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 ...

The solubility of protein components in salmon (Oncorhynchus keta) and sturgeon (Acipenser transmontanus) caviar in distilled water, 5% (w/v) NaCl, 70% (v/v) ethanol at 65C, and 0.2% (w/v) NaOH was determined. The salt soluble proteins were the predominant fraction and constituted 84.2% of the recovered protein in salmon and 86.1% in sturgeon samples. The two most prominent protein fractions (1...

The Sox9 gene of Acipenser sturio, one of the most primitive vertebrates, was analyzed. No sex-specific differences were observed. Sturgeon Sox9 consists of three exons and two introns with completely conserved exon-intron boundaries showing high levels of homology to other vertebrate Sox9 sequences, especially in the N-terminus region containing the HMG box. We found strong evidence for negati...

A newly discovered virus, Namao virus, associated with morbidity and mortality, was detected among juvenile lake sturgeon Acipenser fulvescens being propagated by a conservation stocking program for this endangered species in Manitoba, Canada. The outbreaks resulted in cumulative mortalities of 62 to 99.6% among progeny of wild Winnipeg River or Nelson River lake sturgeon and occurred at 2 geog...

Green and white sturgeon are species of high conservational and economic interest, particularly in the San Francisco Bay Delta (SFBD) for which significant climate change-derived alterations in salinity and nutritional patterns are forecasted. Although there is paucity of information, it is critical to test the network of biological responses underlying the capacity of animals to tolerate curre...

Ribosomal DNA in sturgeon is informative when analyzed at the molecular level because it bears unique characteristics that are, to a certain extent, ancestral within vertebrates. In this paper, we examine the structure and the molecular evolution of the 5S ribosomal DNA (rDNA) region in 13 sturgeon species, comparing both the 5S ribosomal RNA (rRNA) genes and the non-transcribed spacer (NTS) se...

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...

The white sturgeon, Acipenser transmontanus, is a primitive bony fish that is recognized as an important emerging species for aquaculture. However, many aspects of its stress and reproductive physiology remain unclear. These processes are controlled by various steroid hormones. In order to investigate the regulation of steroidogenesis associated with acute stress in sturgeon, a cDNA-encoding st...