Resumen

TASCHERI O., Renzo  y  CLARAMUNT Q., Gabriel. An aproach to intra-anual changes in the energy contents of the ovary of south american pilchard (Sardinops sagax Jenyns, 1842) in northern Chile. Investig. mar. [online]. 1996, vol.24, pp.51-66. ISSN 0717-7178.  http://dx.doi.org/10.4067/S0717-71781996002400005.

Ovary and yolked oocytes modal dry weight of mature females of south American pilchard, distributed in two total length strata (300 females of 26-28 cm and 327 of 28-30 cm), was estimated on a monthly basis in northern Chile (19º-22ºS) during the reproductive cycle (between april'92 and march`93). The estimates were obtained using a Weibull function which relates the oocyte diameter to its dry weight, given the wet weight of the ovary, the wet weight of the subsample of ovarian tissue for the fecundity estimates and the oocyte diameter frequency distributions. The estimated variables fluctuations were related to monthly estimates of fecundity, oocyte average size for the more advanced batch, condition index, spawning frequency and the fraction of spawning females for the same reproductive cycle. The estimated ovary and yolked oocytes modal dry weight followed the same trend as the asymptotic oocyte dry weight and batch fecundity, with high values for the two spawning periods (winter and summer) and low values for the periods of less reproductive activity. A low fecundity and asymptotic oocyte dry weight value occurred in july along with a low value in the condition index by length stratum. A possible related effect to El Niño phenomenon is discussed.

Palabras clave : reproductive energy; oocyte; dry weight; yolk; ovary; pilchard; northern Chile.

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