Dusky Grouper: Where and when to dive with them

When diving for Dusky Groupers, maintain a calm and slow approach; abrupt movements can scare them back into their shelters. Look for them in rocky crevices, under ledges, and inside caves or wrecks. They are often found solitary. Spotting cues include their camouflaged, mottled brownish-grey coloration which helps them blend into rocky backgrounds. They can sometimes be identified by their prominent lower jaw and large, slightly protruded eyes. If you find one, remain still and observe from a distance; they are generally not shy once divers are perceived as non-threatening. Never harass or chase a grouper, as this can cause undue stress and disrupt their natural behavior. Flash photography can startle them, so use it sparingly or with caution. Be aware that this species is considered vulnerable to endangered in many parts of its range, particularly in the Mediterranean, due to overfishing. Therefore, it is crucial to observe a strict no-touch policy and adhere to all local regulations regarding marine life protection. In some areas, spearfishing is strictly prohibited or heavily regulated, so be mindful of local laws before diving with spearguns. Always dive responsibly and safely, respecting the marine environment.

Encounters with Dusky Groupers are often best during the warmer months when they are more active and closer to shore for feeding and breeding. In the Mediterranean Sea, late spring through early autumn (May to October) offers the highest chances of sightings, with July and August being peak months in areas like Sardinia, Italy, and the Balearic Islands, Spain, due to favorable water temperatures and increased fish activity. For locations off the Portuguese coast and the Canary Islands, summer and early autumn (June to November) are also highly productive. In the South Atlantic, specifically off the coast of Brazil, the warmer seasons (December to May) align with their reproductive cycles when they can be found in higher densities. During these periods, they are more frequently observed outside their shelters, making them easier to spot.

The Dusky Grouper, *Epinephelus marginatus*, is a demersal fish inhabiting rocky reefs, caves, and wrecks in temperate and subtropical waters of the Eastern Atlantic, Mediterranean Sea, and parts of the Indian Ocean. In the Mediterranean, particularly around Italy, Greece, and Croatia, they favor structured environments from shallow coastal waters down to depths of 200 meters. Off the coast of Portugal and the Canary Islands, they are commonly found in kelp forests and on rocky ledges. In the South Atlantic, their range extends to the coasts of Brazil, Uruguay, and Argentina, where they seek shelter in rocky outcrops and submerged caves. Juveniles typically inhabit shallower, more protected areas, gradually moving to deeper, more exposed reefs as they mature. They are often seen solitary, guarding their territories within their preferred shelter, especially larger individuals.

Dusky Groupers are opportunistic predators with a varied diet, primarily consisting of fish, crustaceans, and cephalopods. Their hunting strategy is characterized by ambush predation. They typically lie in wait, concealed within their rocky crevices or among kelp, before launching a sudden, rapid attack on unsuspecting prey. Common prey items include various reef fish such as damselfish and small wrasses, as well as crabs, lobsters, and octopuses. They use their large mouth to create a powerful suction, drawing in their prey whole. Juveniles tend to feed on smaller invertebrates and fish, gradually expanding their diet to include larger prey as they grow. They are not particularly selective and will consume almost any suitable prey that comes within striking distance.