The Dusky Grouper

Text: Nuno Vasco Rodrigues
Photos: Athila Bertoncini¹

One of the most emblematic fish species of the Iberian coasts is the Dusky Grouper (Epinephelus marginatus). The Dusky Grouper is part of the serranids family, such as groupers. It's characterized by being a relatively sedentary and territorial animal that occurs especially in areas of rocky bottom, taking refuge in caves, and being also common among shipwrecks. It's exclusively carnivorous, feeding on fish, cephalopods and crustaceans. This is a species of considerable longevity (maximum age reported is 50 years), reaching about 150 centimeters long and 60 Kilograms in weight. Sexually, it's characterized by being a sequential hermaphrodite, in other words, has the two sexes but they mature at different times. In the case of the Dusky Grouper, this is a protogynous hermaphrodite species, in other words, they are initially female and become male at some point in life.


Juvenile Dusky Grouper

Their geographical distribution is not limited to the Iberian Peninsula. Also occurs in the Mediterranean, Eastern Atlantic from the British coast to South Africa, Eastern Indian, and also on the Brazilian south coast. In Portugal they are relatively common in the Azores and Madeira, being less abundant in the continent.

Their sedentary lifestyle leads them to settle down, sometimes for several years, in specific locations, such as caves and shipwrecks. Such leads many dive centers to carry out immersions in order to observe these beautiful animals that are curious and often approach the divers. One of these examples known in Portugal is the Common Tern Natural Reserve, in Madeira.

The curiosity shown by these fish is one of the reasons for the inclusion in the current IUCN Red List with the status of "threatened." The fact of being a species highly appreciated for human consumption in some European markets such as Spain, Italy, France and, at a smaller scale, in Portugal, makes it very interesting as a fishing resource. His capture by underwater hunters is relatively common because of their curious characters and the dimensions that reaches. This activity is prohibited in the Azores, however, is permitted to catch by other fishing gear. Another factor that contributes to the decline in the Dusky Groupers populations is the direct cause of habitat destruction, often associated with human activity.

This situation of vulnerability and population decline is worrisome but easily explained, if to this we associate, among other factors, their sexual characteristics. The fact that this species become male only from a certain point in life, makes it essential to let the species grow, at the risk of having a population composed only by females, compromising their sustainability.


Adult Dusky Grouper

Nonetheless, there are many inherent characteristics of this fish that are still unknown. Ensure that scientific studies continue to be developed to increase knowledge about this species will be one of the ways to ensure their survival

Note
¹ http://athilapeixe.com

Submited by: Nuno Vasco Rodrigues