Rocky Habitats

The rocky bottom is part of the infralittoral steps of the Adriatic, which spreads from the intertidal zone to the depth of thirty metres and is permanently covered by seawater. Preconditions of shaping a rocky habitat are strong sea currents and the biogenic hardening of the seabed which form the basis of this community.

(Octopus vulgaris, Cuvier, 1797)

Octopus

The life cycle of the octopus is short, from 12 to 15 months, sometimes up to two years. Due to them being cold-blooded animals, they spend their winters in sandy seabeds in the open sea at a depth from 80-100 m. During the summer, due to high temperatures, they leave the rocky coastal areas and retreat to deeper waters. Females reach sexual maturity at a weight of 600 to 1700 g and a size of 12 cm, while males reach sexual maturity at 350 g and a size of 10 cm.

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Octopuses have the ability to quickly change the colour of their body thanks to cells located in their skin (chromatophores) which can expand and contract in a few seconds. Colour changes of octopuses are connected with stress or their mood; when they are scared, they lose colour and become paler; when angry, they become red or even black. When they are relaxed, they are brown in colour, and when they sleep, they are yellowish. It is interesting to note that they sleep with their eyes open, only narrowing their pupils.

(Sparus aurata, Line, 1758)

Gilt-headed bream

The gilt-headed bream is one of the most represented cage-bred species and is unique in that it has a strong and well-developed jaw with multiple rows of teeth, which make crushing bivalves and molluscs easier. Its lifespan is 11 years, its maximum length is 70 cm (on average, it grows to about 33-40 cm) and its maximum weight is 17 kg. It is a hermaphrodite which changes its sex during its lifetime (so-called protandric hermaphroditism), which is why we call it the “queen of the sea”, as all larger individuals are female.

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During the spawning season, from the end of September to November, in search of deeper waters, the sea bream migrates from Venice and passes through Slovenia and Istria towards the south, representing the leading target species for fishing. However, it's only in the last decade that there has been an increase in the catch of wild sea bream. The reasons for the increase in the abundance of sea bream in the sea are climate changes (as sea bream is a eurythermal species that prefers warmer waters), escape from fish farms, and the cultivation of shellfish on farms, where they find abundant food and cause significant damage (destroying up to 90% of the yield).

(Dicentrarchus labrax, Line, 1758)

European bass

Another Croatian name for the European bass is “lubin” from the Latin “lupus”, meaning wolf, which depicts it as a predatory fish. It has a long jaw filled with sharp teeth for catching fast and mobile prey. It feeds primarily on crustaceans, shrimp, molluscs and fish. Males reach sexual maturity at two years of age or when they are between 23 to 30 cm long, females at around 3-4 years of age or between 31 to 40 cm in length.

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Did you know that temperature and salinity are the main oceanographic parameters that determine the sex of sea bass? In the natural environment, the sex ratio of sexually mature individuals ranges from 52% to 69.5% females compared to males, while in hatcheries, this ratio is 75% to 95% males compared to females. Sea bass can tolerate a wide temperature range from 8 to 24°C and a broad range of salinity levels.

(Diplodus vulgaris, Geoffroy Saint-Hilaire, 1817)

Common two-banded sea bream

Fratar je najbrojnija pridnena riba kamenitih staništa koju krase dvije crne mrlje; na škržnom poklopcu i kod repne peraje. Kao i sve vrste iz porodice ljuskavki (Sparidae), dvospolac je koji mijenja spol ovisno o veličini. U Jadranu je rasprostranjena uzduž cijelog obalnog pojasa, a najčešće je možemo pronaći uz zapadnu obalu Istre.

Did you know the common two-banded seabream is considered a long-lived species in the Adriatic Sea? Females, in particular, can live up to 11 years, reach a weight of up to 797g, and have a body length ranging from 14.5 to 37.5 cm. On the other hand, males have a shorter lifespan, usually up to 10 years, with a body length ranging from 14.5 to 36.2 cm and a weight of up to 760 g.

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