The Brown Grouper

Symbol of exemplary conservation

back on our shores after 30 years of effort

An icon for many scuba divers, both for its size (it is one of the largest bony fish in the Mediterranean) and its rarity, the brown grouper Epinephelus marginatus had almost disappeared after decades of overfishing and poaching. Thanks to strong protection measures, it is making a strong comeback in the waters of the French and Monegasque Mediterranean, especially in protected areas, allowing the underwater hiker to admire its unique and majestic behaviour. Watching it while diving is a privileged and magical moment, a memory that you will keep in your head for a long time! The return of the grouper is not a coincidence but the result of 30 years of efforts, an example that should inspire us to better protect endangered species in the Mediterranean! Explanations…

Male or female? Both of them! A little biology...

Enzo le petit mérou brun de Méditerranée relaché
A young brown grouper under its rock. Credit: Nicolas Robert.

The brown grouper lives between the surface and 50 to 200m depth, in the Atlantic Ocean (from the Moroccan coasts to Brittany) as well as in the whole Mediterranean Sea. It is also found off Brazil and South Africa, but researchers wonder if it is a homogeneous population or distinct subpopulations. The mystery remains today!

It likes coastal rocky habitats rich in crevices and cavities. The juveniles, more littoral, are sometimes observed in a few centimeters of water. Its size varies from 80 cm to 1 m or even 1.5 m for the largest individuals.

The grouper changes sex during its life: “protogynous hermaphrodite”, it is first female then becomes male when it reaches 60 to 70 cm, at the age of 10 to 14 years.

Regulator and indicator of the state of the marine environment

A super-predator at the top of the food chain, the grouper hunts its prey (cephalopods, crustaceans, fish) at lower trophic levels, thus playing the role of regulator and contributing to the balance of the ecosystem. It is also an indicator of environmental quality. The abundance of groupers reflects the good condition of the food chain that precedes it, the presence of rich food and the expression of moderate poaching and fishing pressure. Because of its very high commercial value, brown grouper remains highly sought after by fishermen and spearfishermen throughout its range. Its numbers are in sharp decline and it is classified by the International Union for Conservation of Nature as a

vulnerable species.

Did you know?

8 species of groupers are present in the Mediterranean. Among the 6 species observed in Monaco, the brown grouper Epinephelus marginatus is the most frequent, then comes the impressive wreck grouper Polyprion americanus. The canine grouper Epinephelus caninus, the badèche Epinephelus costae, the white grouper Epinephelus aeneus, the royal grouper Mycteroperca rubra are much more discrete.

Mycteroperca rubra
A group of the rare king grouper Mycteroperca rubra in the Scandola Nature Reserve. Credit: Jean-Marie Dominici.
Cernier-Polyprion americanus (Y.Berard)
The cern or wreck grouper Polyprion americanus.
Le Mérou bardèche
A badger grouper

The Grouper in pictures

The protection of the grouper, it works!

The increasing scarcity of this fish has led France and the Principality of Monaco to adopt strong protection measures within the framework of international conventions (Berne, Barcelona). The


established in mainland France and in


since 1993 prohibits underwater hunting and fishing with hooks. Field studies show the effectiveness of these protection measures: young groupers are now present on all the coasts, and in the marine reserves the populations have recovered. But this comeback remains very fragile. The moratorium is to be reviewed every 10 years. The future of the grouper will therefore be decided in 2023. If hunting were to be allowed again, more than 30 years of effort could be wiped out in a few weeks!

Mérou brun M.Dagnino
A female brown grouper, at the entrance of its refuge on a coralligenous drop off.

In Monaco, the Sovereign Order of 1993, reinforced by the

ordinance of 2011

prohibits all fishing and ensures the protection of the brown grouper as well as the corb, another vulnerable species. Thanks to this specific protection, to the Larvotto Reserve and to the presence of very favourable habitats and abundant food, the brown grouper is once again abundant in the waters of the Principality of Monaco, particularly at the foot of the Oceanographic Museum.

