European Squid - Biology

Biology

This species can be found at depths from the surface to approximately 500 m, but it is most abundant between 20 and 250 m (deeper during the winter months). The population in the northeastern Atlantic spends the winter in deeper waters off Portugal, then moves towards the coast of France in spring, before migrating farther north into the North Sea during May and June where they spawn in depths ranging from 20 to 80 m. A southward migration takes place in autumn. The population found off Morocco and Western Sahara similarly spends the winter months in deeper offshore waters and moves inshore to spawn in spring and autumn. The main juvenile recruitment is in February and March and between July and September. In the western Mediterranean, European squid move into deeper water in late autumn; the largest individuals commence their inshore migration as early as in January and February, while the smaller individuals wait until summer.

The spawning season extends for most of the year but climaxes in early summer and early autumn. Females lay up to 20,000 small eggs, which are deposited in gelatinous tubes containing tens of eggs each. These tubes are attached to debris and other solid objects on sandy to muddy bottoms. The incubation period is dependant on temperature and is between 25 days (at 22°C) and 45 days (at 12 to 14°C). The size of the male determines the number (up to 800) and size of spermatophores. Males that are reproducing for the second time usually carry more than those reproducing for the first time.

• Egg mass

• Embryo

• Embryo

• Juvenile

Growth in both sexes is temperature dependant and is therefore faster in summer than in winter; the males grow faster than females. In the Atlantic, young squid hatched in June reach a mantle length of around 12 cm by December and grow to 13 or 14 cm by the following April. By August, males attain a mantle length of 17.5 cm and, if they reach the following April, 21 cm, compared to 17 cm in females. Life expectancy is 2 years in females and about 3 years in males.

European squid are predators on fishes and crustaceans. Cannibalism is common.