Captive breeding of two rare non-migratory galaxiids (Teleostei: Galaxiidae) for species conservation

Abstract

Devising effective techniques for breeding and rearing rare non-migratory galaxiids is urgently required for conservation purposes where few animals exist in the wild for translocation or reintroduction. The development of such protocols is particularly pertinent in light of recent intense widespread bushfires and long-term drought in southeastern Australia, which have increased the likelihood of the need for captive maintenance to protect and recover remnant species. In this study, we promoted reproductive maturation via manipulation of day length and temperature, and produced viable offspring from two small, endemic freshwater galaxiids, Galaxias fuscus (Mack 1936) and Galaxias longifundus (Raadik 2014) using in vitro propagation techniques. Propagation trials resulted in 425 oocytes being stripped from four ripe G. fuscus females, and 1527 oocytes from three ripe G. longifundus females. Of these, 342 (80.5%) G. fuscus and 968 (63.4%) G. longifundus eggs hatched into larvae. Newly hatched G. fuscus and G. longifundus larvae were transparent, and 8.4–9.7 mm (mean 9.0 mm TL) and 7.1–8.9 mm (mean 8.3 mm TL) consecutively. Absorption of the yolk sac by G. fuscus larvae (1.5–2.0 mm diameter) was complete 6–7 days after hatching, and for G. longifundus (1.0–1.4 mm diameter) 12–13 days after hatching. One-month-old G. fuscus measured ~16 mm and two-month-old larvae ~22 mm, and one-month-old G. longifundus ~11 mm. Methods and techniques employed may aid broader galaxiid conservation efforts.