Yangtze Finless Porpoise Neophocaena Asiaeorientalis Research Articles

Pregnancy diagnosis and fetal monitoring in Yangtze finless porpoises

The Yangtze finless porpoise Neophocaena asiaeorientalis asiaeorientalis is a Critically Endangered species endemic to the Yangtze River and connecting lakes. Understanding the reproductive biology, fetal development, and physiology of this species is essential to ensure the successful development of a captive-breeding program. We studied pregnancy and fetal development in this species using endocrine monitoring and ultrasonographic imaging. Plasma progesterone concentrations increased significantly from non-pregnant (0.61 ± 0.43 ng ml-1) to pregnant (37.44 ± 16.18 ng ml-1) phases. Based on progesterone variation, we estimate gestation length to be approximately 12 mo. Fetal growth patterns are well described by linear regressions of thorax diameter, thorax circumference, and total body length plotted against days from parturition. Fetal growth models may be used to estimate fetal age and predict parturition date with more data in the future. Our findings provide fundamental information on pregnancy dynamics and fetal development in this Critically Endangered species to improve existing and benefit the establishment of new captive-breeding programs for Yangtze finless porpoises.

Auditory adaptation time course in the Yangtze finless porpoises, Neophocaena asiaeorientalis asiaeorientalis

ABSTRACT Auditory adaptation manifests as temporary change in the hearing sensitivity under influence of sound stimuli, and little attention has been paid to hearing adaptation in cetaceans. In a Yangtze finless porpoise Neophocaena asiaeorientalis (Cetacea, Phocoenidae), effects of long-lasting sound stimuli (pip trains) on auditory evoked potentials (AEP) were investigated. The stimuli were rhythmic tone pips of either 90 or 128 kHz frequency. Stimulus levels varied from 80 to 120 dB re 1 μPa. During stimulation, the stimulus level was either kept constant the stimulus level changed up and down by 20 or 40 dB every 1000 ms. A stimulus level increase produced quick response amplitude increase with subsequent slower exponential decay; the exponent time constant was 59.2 ± 9.7 ms. A stimulus level decrease produced quick response amplitude suppression with subsequent exponent recovery; the exponent time constant was 153.9 ± 15.9 ms. The response variations were assessed as manifestations of adaptation processes. The finless porpoise is capable of quickly adjusting its sensitivity to the current auditory scene. This flexibility allows for quick sensitivity recovery after exposure to loud noises and is important for the effective use of auditory orientation. Abbreviations: RFR: rate-following response; AEP: auditory evoked potentials; A/D: analogue-to-digital (A/D); ERD: equivalent rectangular duration

Isolation and identification of pathogenic Aeromonas veronii from a dead Yangtze finless porpoise.

Diseases caused by Aeromonas veronii in freshwater fish have been widely reported, but other species such as aquatic mammals have probably been overlooked. Here, we identified one isolate of A. veronii from a Yangtze finless porpoise Neophocaena asiaeorientalis asiaeorientalis exhibiting disease and mortality, and subsequently confirmed its virulence in artificial infection of BALB/c mice. The bacterial isolate was identified as A. veronii based on physiological, biochemical, and phenotypic features, and homology of the 16S rRNA, cpn60, rpoB, dnaJ and gyrB genes. Our results expand the known host spectrum of A. veronii, which is of great importance for the etiology of porpoise, dolphin, and other cetacean diseases.