First feeding of burbot, Lota lota (Gadidae, Teleostei) larvae under different temperature and light conditions

Abstract

The burbot (Lota lota) is the only fresh water member of the cod family, Gadidae, and is adapted to cold waters. The effects of temperature and light on the growth and survival of burbot larvae were investigated under hatchery conditions. Three temperature regimes (12, 16 and 20°C) were applied under continuous light and darkness during the experiment. Rotifer, Brachionus calyciflorus (L.) were fed to the larvae in the first 10 days and the diet was then replaced with Artemia nauplii. At the end of the feeding stage with rotifer, growth in terms of the total length and wet weight were larger at higher temperatures under continuous light. At day 10, survival rates of the fish held at 12°C under continuous light and darkness regime were higher than those held at 16°C and 20°C kept under the same conditions. From day 10 onwards, larval growth improved remarkably after changing the live food from rotifer to Artemia in all treatments. At the end of the study, the highest survival rate was recorded among the larvae held at 12°C exposed to continuous light. Under light condition, the temperature of 20°C did not result in an improved larval growth compared with 16°C. This may indicate that high temperature and continuous light are not beneficial for larval growth and survival when they reach older stage of development. The results indicate a significant interaction for the combination of temperature, light and time with respect to survival and wet weight, making unambiguous interpretation of the main effects difficult.

A novel experiment of rearing burbot larvae in cages

“…Growth of burbot larvae reared in cages at lower densities, feeding at an ambient zooplankton density, grew better than larvae fed under intensive conditions in controlled experiments (Harzevilli et al., 2003; Harzevilli et al., 2004; Jensen et al., 2008b; Vught et al., 2008). However, an unbiased assessment of differences in growth between this study and others was not possible because of differences in experimental design and objectives.…”

“…(2003) found differences in growth of burbot larvae from about 5 to 9 mm TL in 35 days. Harzevilli et al. (2004) used different light and temperature conditions and found that the most rapid growth after 20 days occurred in 16°C water, with burbot growing from about 4 to 8 mm TL.…”

Interactions between temperature and size on the growth, size heterogeneity, mortality and cannibalism in cultured larvae and juveniles of the Asian catfish, Pangasianodon hypophthalmus (Sauvage)

“…The correspondence between T ° opt and the temperature that produces the highest survival (hereafter T ° Smax ) is not systematic in cultured fish. In P. brachypomus , there was a good correspondence between the two temperatures (Baras & Florès 2006), whereas in several other species, survival was the highest at temperatures a few degrees below T ° opt ( C. gariepinus : Verreth & Den Bieman 1987; pike silverside Menidia estor Jordan: Martínez‐Palacios, Barriga Tovar, Taylor, Ríos Durán & Ross 2002; A. minor : Hansen & Falk‐Petersen 2002; burbot Lota lota (L.): Harzevili, Douremont, Vught, Auwerx, Quataert & De Charleroy 2004). In P. hypophthalmus , the correspondence between T ° opt and T ° Smax can be explained by the relationship between size heterogeneity and the departure from T ° opt , at least during the first experiment (with fish older than 6 dah), where cannibalism was the main cause of mortality at almost all temperatures.…”

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“…In burbot larviculture, one of the biggest problem is a very high mortality rate observed in the first stages of post-embryonic development (Żarski et al, 2010). However in the present study, the survival rate of the burbot during experiments E1-E3 did not fall below 80%, like in other tests (Harzevili et al, 2004;Wocher et al, 2012). In both described experiments concerning the administration of supplemented A. salina nauplii to burbot larvae, there was no negative effect of any of the analyzed fluorochrome dyes on the final survival of the stocks.…”