9781888569988-ch10

Burbot: Ecology, Management, and Culture

Aspects of Reproduction and Larviculture of Burbot Under Hatchery Conditions

Inne Vught, Alireza Shiri Harzevilli, Johan Auwerx, and Daniel De Charleroy

doi: https://doi.org/10.47886/9781888569988.ch10

Abstract.—The freshwater gadoid, burbot Lota lota, was the subject of a captive breeding program to produce larvae for reintroduction into natural waters of Flanders, Belgium. Burbot broodfish were collected in 2002 from a river in France and maintained in earthen ponds at the Fish Research Center of the Research Institute for Nature and Forest in Linkebeek, Belgium. Each winter, they underwent gonadal maturation. In October, the mature fish were transferred to stocking ponds and fed with live fish. From the middle of December, they were exposed in indoor tanks to a continuous coldwater temperature of 4°C and a simulated natural light regime. This way, natural spawning could be induced without hormonal treatment. Between 582,766 and 984,963 eggs/kg bodyweight were collected from individual fish. Eggs averaged 1.00 mm in diameter. After fertilization, hatching started around day 32–33 when incubated at about 4°C (i.e., between 128 and 132 degree-days). Seventeen days later, at about 4°C, the larvae filled their swim bladder. A few days later (on day 21–24 posthatching when kept on 4°C), the larvae started exogenous feeding. The freshwater rotifer Brachionus calyciflorus proved to be an adequate starter food for growing burbot larvae but had to be replaced by larger food organisms like Artemia after 7–8 d. Burbot larvae were grown to one-summer-old juveniles (average survival 4%, average length 10 cm) in rearing ponds. The survival rate of the juvenile burbot in the ponds after 9 months was higher when the larvae were prefed with rotifers and Artemia prior to stocking in the ponds (survival up to 28% when fed for 18 d prior to the stocking).