Did you know?

Why do we still find brown groupers on the fishmongers’ shelves? Simply because the use of nets to catch them is still allowed. Specimens imported from unregulated areas may also be offered for sale. It is up to us as consumers to avoid buying endangered species!

The Principality takes care of the groupers

Since 1993, under the control of the Environment Department,
the Monegasque Association for the Protection of Nature
assisted by the
Grouper Study Group
is carrying out a regular inventory of groupers in Monegasque waters, from the surface to a depth of 40 m, with the natural participation of the divers from the Oceanographic Museum. From year to year, the numbers observed increase (15 individuals in 1993, 12 in 1998, 83 in 2006, 105 in 2009, 75 in 2012). Large specimens of 1.40 m are now numerous and juveniles of all sizes are observed on the shallows.

The grouper survey is done in small groups of snorkelers or divers.

the oceanographic museum also gets wet...

The Museum also comes to the rescue of specimens in difficulty that are entrusted to it by fishermen or divers, as was the case at the end of 2018, with several individuals affected by a viral infection, already observed in the past on several occasions in the Mediterranean in Crete, Libya, Malta, and Corsica. With the Participate in activities created in 2019 to care for turtles and other species, these interventions are now facilitated. The cured groupers return to the sea to be in protected areas such as the Larvotto Underwater Reserve. Watch the video of the release of the young grouper “Enzo”.

Enzo le petit mérou brun de Méditerranée relaché
The entire team before the release of a grouper, a moment to raise awareness among sea users about the status of this vulnerable species.
Enzo le petit mérou brun de Méditerranée relaché
The Director General of the Oceanographic Institute, Robert Calcagno, gives a young grouper its freedom, under the eye of cameraman Frédéric Pacorel.


Many visitors discover this heritage species at the Oceanographic Museum. This is not new, since the Aquarium, then directed by Doctor Miroslav Oxner, was already presenting them in 1920! One of them, now in the Museum’s collections, lived there for over 29 years. 4 different species (badèche, brown, white and royal grouper) are now visible in the section dedicated to the Mediterranean completely renovated.
If the grouper intrigues visitors, it also inspires artists! Numerous objects bearing his likeness, both works of art and manufactured objects, can be found in the collections of the Oceanographic Institute!
In 2010, a grouper from the Museum was used as a model for the 100 Reais banknote issued by the Central Bank of Brazil, which is still in circulation today, and the Principality even dedicated a postage stamp to it in 2018!

aquarelle réalisée par Paul Seguin-Bertault
A watercolour by Paul Seguin-Bertault (circa 1947) belonging to the Collections of the Oceanographic Institute.
Brasil Billet 100 reais
100 Reais note from the Central Bank of Brazil (courtesy of Mr. Marcia Barbosa Silveira).
roussettes mérou barba
Old postcard from the Oceanographic Museum showing a grouper tank

An asset for the blue economy, tourism and fishing...

Tourists come from far and wide to observe the underwater fauna and a “successful” dive is often one during which the brown grouper has been observed! Several studies show that a live grouper brings in infinitely more money during its existence than if it is caught to be consumed!
Brown grouper particularly thrive in effectively managed marine protected areas (MPAs), which provide important biodiversity conservation and economic development benefits. By protecting and restoring critical habitats (migration routes, predator refuges, spawning grounds, nursery areas), MPAs contribute to the survival of sensitive species such as brown grouper. Adults and larvae of different species living within an MPA can also leave it and colonise other areas, this is called Spillover. When the eggs and larvae produced in the MPA drift out, it is called Dispersal. Species with high market value (brown grouper, lobster, red coral) travel considerable distances, providing ecological and economic benefits in remote areas! Adult brown groupers stray one kilometre outside the MPA boundary. As for the larvae, they travel several hundred killometers!

See also