Spatial and temporal distribution of landlockedGalaxias maculatusandGalaxias platei(Pisces: Galaxiidae) in a lake in the South American Andes

Abstract

Galaxiids are present in many of the Andean lakes in southern South America. We studied landlocked Galaxias maculatus (Jenyns) and Galaxias platei Steindachner populations in a deep oligotrophic lake (Lake Gutiérrez, Patagonia, Argentina). Their temporal and spatial distribution, intralacustrine movements (horizontal and vertical), and spawning periods were analysed using several sampling techniques (ichthyoplankton net, seine net, gill net, and baited benthic taps). We identified the early life stages of both species based on their morphology and otolith shape. The free embryos of both species migrate to the limnetic zone, where they coexist as larvae, facing the same food availability and probably the same predation risk. Each species then moves on to its own juvenile and adult habitat: the littoral and benthic zone for G. maculatus and only the deeper benthic zone for G. platei. Their adult habitats and part of their spawning periods partly overlap.

Relación longitud-peso y factor de condición de los peces nativos del río San Pedro (cuenca del río Valdivia, Chile)

“…Sin embargo, no existen antecedentes de los períodos reproductivos y fechas de postura que nos permitan asociar este máximo a un estado pre-desove de los individuos. Barriga et al (2002) señalan un período de pre desove para el mes de diciembre en poblaciones de lagos patagónicos Argentinos. Cussac et al (2004) señala la presencia de larvas para la época estival en lagos argentinos.…”

“…Este hecho podría dar señal de un máximo de K relacionado a la "maduración" de gónadas durante verano. No obstante, uno de los datos relevantes entregado por Barriga et al (2002) es que sólo individuos capturados en profundidad, sobre 30 metros, en estos lagos se encontraban "maduros". Por ende, no poseemos antecedentes que nos permitan señalar concluyentemente que G. platei puede también reproducirse en ambientes lóticos, por lo cual es también probable que el máximo valor de K para esta especie sea producto de una respuesta a una mayor disponibilidad de alimentos posterior a la época de deshielos de primavera.…”

Surface avoidance by freshwater zooplankton: Field evidence on the role of ultraviolet radiation

“…Visual planktivores in Patagonian lakes are mostly restricted to larval and juvenile fish (ichthyoplankton) usually galaxiid fishes Galaxias maculatus; Galaxias platei (Barriga et al 2002). As mentioned above, a major advantage of the studied environments is that they share the same crustacean zooplankton and ichthyoplankton assemblages.…”

Native and exotic fishes in a Patagonian reservoir with rainbow trout cage culture: spatial and trophic resource use

“…In the case of P. trucha, increased abundance of reproductive fish in shallow water is expected from spring to early summer (Buria et al, 2007;Aigo, 2010;Juncos et al, 2014), seasons we did not sample. However, our results showed an intense vertical segregation that suggests strong (Barriga et al, 2002(Barriga et al, , 2007Juncos et al, 2014), and more abundant terrestrial insects are expected in spring and summer (Juncos et al, 2014). Therefore, these changes would reduce the low incidence of G. maculatus in rainbow trout diet, and intensify its differences with P. trucha, as it consumes greater proportions of terrestrial insects, a prey group not generally important for P. trucha (Macchi et al, 1999;Juncos et al, 2014).…”