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Dieren en planten

Fish   Fish biology   Fish communities   Reproduction of fish   Nurseries   Fish diseases   Marine fauna   Sea fish   Fauna in tidal areas   Fish   
Spawning grounds and nurseries, Ecomare

Reproduction of fish

The releasing of fish eggs and their fertilization is called spawning. Most fish species have a specific place in the sea where they lay their eggs: the spawning grounds. When the eggs hatch, the larvae spend the first part of their life as zooplankton. They are transported by sea currents to places where they can grow best: the nurseries. The Wadden Sea is one such nursery.

  • Millions of eggs
    Egg of a lesser spotted dogfish, with embryo, Ecomare

    Fish often have many offspring, especially those sorts whose eggs drift around in the water. Cod lays up to a million eggs per year. Many fish eggs and larvae are consumed by all kinds of animals, so that only a small selection actually reaches adulthood. The eggs of species such as herring and lesser sandeel are laid on the sea floor. These eggs are less vulnerable, so that the fish can afford to lay fewer eggs. Herring produces 'only' 30,000 eggs per year. Other types, such as the lesser spotted dogfish and the thornback ray, lay even fewer eggs, around 140.

  • Fixed nesting grounds

    Fish have fixed places for reproduction. Herring release their eggs (roe) on gravel or shell banks, among which the English and Scottish coasts. After fertilizing the eggs with seed (milt) by the males, the adult fish return to the northern and central North Sea. Lesser sandeel lay their eggs in sand.

  • From prey to predator

    The larvae of herring, cod, flatfish and many other species fall under animal plankton. They live in the top water layers in the sea and eat mostly copepods. When they grow larger, they can move independently from the water currents. Species such as herring and sprat start to eat larger plankton animals, cod becomes a fish consumer and flatfish direct their attention to prey on the sea floor. The acorn worm (Hemichordata) is first a predator for herring and later a prey.