What is a Pacific Herring?
Pacific herring (Clupea pallasi
) is a small fish with iridescent silver-white sides and a blue-green back or dorsal surface. Adults are normally about 15-25 cm in length. Pacific Herring are related to the Atlantic variety, though they are smaller and differ somewhat in their spawning behaviour. A herring “ball” results when a school is chased to the surface by predators; they can sometimes be spotted by the presence of a large flock of seagulls noisily feeding on the surface. Herring are a very important food source for many other animals, including diving birds (e.g. cormorants, murres, rhinoceros auklets), fish such as salmon, and mammals including humpback whales, seals and orcas.
Where do Pacific Herring live?
Herring require marine plants such as eelgrass and kelp on which to spawn. Clean water with sufficient nutrients to support these plants is crucial to the survival of herring. Protected areas such as estuaries provide shelter and food for juvenile herring. Offshore, adult herring feed in areas with cool waters that are rich in nutrients and plankton, tiny plants and animals that drift with the ocean currents. Herring are found along the west coast of North America, from Baja California to Alaska, and along the east coast of Russia, China and Japan.
Pacific herring are found seasonally in the Gorge Waterway, moving into the upper reaches past the Gorge Narrows in early spring. This population is considered genetically distinct from nearby populations in other areas of the Salish Sea, but no spawning has been confirmed in the Gorge since the 1970s.
How do Pacific Herring live and reproduce?
Pacific Herring live in dense schools throughout their lives. Once they reach sexual maturity, they migrate from offshore feeding grounds to shallow intertidal areas to spawn, in late March to early April. Since herring have no physical defenses against their many predators, they rely on sheer numbers and schooling behaviour to survive.
Females deposit 20,000 to 40,000 clear, sticky eggs on eelgrass, kelp or other marine vegetation. Males release milky sperm, or milt, into the water. Because schooling and spawning occur in very high densities, the milt can create massive clouds during spawning time that can be seen from a very long distance. Herring spawn events are usually attended by large flocks of gulls and diving birds. Large numbers of seals, sea lions and other animals also congregate to gorge on the abundant fish and eggs. The annual Gray whale migration in early spring coincides with the herring spawn that moves in a northward wave. These bottom-feeding whales target the masses of eggs that blanket the shallow waters of coastal bays.
Ten to 21 days after the eggs are fertilized, 9mm-long herring larvae emerge. In this area of the coast, Pacific herring remain in the Strait of Georgia for their first year, then move to the west coast of Vancouver Island at two to three years of age. Due to intense predation by other animals, out of every 10,000 eggs laid, only one herring is estimated to survive to return to spawn. Herring live to a maximum of about 15 years.
How have people used Pacific Herring?
First Nations communities have fished herring for food throughout their long history in BC and the Pacific Northwest USA. The roe (eggs) was, and still is, especially prized. Tree boughs or kelp blades are suspended in shallow areas where herring are known to spawn. These are later removed to harvest the roe. Today, First Nations are the primary commercial operators of the lucrative spawn-on-kelp industry. The product is sold as a delicacy to Asian markets.
Herring was fished commercially beginning in 1877, primarily as a food export to Asia. Declining markets after the Second World War led to a decline in the value of herring, and it was later processed mainly for low value oil and fish meal. Overexploitation between the 1930s and 1960s resulted in a near crash of Pacific herring stocks in BC; the herring fishery was consequently closed in the 1960s for four years by the federal government.
Today, herring are fished for their roe and in smaller numbers as bait fish. Adult fish are harvested by commercial fishing boats just before they spawn, using seine nets and gillnets. The spawn-on-kelp industry continues to be an important component of the herring fishery.
Why is Pacific Herring important?
Herring provide an important link between tiny plankton and larger fish, marine mammals and birds. They are essential “forage fish” and provide food for many species. This is apparent in the feeding frenzies that result whenever schools of Pacific herring are present. Eggs laid are consumed by humans and birds such as gulls and ducks. Fish, such as salmon, perch, and hake, feed on the larvae shortly after they hatch. Seals, sea lions, whales and numerous types of birds feed on adult herring.
What threatens Pacific Herring?
Stocks of Pacific Herring in Georgia Strait are currently estimated to be in good condition. Besides the ongoing commercial fishery pressure, loss of spawning habitat and degraded water quality are currently the other major threats to herring.
- Harmful chemicals can enter the marine environment through runoff from roads, lawns, and parking lots
- Eelgrass and kelp beds – essential herring habitat – may be damaged from excess sediment or chemical pollution
- Estuaries that provide important rearing and spawning habitat for herring are often damaged by urban development
How can I help protect Pacific Herring?
For information on protecting Pacific Herring, please visit our How Can I Help?
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