Husbandry conditions in burbot (Lota lota L.): Impact of shelter availability and stocking density on growth and behaviour

The nocturnal and benthic burbot (Lota lota L.) could be a new fish species for freshwater aquaculture. However there are no trials studying growth of juvenile and adult fish. In this study the impact of the husbandry conditions shelter availability and stocking density on growth and behaviour was investigated. In experiment 1 juvenile burbot (119.8 g ± 19.5) were reared with different shelter availability (unsheltered, medium sheltered and high sheltered) in partly covered tanks for 12 weeks and were fed overnight (10 h). In experiment 2 adult burbot (361.8 g ± 58.2) were reared at different stocking densities (2.4, 4.9 and 9.7 kg m− 2) in completely covered tanks for 16 weeks and were fed during first two night hours. Swimming activity and feeding behaviour were studied in both experiments using a video-based infrared illuminated system which started with the last day time hour and ended with the second day time hour. Different shelter availability had no effect on burbot growth (SGR: 0.65, 0.69 and 0.70% day− 1), but it did significantly affect shelter use, swimming activity and feeding behaviour. Fish of the high sheltered group showed higher shelter use, lower swimming activity and lower feeding activity. Burbot of all treatments showed a distinct feeding activity during the first three night hours (30.2% ± 12.3 for high sheltered and 44.0% ± 9.8 for unsheltered). In experiment 2 growth (SGR: 0.40, 0.41 and 0.42% day− 1) of adult burbot was not affected by stocking density meaning culturing of burbot is possible up to a density of 18 kg m− 2 without negative effects on growth and size heterogeneity. Swimming activity in the low density group was significantly lower during dawn and the first day time hour than in the other two groups. Feeding activity was significantly higher in the medium and high density group than in the low density group. This study provides a basis for further development of burbot aquaculture.