Artificial propagation of the endangered Rumanian endemic warm water rudd (Scardinius racovitzai Müller 1958, Cyprinidae, Cypriniformes) for conservation needs

Scardinius racovitzai appeared to be locally adapted to an extreme high temperature environment (26–35 °C). As a species of conservation concern, due to declining ecological condition of the solitary thermal lake it could be found in (Lake Petea, Oradea, Romania) and eventual near complete abstraction of this lake, 60 adults were saved in 2014. In this study we investigated methods for induced spawning and sperm cryopreservation to aid recovery and reintroduction to restored habitats. Induced spawning was introduced successfully by intraperitoneal induction of dried carp pituitary extract and human chorion gonadotropin. Larvae and juveniles were successfully reared to age 3 months using standard methods for cyprinids. Our experiments on the cryopreservation of S. racovitzai sperm show that the extender consisting 40 mM KCl 200 mM glucose, 30 mM Tris buffered with HCL pH 8.0 is suitable for freezing warm water rudd sperm together with methanol as a cryoprotectant. By rescuing the remaining wild stock into captivity and undertaking propagation research we have prevented extinction of this rare species – more so S. racovitzai will be important in the study of freshwater fishes and how they can adapt to significant warming.