Spatial modelling for freshwater cage location in the Presa Adolfo Mateos Lopez (El Infiernillo), Michoacán, México

Abstract

The tilapia ¢shery in a large Mexican reservoir has declined in recent years, promoting eiorts to enhance stock quality in conjunction with feasibility studies for cage aquaculture. Spatial models to optimize cage location have been developed, incorporating aspects of topography, climate, hydrography, water quality and quantity, land use, infrastructure and socioeconomics. Three cage sizes were modelled, 5, 10 and 15 m diameter, for both high- and low-water levels. When full the, reservoir has a total area of 312 km 2 but a reduction in water level of 13 m was recorded between wet and dry seasons, signi¢cantly reducing the surface area available for cages to 265 km 2 . The results indicate a signi¢cant diierence in the availability of sites between seasons. For the small, medium and large cages at high water level, the areas classi¢ed as highly suitable or suitable were 151, 184 and 146 km 2 , respectively, while at low-water level these areas reduced to 113, 88 and 62 km 2 . Modelling this change in water level and the subsequent loss of available sites provide qualitative and quantitative guidelines for the development of aquaculture sites, their seasonal management and future monitoring, outcomes that can only be achieved using Geographical Information Systems and associated technologies.