Goldblotch grouper

Goldblotch grouper, Epinephelus costae is a common grouper species found in the southern Mediterranean Sea. It’s usually found from Rome onward, where it’s also called “Dotto” (literally, “Doctor”) for its proverbial cunning. In this video, however, we’re in a shallow halfway between the island of Gorgona and Livorno, where we’ve never seen it before.

What we’ve seen here is actually a juvenile, about 40-50 cm long and weighing a few kilograms. It’s characterized by its dark coloration and horizontal stripes of golden spots, typical of juveniles. As it grows, its coloration becomes golden.

We’ve already encountered this splendid fish in Sardinia and other southern Mediterranean islands; this is another sign that the Mediterranean Sea is indeed warming quite rapidly. The water temperature at about 45-50 meters depth was 21°C, and the presence of mucilage at a distance of 9 nautical miles from the coast is another example.

The northward migration of these species, which we have frequently documented on intotheblue.it, should make us reflect on the fact that global warming is still ongoing and will be difficult to halt or stem in the short to medium term.

It is an extremely wary species of humans, making it difficult to approach and photograph. This wariness, and the fact that it is quite rare, has earned it the nickname “Dotto.” According to the IUCN (International Union for Conservation of Nature), it is classified as vulnerable because, like other grouper species, fishing is the primary threat, particularly trawling and underwater fishing, as well as habitat destruction.

Goldblotch grouper or also ductus (Epinephelus costae) is a sea fish of the Serranidae family.

Distribution and habitat

It is a southernmost species of the most common and well-known brown grouper, in fact in the Atlantic it is not found further north than the gulf of Cadiz while to the south it reaches South Africa. In Italian waters it is more common along the coasts of the southern regions. It lives on mixed funds of sand and rock with prevalence of the latter.

Description

It has a more elongated shape and a lower jaw that is more prominent than the brown grouper but it is recognized above all for the coloring, which however goes through various phases:

• normal livery: golden yellow spot behind the gill operculum, four parallel horizontal dark lines on the back, on a beige background;
• young: there are more than four lines on the sides, no golden spot on the side;
• adult male: golden stain clearly visible and extended lower half of the whitish body surmounted by a very dark irregular band.

The dimensions reach 80 cm per 8 kg of weight.

Supply

Identical to that of the brown grouper.

Biology

It is more gregarious than the other groupers and can live in small herds. Young people are sometimes extraordinarily friendly and show no fear of divers while adults are very suspicious.

https://it.wikipedia.org/wiki/Epinephelus_costae

Gallery

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