| Summary: | Boletín IMARPE vol. 31, nº 1, 2016; p. 89-97 Se describen los resultados de algunos aspectos de la biología y ecología del krill antártico Euphausia superba a lo largo del estrecho de Bransfield y alrededores de la isla Elefante (Primera Fase) y entre las islas Elefante y Clarence (Segunda Fase), obtenidos del 17 al 23 de enero 2007 a bordo del BIC Humboldt. Se efectuaron 25 lances experimentales de pesca: 13 correspondieron a la primera fase y 12 a la segunda. La captura total fue 6.852 kg, el 99% fue krill antártico. La distribución vertical del krill antártico estuvo entre 25 y 50 m de profundidad en el estrecho de Bransfield; en las islas Elefante y Clarence, se localizaron a mayor profundidad (50-75 m). La estructura por tamaños de E. superba mostró dos modas marcadas, una conformada por individuos sub adultos (43 mm de longitud total-LT) y otra por juveniles (28-30 mm LT). Por zonas, los juveniles fueron representativos en el estrecho de Bransfield y en el Frente oceánico; en tanto que los adultos (principalmente hembras grávidas) con mayor peso corporal se encontraron en las islas Elefante y Clarence. Entre las 04:00 y 12:00 horas los ejemplares estuvieron moderada e intensamente alimentados; mientras que, entre las 16:00 y 20:00 horas ligeramente alimentados. La dieta del krill estuvo constituida por elementos fitoplanctónicos (diatomeas, dinoflagelados y tintínidos). No se observó diferencias notables de la dieta del krill respecto a los tamaños, horas del día y profundidad de captura. ABSTRACT: Results are described of some biological and ecological aspects of the Antarctic krill along Bransfield Strait and Elephant Island (First phase) as well as between Elephant and Clarence Islands (Second phase), conducted on board the RV Humboldt from January 17th to 23rd 2007, with the goal to know the distribution, size composition, sex ratio, length-weight, feeding intensity and diet. Twenty-five fishing hauls were made: 13 were for the first phase and 12 to the second. The total catch was 6,852 kg of which 99% corresponded to Antarctic krill. The vertical distribution was shallow between 25 and 50 m of depth; otherwise on Elephant and Clarence Islands were located deeper (50-75 m). The size structure of E. superba showed two modes, one of them made up by sub adult individuals (43 mm of total length-TL) and juveniles (28-30 mm TL). By areas, juveniles were representative in Bransfield Strait and Ocean Front whereas, adults’ mainly gravid females with higher body weight were found at Elephant and Clarence Islands. Between 04:00 and 12:00 hours, individuals were moderate and intensively fed while between 16:00 and 20:00 hours, slightly fed. The krill diet was constituted by phytoplankton elements (diatoms, dinoflagellates and tintinnids). No significant differences were observed in the krill diet regarding the sizes, time of day and depth of catch.
|
|---|