About Clupea harengus Linnaeus, 1758
Scientific name: Clupea harengus Linnaeus, 1758, common name Atlantic herring. Atlantic herring have a fusiform body. Gill rakers in their mouths filter incoming water, trapping zooplankton and phytoplankton. Atlantic herring are generally fragile. They have large and delicate gill surfaces, and contact with foreign matter can strip away their large scales. They have retreated from many estuaries worldwide due to excess water pollution, although herring have returned to some estuaries that have been cleaned up. The presence of their larvae indicates cleaner and more oxygenated waters. Atlantic herring can be found on both sides of the Atlantic Ocean. They shoal and school across North Atlantic waters including the Gulf of Maine, the Gulf of St Lawrence, the Bay of Fundy, the Labrador Sea, the Davis Straits, the Beaufort Sea, the Denmark Strait, the Norwegian Sea, the North Sea, the Skagerrak, the English Channel, the Celtic Sea, the Irish Sea, the Bay of Biscay and Sea of the Hebrides. Although Atlantic herring are found in the northern waters surrounding the Arctic, they are not considered to be an Arctic species. Herrings reach sexual maturity when they are 3 to 5 years old. The life expectancy once mature is 12 to 16 years. Atlantic herring may have different spawning components within a single stock which spawn during different seasons. They spawn in estuaries, coastal waters or in offshore banks. Fertilization is external, as in most other fish: the female releases between 20,000 and 40,000 eggs and the males simultaneously release masses of milt so that they mix freely in the sea. Once fertilized, the 1 to 1.4 mm diameter eggs sink to the sea bed where their sticky surface adheres to gravel or weed. They mature in 1–3 weeks; in 14–19 °C water it takes 6–8 days, in 7.5 °C it takes 17 days. They will mature only if the water temperature stays below 19 °C. The hatched larvae are 3 to 4 mm long and transparent except for the eyes which have some pigmentation. Herring-like fish are the most important fish group on the planet. They are also the most populous fish. They are the dominant converter of zooplankton into fish, consuming copepods, arrow worms chaetognatha, pelagic amphipods hyperiidae, mysids and krill in the pelagic zone. Conversely, they are a central prey item or forage fish for higher trophic levels. The reasons for this success are still enigmatic; one speculation attributes their dominance to the huge, extremely fast cruising schools they inhabit. Orca, cod, dolphins, porpoises, sharks, rockfish, seabirds, whales, squid, sea lions, seals, tuna, salmon, and fishermen are among the predators of these fishes. Herring's pelagic prey includes copepods (e.g. Centropagidae, Calanus spp., Acartia spp., Temora spp.), amphipods like Hyperia spp., larval snails, diatoms eaten by larvae below 20 millimetres, peridinians, molluscan larvae, fish eggs, krill like Meganyctiphanes norvegica, mysids, small fishes, menhaden larvae, pteropods, annelids, tintinnids eaten by larvae below 45 millimetres, Haplosphaera, Pseudocalanus.
