Reproductive aspects of Galaxias platei (Pisces, Galaxiidae) in a deep lake in North Patagonia
DANIELA MILANO; JUAN PABLO BARRIGA
MARINE AND FRESHWATER RESEARCH
Lugar: Collingwood; Año: 2018 vol. 69 p. 1379 - 1388
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 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 April and June (austral autumn) 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 G. platei lives in and indicate that it could eventually become a vulnerable species in unstable environments such as the Patagonian lakes dominated by salmonids.