Study on reproductive potential of Champsocephalus gunnari, Chaenocephalus aceratus, Pseudochaenichthys georgianus and Notothenia rossii from South Georgias Islands, March 2023

The aim of this study is to analyse the reproductive potential of icefish species (Champsocephalus gunnari, Pseudochaenichthys georgianus, Chaenocephalus aceratus) and Notothenia rossii off the coast of South Georgias. The research involves assessing length at maturity, total and relative fecundity, and relationships between oocyte size and maternal characteristics. The results show that C. gunnari, C. aceratus, P. georgianus and N. rossii are within their respective reproductive seasons. The length at maturity could only be estimated for C. gunnari and C. aceratus, whose values, obtained from combining both sexes were 30 cm TL and 43.7 cm TL, respectively. C. gunnari total fecundity (TF) showed a potential fit to size and a lineal fit to weight and ranged from 2,291 (27 cm TL) to 15,923 (49 cm TL) hydrated oocytes. It did not show significant differences with the values obtained in 2013. TF values for C. aceratus showed a lineal fit to size and weight, they ranged between 7,076 (53 cm TL) and 13,706 (67 cm TL) hydrated oocytes. N. rossii TF was powerfully related to female length and linearly related to weight, it ranged between 5,167 (45 cm TL) and 50,908 (66 cm TL) hydrated oocytes. Mean relative fecundity (RF) values were 22 oocytes/g for C. gunnari and 7-8 oocytes/g for C. aceratus and N. rossii. In the case of C. gunnari and C. aceratus the RF decreased with increasing length and weight of the females, while N. rossi showed the opposite relationship. Dry weight of C. gunnari and C. aceratus hydrated oocytes showed a positive relationship with female size. The manuscript's findings contribute to understanding the reproductive ecology of these species, highlighting their diverse strategies for survival and reproduction in the southern oceans. These insights are crucial for both ecological understanding and the sustainable management of fisheries resources.