this study was accomplished to investigate the effect of artemia urmiana nauplii enriched with pediococcus acidilactici as probiotic on growth performance and survival rate of great sturgeon, huso huso.  artemia nauplii were enriched with p. acidilactici at a final concentration of 1010 cfu ml-1 in three time dependent treatments as 3 h (t3), 6 h (t6), 9 h (t9), and one non-enriched artemia as ...

Masked tonal thresholds were measured for a beluga whale at one noise level and 32 frequencies between 40 Hz and 115 kHz. Critical ratios were estimated and compared with those previously measured for the bottlenose dolphin. Beluga whale critical ratios were found to be about 3 dB lower than those of the bottlenose dolphin. Absolute tonal thresholds were extended below previous measurements to ...

A population of approximately 650 beluga (Delphinapterus leucas) inhabits a short segment of the St. Lawrence estuary (SLE). Over 17 years (1983-1999), we have examined 129 (or 49%) of 263 SLE beluga carcasses reported stranded. The major primary causes of death were respiratory and gastrointestinal infections with metazoan parasites (22%), cancer (18%), and bacterial, viral, and protozoan infe...

To understand beluga whale (Delphinapterus leucas) estuarine use in the Nelson River estuary, southwest Hudson Bay, we recorded and examined beluga movements and habitat associations for the July through August period in 2002-2005. We compared locations of belugas fitted with satellite transmitters ("tags") (2002-2005) and aerial-surveyed (2003 and 2005) belugas for years of differing freshwate...

There has been extensive sea ice loss in the Chukchi and Beaufort seas where two beluga whale (Delphinapterus leucas) populations occur between July-November. Our goal was to develop population-specific beluga habitat selection models that quantify relative use of sea ice and bathymetric features related to oceanographic processes, which can provide context to the importance of changing sea ice...

Cetaceans are remarkable for exhibiting group-specific behavioral traditions or cultures in several behavioral domains (e.g., calls, behavioral tactics), and the question of whether they can be acquired socially, for example through imitative processes, remains open. Here we used a "Do as other does" paradigm to experimentally study the ability of a beluga to imitate familiar intransitive (body...

an 8-week feeding experiment was carried out on beluga (huso huso) juvenile to evaluate the effects of different levels of fish oil containing n-3 highly unsaturated fatty acids (n-3 hufas) on fish growth and fatty acid composition. the requirements of beluga juvenile for n-3 hufas were studied by feeding fish diets containing six different levels of n-3 hufas ranging from 1.56 to 17.25% (% of ...

A small isolated population of beluga whales (Delphinapterus leucas) that are highly contaminated by pollutants, mostly of industrial origin, resides in the St. Lawrence estuary, Québec, Canada. Overhunting in the first half of the century was the probable cause for this population to dwindle from several thousand animals to the current estimate of 500. The failure of the population to recover ...

effect of different photoperiodic regimes was evaluated on growth performance and survival rate of the beluga ( huso huso ) prelarvae and larvae. newly hatched prelarvae were stored in 5 round fiberglass 500‑l tank with different photoperiod (24l:00d, 18l:06d, 12l:12d, 06l:18 d, 00l:24d) till 50 days post hatch with three replicates. light intensity was 200 lux during the experiment. feeding wa...