herring's habitat is in the North Atlantic, from the Barent Sea to the
Byscaya Bay, and from Greenland, Labrador south to Cape Hatteras in
North Carolina in the USA. Herring is found all around Iceland.
It is an up to mid sea species, which spawns on the ocean floor.
It can be found between 20 and 250 metres depths. It does not
seem to be much affected by the salinity of the sea, and is sometimes
found wandering into river estuaries.
It feeds mainly off crustaceans and krill. Many fish species feed
off its roes, especially the haddock. Both the mature herring
and its fries are eaten by many fast swimming species, i.e.
Pleurotremata and cod. Birds, seals and whales, especially
killer whales, prey on it as well.
Three stocks of herring have been discovered around Iceland, two
Icelandic (spring and summer spawning stocks) and the Norwegian spring
spawning stock, which migrates into the Icelandic fishing zones for
feeding during summer. The Icelandic summer spawning stock
breeds in the bays and fjords off the northwest, north, and northeast
coasts until it is two years old. During the third year it
migrates to the ocean south of the country, where it spawns as well as
off the west coast.
The Norwegian stock, which migrated earlier to Icelandic waters,
spawns off the west coast of Norway. Mature herring came here to
feed, when spring started in the ocean. In June or in the
beginning of July, it had arrived at the fishing grounds off the north
coast. Late in the sixties the stock collapsed, most likely
because of the overexploitation of the young herring.
During the second autumn of the herring's life, it reaches 7-10
centimetres length and 10 grammes in weight. The next summer its
length is double and its weight reaches 50-70 grammes in its third
year. The summer spawning stock reaches puberty at the age of
four and its estimated maximum age is 20-25 years.