The grouper, an iconic Mediterranean fish, has almost disappeared from our coasts as a result of spearfishing. It is considered by the International Union for Conservation of Nature (IUCN) to be an endangered species and, like the brown meagre, has enjoyed protected status in the Principality since 1993.
To assess the population dynamics of dusky grouper and brown meagre and determine how effective the protection measures are, the Department of the Environment turned to the Groupe d’Étude du Mérou (GEM, Grouper Working Group), which developed techniques for counting these species more than 30 years ago.
The GEM is a French organisation which was founded in December 1986 by enthusiasts and scientists seeking to understand the reasons behind the disappearance of the dusky grouper in the early 1980s. Today, the group comprises around a hundred active or corresponding members across the world.
In 2006, the Department of the Environment introduced monitoring in partnership with the GEM. This is now carried out every three years along the Principality’s entire coastline. Following the sixth monitoring campaign, to be carried out in October, 15 years worth of data will be available on these populations.
The approach to counting used in the GEM campaigns aims to be as exhaustive as possible in terms of covering the relevant areas. Divers are split into two teams and move in parallel, a few metres from each other, depending on the topography of the sites and on visibility conditions. Each time they encounter a grouper or brown meagre, various details are noted: size (total length, estimated to the nearest 5 cm), species (a mottled grouper, for example, was recently observed during another study), dive time, depth, habitat characteristics (rock, grass, scree, rock cavity, drop-off, etc.), the behaviour of the fish (fled, indifferent, in a hole or in open water), and the direction of travel if movement was noted.
The campaign, which is taking place from Thursday 7 October to Tuesday 12 October 2021, will involve some 15 divers from the GEM and the Department of the Environment. Divers from the Oceanographic Museum, the Monegasque Association for the Protection of Nature and the Monaco Scientific Centre are also taking part in the campaign and the Department of Maritime Affairs is making maritime resources available.