Spring migration and larvdrift
Soon after the ice has disappeared from
shallow waters, the shrimp migrates from its winter habitat into deeper
water. Most of the individuals are about one year old and about 5-15 mm
The common shrimp becames sexually mature at about one year.
Some are hermaphrodites, that start as males and later transform into
females. It normally reproduces 3-5 times each season, producing thousands
of eggs each time. After the female has sloughed her skin she lays on
her side to enable copulation. When egg laying takes place, she attaches
the eggs to the base of her swim legs and as far up as her last legs.
After 4-8 weeks the eggs hatch while she is in deeper water, thereafter
the larvae swim up towards the surface. The common shrimp has five larvae
stages, with intermittant sloughing of its skin. From June-July, after
4-5 weeks as a larva, the shrimp drifts into shallow sandy bottomed areas
where it falls to the bottom. The last group of larvae fall to the bottom
Up until October, large quantities of young shrimps grow
up in these shallow sandy bottomed areas. The species is very common,
with up to 6-100 individuals per m2. Shrimps are preyed upon
by fish, for example cod when it visits shallow sand bottoms, because
of this, shrimps are seldom older than four years.
The shrimps life
cycle and seasonal migration.
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