Reproduction in puyen, Galaxias maculatus (Pisces: Galaxiidae), in the southernmost extreme of distribution

Abstract

Reproductive aspects of a peripheral population of Galaxias maculatus are described and the relationship with the physiology and handling of energetic reserves under marginal environmental conditions is investigated. The G. maculatus population of Tierra del Fuego has an extended reproductive season, with differences in timing and duration compared to other populations of continental Patagonia, New Zealand and Australia. Elevated gonadosomatic indexes (I G ) were observed during this period in both sexes (maximum I G ¼ 33.49% males; 35.94% females). The high abundance of mature males (with high I G values) on the spawning grounds during the reproductive season suggests that they were waiting for the return of the mature females. Larger females reached total maturation at the beginning of the reproductive season, whereas the size of maturing females diminished toward the end (mean TL ¼ 96 mm, October; 70 mm, February). Both sexes showed an extremely high investment in reproduction, reaching a maximum I G of about 35% for both sexes. At the beginning of the reproductive season females reached the maximum median I H (3.37%) and males the minimum (0.96%), suggesting differences in the role of the liver in the management of energetic reserves during sexual maturation. The variation in the fat index (I F ) suggests that fat reserves were used to survive winter (maximum median I F > 1%, autumn; minimum about 0.2%, spring).

Reproductive biology ofGalaxias maculatus(Jenyns 1842) in the Río Ovando, a high-latitude environment in southernmost Patagonia, Argentina

“…At an individual level there is a trade‐off between feeding and oocyte production, given the limited peritoneal space for the mature ovary; as a consequence ripe females generally do not feed. In high latitude environments the photoperiod and temperature restrict the favorable period to a few spring/summer months when populations must concentrate their reproduction, as was found previously in this population (Boy et al., 2007). Moreover, during summer these Fuegian puyen also allocate high amounts of energy towards overwinter (Boy et al., 2008), having an extra demand of energy during a shorter period than other puyen populations at lower latitudes.…”

“…Summarizing, the reproductive biology of G. maculatus differs greatly between populations. Different timing and duration of the reproductive season, different spawning strategies and different fecundity were found (McDowall, 1968; Campos, 1970; Ferriz, 1987; Peredo and Sobarzo, 1994; Barriga et al., 2002; Chapman et al., 2006; Boy et al., 2007). This high plasticity in the life‐history of G. maculatus explains the species’ worldwide distribution (Barriga et al., 2007) and allows the puyen to inhabit very different habitats.…”

“…It has been suggested that its great life history plasticity could be the key to explaining the wide distribution of the species in the southern hemisphere (Barriga et al., 2007). This plasticity is related to maximum size (Barriga et al., 2007; Boy et al., 2007), seasonality, length of the spawning season and reproductive strategy (McDowall, 1968; Pollard, 1971; Chapman et al., 2006), allocation of energy in different organs (Boy et al., 2008), and to the feeding of larvae at sea or in lakes (Ferriz, 1987; Peredo and Sobarzo, 1994).…”

Intraspecific variation in diet, growth, and morphology of landlocked Galaxias maculatus during its larval period: the role of food availability and predation risk

“…This galaxiid fish has a plastic life history including landlocked and diadromous populations (McDowall, 2002(McDowall, , 2003Chapman et al, 2006;Barriga et al, 2007;Boy et al, 2007). Lacustrine landlocked G. maculatus populations have a larval period during which individuals spend up to 6 months in the limnetic zone of lakes (Cussac et al, 1992;Barriga et al, 2002).…”

Reproduction of landlocked Aplochiton zebra Jenyns (Pisces, Galaxiidae)

“…2004). Breeding season also varies between landlocked and diadromous populations and within these groups along the geographic range (Boy et al. 2007).…”