Prospección aérea otoñal de toninas overas (Cephalorhynchus commersonii) en el estrecho de Magallanes
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1987
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Se informa de un censo aéreo mediante helicóptero del cetáceo delfínido tonina overa (Cephalorhynchus commersonii) efectuada en el otoño de 1987 en el sector oriental del estrecho de Magallanes. Se establecieron 42 transectas desde la segunda angostura hacia el oriente, completando un total de 577,5 Kms. lineales, sobre un área de 3.600 Km.2 La densidad se estimó con el método de transecta en línea, analizando la información mediante un programa computacional del estimador lineal no paramétrico de series de Fourier. Durante el período de muestreo se estimó para el área de estudio una densidad de 0,0765 (e.e. = 0,0241; N = 21) toninas por km,2 siendo mayor en los sectores angostos donde ésta asciende a 0,340 individuos por km.2 La abundancia numérica para toda el área de estudio fue de aproximadamente 313 ejemplares, al aplicar el factor promedio de grupo (1,14). Se comparan estos resultados con censos anteriores y se discute el significado de estas cifras.
An aerial census, from helicopter, of delphinid cetacean Commerson's Dolphin (Cephalorhynchus commersonii), carried out during tall 1987 on the eastern sector of the Strait of Magellan, is reported. 42 transects were flown between the Second Narrow and the eastern entrance of the Strait, totaling 577,5 kilometers over an área of 3.600 square kilometers. Estimation of density was made using line transect technique and the information was analysed through a computational program of the non-parametric lineal estimator of Fourier series. During the sampling period density for the whole study area was 0,0765 (s.e. = 0,0241; n = 21) dolphins per square kilometer, being higher in the narrowest sectors, where the density went up to 0,340 individuals per square kilometer. The numerical abundance of the whole study area was approximately 313 specimens, when the mean factor per group was applied (1,14). These results are compared with those of previous censuses and the significance of these values is compared.
An aerial census, from helicopter, of delphinid cetacean Commerson's Dolphin (Cephalorhynchus commersonii), carried out during tall 1987 on the eastern sector of the Strait of Magellan, is reported. 42 transects were flown between the Second Narrow and the eastern entrance of the Strait, totaling 577,5 kilometers over an área of 3.600 square kilometers. Estimation of density was made using line transect technique and the information was analysed through a computational program of the non-parametric lineal estimator of Fourier series. During the sampling period density for the whole study area was 0,0765 (s.e. = 0,0241; n = 21) dolphins per square kilometer, being higher in the narrowest sectors, where the density went up to 0,340 individuals per square kilometer. The numerical abundance of the whole study area was approximately 313 specimens, when the mean factor per group was applied (1,14). These results are compared with those of previous censuses and the significance of these values is compared.
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Tonina overa (Cephalorhynchus commersonii)
Citación
Anales del Instituto de la Patagonia, Vol. 17, pp. 69-75, 1987.