A novel approach for induced out-of-season spawning of Eurasian perch, Perca fluviatilis

摘要

In this study, the systematic development of a protocol allowing an effective advanced spawning of wild Eurasian perch with the use of salmon gonadoliberin analogue (sGnRHa) was undertaken. The novel approach used in this study involved the application of a strategy of the repeated administration of sGnRHa (i.e., the hormone was given in two doses: priming and resolving) along with an additional thermal stimulation of ovulation. Additionally, the developed protocol was tested for its suitability in the controlled reproduction of domesticated broodstock. The obtained results suggested that the best interval between the hormonal treatments is 7 days when a water temperature of 10 degrees C is kept constant between the two injections and when the resolving injection is followed by rapid increments of temperature up to 12 degrees C, at which spawning is expected. This study revealed that the most suitable priming dose of sGnRHa was 10 mu g kg(-1), at which the highest embryonic survival rates ( > 80%) and spawning efficiency indexes ( > 500 larvae kg(-1)) (SEI: representing the number of larvae with an inflated swim bladder obtained from 1 kg of a spawned female) were recorded. Furthermore, in most cases, the application of the resolving injection yielded an embryonic survival rate of over 85% with the highest ovulation rate (100%) and SEI values observed in the group injected with 10 and 25 mu g kg(-1) at the priming and resolving doses, respectively. Repeated administrations of sGnRHa were more effective than a previous strategy typically applied for the induction of ovulation in Eurasian perch (a single application of sGnRHa or human chorionic gonadotropin). Moreover, the protocol applied to wild perch can be fully transferrable to domesticated broodstock, which makes it a valuable tool for the improvement of controlled reproduction of this species for intensive aquaculture purposes.