A comprehensive study of the life history traits of Trematomus newnesi (Pisces, Notothenioidei) from the South Shetland Islands

Abstract

Understanding the life history traits of Antarctic fish species is crucial for effective management and conservation efforts purposes. This study provides a comprehensive evaluation of the reproductive dynamics and age-growth characteristics in Trematomus newnesi, a common notothenioid species in the High-Antarctic zone. Field observations conducted in Potter Cove, South Shetland Islands, revealed significant variations in photoperiod and water temperature from November to March, with water temperatures reaching a peak in mid-December. Gonadal morphology showed an exponential increase in gonadosomatic index in females and males from November to March, indicating ovarian and testicular development. Sex steroid plasma levels, particularly testosterone (T) and estradiol (E2), showed significant variations, with elevated levels observed during late vitellogenesis, suggesting the proximity of final maturation and spawning. Age estimation through otolith readings provided a range of ages up to five years old for both sexes. Comparison with previous studies on T. newnesi from other Antarctic areas highlighted similarities and differences in reproductive patterns and growth parameters, respectively. Our study suggests that temperature fluctuations, in conjunction with photoperiod, may act as triggers for reproductive events in T. newnesi starting in early autumn at Potter Cove. The environmental cues and reproductive data indicate that Potter Cove might serve as a spawning ground for T. newnesi. Likewise, larval hatching was estimated to occur from early to mid-August, suggesting an egg incubation period of four months. Overall, this study provides insights into the reproductive dynamics and life history traits of T. newnesi, as a valuable contribution for appropriate management and conservation of Antarctic fish populations.