

A school in the North Atlantic can be up to 4.8 cubic kilometers with billions of fish.

How long have humans eaten herrings?

Since 3000 B.C., making them one of the oldest harvested fish in history.

Herrings and Humans

Herrings have been consumed by humans since 3000 B.C. They have enormous commercial importance and are used as a delicacy in many pasta and salad dishes. They can be fermented, pickled, smoked, cured, and eaten raw. They are also used to make fish oil. Herrings are an excellent source of vitamin D, omega-3 fatty acids, and DHA (docosahexaenoic acid).

Herring prepared as food on a plate, showing the baked fish dish — Herrings can be baked, smoked, pickled, or eaten raw, and they are packed with omega-3 fatty acids and vitamin D.

The Schooling Habit of Herrings

Herrings are famous for swimming in huge groups called schools. They generally move together in the same direction toward shore in order to spawn. While swimming in vast schools, they provide food for large predators.

Scientists estimated that a herring school in the North Atlantic can be up to 4.8 cubic kilometers in size, with a density of 0.5 to 1 fish per cubic meter, which means there can be billions of fish in a single school.

Pros and Cons of Schooling

The most interesting thing about a school is its precise spatial arrangement. Every fish keeps a constant distance from its neighbors, which helps maintain a steady cruising speed. Scientists are not completely sure why herrings form such schools, but possible advantages include predator confusion, better synchronized hunting, and improved orientation. There are downsides too. Schooling can lead to the depletion of food and oxygen in a small area, and a build-up of waste products in the water nearby.

Term	What it means
Clupeidae	The fish family herrings belong to, includes about 200 species of small, schooling, silvery fish.
Fusiform	Spindle-shaped, tapering at both the head and the tail. This shape makes herrings fast and streamlined.
Zooplankton	Tiny animals that drift in the ocean, including copepods and krill. Adult herrings depend on them as a main food source.
Copepod	A tiny shrimp-like creature found in the ocean. Young herrings hunt copepods by swimming in a grid formation.
Opercula	The gill covers on a fish. When herrings filter-feed, they swim with their opercula fully expanded to let water pass through.
Spawning	When fish release their eggs and sperm into the water. Herrings spawn in mid-summer and December in coastal waters.

Really Striking Facts About Herring Fish

Scientific Classification