Inventory, monitoring and impact assessment of marine biodiversity in the Seri Indian territory, Gulf of California, Mexico

Abstract

The conservation of marine ecosystems is at least 20 years behind terrestrial and freshwater ecosystems due to the difficulties in studying and monitoring these dynamic and complex environments. Furthermore, marine environment receive less attention because human impacts are less visible in the sea, and oceans are viewed as global commons. The purpose of the present dissertation is to contribute to the knowledge of marine conservation through the development of three components in natural resources management: inventory, monitoring, and assessment of impacts. I elaborate a multi-taxa inventory, identify key species to monitor, characterize one of the key species, and assess the impacts of the most important fishery in the community-based controlled marine area of the Seri Indians along the Sonoran desert coast of Mexico. A total 657 species of mollusks, echinoderms, sharks, rays, bony fish, sea turtles, sea snake, aquatic birds and marine mammals were recorded in the Seri territory through review of 30 scientific collections housed in museums and universities, literature, and field collections. The fish information was improved through the analysis of 151 traditional Seri names. Fifty species were identified for monitoring ecosystem health. They represent species with a legal status, rare, commercially important, taxa that dominate or characterize entire communities, common taxa, and species recognized in the Seri culture. The annual eelgrass (Zostera marina atam) was selected as a key species inside the Canal de Infiernillo in the Seri territory. Coverage of the eelgrass beds was estimated using aerial photographs, field mapping, and Seri traditional ecological knowledge. The total extent of the eelgrass beds was approximately 6687 ha, which regrew in the same areas during the three-year study, maintaining the same general shapes and sizes. Twenty-six percent of the eelgrass beds overlap with the swimming crab (Callinectes bellicosus) fishing zones. Major impact on this fishery are caused by "ghost" fishing traps, which continue to capture crabs and animals and modify the substrate as they are moved around by currents and accumulate on the sea bottom. Efforts to standardize the use of traps will reduce these impacts on this fishery in the long term.