Unveiling growth and reproduction of a giant Patagonian galaxiid: an experimental rearing study

ABSTRACT

Understanding the life history of understudied native and threatened fishes is crucial to develop conservation strategies for freshwater ecosystems. Puye grande (Galaxias platei) is an endemic freshwater fish of Patagonia with little known about its life history traits. To bridge this information gap, comprehensive studies under controlled conditions could expand our basal understanding of puye grande’s life history. We conducted a long-term experimental study using one cohort of puye grande throughout its lifespan. We collected 423 postlarvae individuals from the Riñihue Lake (southern Chile) and reared them for 11 years under captivity. We documented the maximum longevity of this species as 11 years, with a survival rate of 0.47% for the entire study period. Hatchery-reared individuals showed isometric growth (b = 2.75). Parameters of the von Bertalanffy growth model were asymptotic total length L_∞ = 20.80 cm, growth coefficient K = 0.75 yr⁻¹, and theoretical age at-length zero t₀ = 0.45 yr, including both sexes. Puye grande showed an iteroparous life history, with the first spawning event occurring at age 2+ and consecutive spawning events occurring mainly in fall and winter. Females had a mean (standard deviation) total fecundity of up to 58 500 (23 331) eggs individual⁻¹ and a mean relative fecundity in fall of 621 (109) eggs g⁻¹ wet mass; males had a mean spermatic density of 28.41 (4.18) × 10⁹ spermatozoa mL⁻¹. The embryonic development until eclosion occurred 432 h post fertilization (hpf) at 12 °C. Our valuable baseline findings about the life history of puye grande can contribute to future strategies for managing and conserving galaxiids under global environmental change in Patagonia.

KEYWORDS:

• freshwater fish aquaculture; Galaxias platei
• Galaxiidae
• native fishes
• Patagonia

Acknowledgements

Claudia Andrea Cossio Oyarzún and Tito René Lobos Álvarez helped during the study period. Erin Wight from the University of Maine helped edit this English edition.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical statement

The Catholic University of Temuco ethics committee reviewed and approved this study’s experimental procedures, which were conducted according to Chilean Law No. 20.380 for Animal Protection.

Additional information

Funding

This investigation was supported by The National Fund for Scientific and Technological Development  FONDECYT/REGULAR N°1211246; FONDECYT/ INICIACIÓN N° 11230690 and Climat-AmSud CLI2020005 Chile. Student support came from the University of Maine Flagship Doctoral Research Fellowship to GF-M.