Inventory of groupers and brown meagres in Monegasque waters: report

As part of the Prince’s Government’s policy on protecting biodiversity, the Department of the Environment led its sixth campaign to take an inventory of dusky groupers (Epinephelus marginatus) in the Principality’s waters during October 2015.

The Department has carried out a qualitative and quantitative study of the grouper population every three years since 2006. The 2015 exercise also provided an opportunity to carry out a second inventory of the brown meagre population in the Principality.

These species, which are an important part of the country’s heritage, are protected. Catching them has been banned in the Principality since January 1993. The species also benefit from protection in French Mediterranean waters, through moratoria which are renewed every 10 years for the grouper and every five years for the brown meagre.
From 15 to 19 October, with logistical support from the Department of Maritime Affairs, 18 divers (including three free divers) from the Grouper Study Group (Groupe d’Etude du Mérou, GEM) and three divers from the Department of the Environment combed Monegasque waters from Fontvieille to Larvotto. The aim was to take a census of the populations of these species according to a protocol which has been used for a number of years, particularly in the Port-Cros National Park reserve.

The divers were divided into several teams. They combed the sites, moving in parallel at a distance of between 5 and 10 metres apart and recording the following information for each grouper: size, time of dive, depth, characteristics of habitat, behaviour and direction of movement. To avoid double counting, a report and review of operations were carried out by each team when they returned from their dives.

This time, 193 specimens measuring between 20 cm and 120 cm were counted. These figures show that there has been a sizeable increase in the dusky grouper population, which was 105 in 2009 and 83 in 2006. The brown meagre census also showed that there had been an increase in the population of that species, from 11 in 2012 to 25 in 2015, ranging in size from 15 cm to 70 cm.

According to this scientific study, the dusky grouper is found primarily in the zone located to the west of Port Hercule and the Spélugues coral reef area. The brown meagre is found mainly in the Larvotto reserve and in the area to the west of Port Hercule, which is home to the majority of individual fish.

The increase in the number of dusky grouper is marked by a change in the demographic structure of the population, with 58 juveniles observed. This is synonymous with local reproduction and proof that the protective measures taken in the Principality are effective.

The next inventory is scheduled for October 2018.