Resumo

CASARIEGO-MADORELL, Ma. Antonieta; LIST, Rurik  e  CEBALLOS, Gerardo. Tamaño poblacional y alimentación de la Nutria de río (Lontra longicaudis annectens) en la costa de Oaxaca, México. Acta Zool. Mex [online]. 2008, vol.24, n.2, pp.179-199. ISSN 2448-8445.

The neotropical river otter (Lontra longicaudis annectens) is threatened in Mexico, and in order to design sound conservation strategies for its conservation, basic studies on their biology and ecology are necessary. The diet and abundance were evaluated between July, 1999 and August, 2000 in the rivers Ayuta, Copalita and Zimatán in the coast of Oaxaca. We considered estimated of four otters in 147.5 km the river Ayuta. 86 otters in 330.75 km the rive Copalita and 177 otters in 228.85 km the river Zimatán. We found a relation in an indirect way between the abundance of the otter and dissolved O₂. From 330 scats it was determined that they use four prey categories, which include crustaceans (53.0 ± 3.6%), fish (33.1 ± 9.9%), insects (9.8 ± 7.6%) and amphibians (4.0 ± 3.3%). In relation to the biomass ingested, the main prey were Macrobrachium americanum, M. acanthochirus and Gobiexos mexicanus. The largest number of fish and crustaceans used was obtained in the river Zimatán (n = 258 samples, 16 spp.) followed by the river Ayuta (n = 253, 14 spp) and the river Copalita (n = 197, 16 spp). We found a relation among the frequency of appearance of prey species in the scats, with their abundance (p < 0.01; r² = 0.40), as well as a significant relation between the consumed biomass and the abundance of the prey. Abundance of prey is determined by O₂ dissolved in the water (p = 0.04; r² = 0.09) as well as turbidity (p = 0.04; r² = 0.22). There was no relation between the physiochemical variables of the water with the diversity of the potential prey.

Palavras-chave : Lontra longicaudis; abundance; diet; biomass; river; Oaxaca.

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