Dusky grouper - Epinephelus marginatus. (Photo: David Diaz / IEO)
New management measures to protect dusky grouper stocks
Thursday, February 21, 2013, 23:30 (GMT + 9)
A team of scientists from the Balearic Oceanography Centre of the Spanish Institute of Oceanography (IEO) and the Directorate General of Fisheries of the Balearic Government participated in a research on the factors that determine the distribution of the dusky grouper (Epinephelus marginatus) in Cabrera Archipelago Maritime-Terrestrial National Park.
Researchers wanted to see if the current Park management measures are adequate for proper conservation.
The dusky grouper is a keystone species of the rocky Mediterranean ecosystem and considered endangered by the International Union for Conservation of Nature (IUCN).
In the Park waters, the dusky grouper shows high densities compared to the rest of the Mediterranean.
The experts identified the optimal habitats for juveniles and adults of the species, and their movement patterns.
In addition, they estimated grouper population size at first maturity in the Park and the development of specific methods of capture to reduce the impact on this and other species in the study area, the IEO informed.
Scientists assessed the abundance and characterized the resource habitat by immersion census, while the study of the movement pattern was addressed through mark-recapture techniques.
The study results reveal differences in the spatial and temporal distribution of the population of juveniles and adults, and between breeding seasons and post-breeding.
The juveniles are distributed mostly in rocky areas of high roughness and low hydrodynamism at depths less than 18 meters. Meanwhile, adult groupers showed preference for stream areas on sloped substrate with small rocky stands and depths greater than 17 meters.
"These results show that spatial management measures currently in place in the park, such as the prohibition of fishing within 20 meters depth, and the location of integral wilderness areas in the bays, are optimal habitat protection for juvenile grouper, but they are not the preferred habitats of adults," the researchers explained.
"Accordingly, we have recommended the amendment of existing management measures and proposed a series of measures that include the protection of the essential habitat for dusky grouper throughout all the phases of its life cycle," they added.
These proposals are based on:
- The densities of dusky grouper populations;
- The abundance and diversity of other large groupers and vulnerable or threatened species;
- The diversity of benthic communities and underwater landscape quality;
- Surveillance capacity and fishing effort in each area.
The results of the project Identification of Movement Pattern and Environmental Factors that Determine the Spatial Distribution of the Dusky Grouper in Archipelago of Cabrera National Maritime-Terrestrial Park: Applications for Its Conservation were published by the Ministry of Agriculture, Food and Environment (Magrama) in the fifth volume of the series Research on the National Park Network, which aims to spread the results of the research projects funded by the National Parks Autonomous Agency
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