Life-history traits in the southernmost landlocked population of the fish Galaxias maculatus

ROJO, J.H.; BOY, C.C.

POLAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2022

0722-4060

Studying life-historytraits is critical to understanding the intraspecific variation among fish populations.In this research, we investigated the age, growth, and sexual maturity of Galaxias maculatus population from LagunaNegra (LN), the southernmost landlocked population of the species, and comparedthe results obtained with those obtained before for the diadromous population fromArroyo Negro (AN), 1.8 km away from LN. We read otolith growth bands toestimate age structure and calculated the gonadosomatic index to estimatesexual maturity. We found five age classes (0+ to 4+) in LN; the maximum agewas 4.5 years, the maximum documented age for the species, exceeding in oneyear the maximum age found previously for the AN population. Age class 2+ wasthe most represented throughout the year, and the greater age and length-at-ageratio observed in this landlocked population suggest a slower growth rate thanthat of AN. We hypothesize that landlocked individuals reach their first sexualmaturity one year later than their diadromous counterparts. The protractedreproductive season detected in this landlocked population (9 months) may berelated to the high size variability within age classes, where some individualsmight maximize growth while others might maximize first sexual maturity. Ourresults suggest higher energetic costs for these basic biological activities inlandlocked than diadromous populations from Tierra del Fuego, Argentina.Further studies are necessary to understand the trade-off between growth andsexual maturation in sub-Antarctic G. maculatuspopulations.