Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

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Reproductive aspects of Galaxias platei (Pisces, Galaxiidae) in a deep lake in North Patagonia

Daniela Milano , Juan Barriga

Abstract

Reproductive characteristics of the native fish G. platei were studied in Lake Moreno, an ultra-oligotrophic deep lake in North Patagonia. According to histological analysis of ovaries, G. platei presents the synchronous oocyte development typical of a group-synchronous spawner. Mature oocyte diameter ranged from 1031 to 1419 μm. Based on the gonadosomatic index, annual spawning occurs between autumn and early winter (March-June), and is directly related to the water temperature of deeper strata (below 30 m), where this species lives, but not with photoperiod. Females of G. platei acquire sexual maturity at 105 mm length, while males do so at 177 mm length. Delaying maturity to obtain higher fecundity, as well as maximum body size and longevity, indicates that G. platei is more specialized than the other South American Galaxias, G. maculatus, in terms of lifestyle. These specialized features are related to the stable environment it lives in, and indicate that G. platei could eventually become a vulnerable species in unstable environments, such as the Patagonian lakes dominated by salmonids.

MF17304  Accepted 01 February 2018

© CSIRO 2018