Reproduction of endangered river lamprey (Lampetra fluviatilis) in controlled conditions

The research reported focuses on reproduction of the river lamprey Lampetra fluviatilis,(Linnaeus, 1758) in controlled conditions. There was specific emphasis on fish harvesting dates (autumn and spring), holding conditions and reproduction in a controlled environment. Attempts were also made to synchronize the time of ovulation among river lampreys, egg and sperm collections. Hormonal stimulation was conducted using carp pituitary homogenate (CPH) at a total dose of 4 mg/kg which allowed for shortening of the egg-laying period from 2 to 3 weeks to a few days while sustaining embryo survival rates and larvae quality. River lamprey males were found to not require hormonal treatment to yield good-quality sperm, as measured using the CASA system. River lamprey broodstocks adapted well to different manipulations in hatchery conditions when harvested in the autumn and spring. The results of the present study may be used to restore endangered natural populations of the river lamprey (egg and sperm collection, fertilization or gamete preservation) because ovulation and spermiation synchronization is very difficult to achieve without hormonal treatment in controlled conditions.