An analysis of precautionary management rules for trout aquaculture in Patagonian shallow lakes based on bird habitat preferences

LANCELOTTI JULIO LUCIO; LUCIANA M.ELINA POZZI; MIGUEL ALBERTO PASCUAL; MARÍA DEL CARMEN DIÉGUEZ; PABLO, M. YORIO

Maturín, Venezuela

Congreso; VIII Congreso de Ornitología Neotropical; 2007

Neotropical Ornithological Society y Unión Venezolana de Orniotología

Patagonia is endowed with some of the wildest landscapes on Earth. Most of the region´s ecosystems, however, are increasingly disturbed by human activities. A major challenge for freshwater conservation in Patagonia is to identify strategies that could preserve native biodiversity in the face of growing aquaculture based on exotic species. In the arid, extra-Andean Patagonia, a single plateau (“Strobel Meseta”, 48º50`S,71º20´W) holds over a thousand shallow lakes. This macroecosystem, devoid of native fishes, has a rich bird fauna, including the hooded grebe (Podiceps gallardoi), an endemic specie considered Near Threatened. In 1995, a few lakes were planted with rainbow trout, generating a growing aquaculture activity, as well as concerns about potential impacts on this unique ecosystem. We applied a multivariate analysis to a subset of representative fishless and trout lakes of the meseta (N= 32), in order to classify them based on topographic and limnological characteristics and to evaluate their importance as bird habitat. In addition, we carried out a generalized linear model analysis to relate hooded grebe presence/absence with selected lake variables. Lakes could be clearly sorted out into four types: shallow vegetated (SV), shallow unvegetated (SU), deep vegetated lakes (DV), and deep unvegetated lakes (DU). Birds predominantly occupy SV, SU, and DV lakes, and are rare in DU lakes. Hooded grebes clearly prefer DV lakes, where they are the most abundant. Lakes planted with trout largely correspond to the DU type, but an overlap exists in use and potential use with bird lakes of the DV type. We analyzed different rules to set lakes apart from aquaculture based on their characteristics, and identified precautionary rules that may ensure the conservation of prime bird habitat, while maintaining trout production.