Captive Porpoises Research Articles

Behavioral laterality in Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis)

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is a critically endangered species with less than 1000 individuals expected to be left in the wild. While many studies have been conducted on laterality among several cetacean species, no studies investigating the Yangtze finless porpoise have been conducted. Using event sampling methods, several behaviors such as flipper-body touching, object touching, barrel-rolls, side swimming, and swimming direction were recorded from six captive porpoises (three males and three females). Analyses of 360 observations recorded over two months revealed that, at group level, porpoises showed laterality in swimming behaviors. Porpoises swam preferentially with their right pectoral fin upward and their left pectoral fin downward with a clockwise swimming direction and also displayed a consistent bias for a counterclockwise barrel-roll direction. No significant differences were reported for flipper use either during the interaction with conspecifics or with objects. The results from the current study provide novel insight into the cerebral asymmetry in a species previously ignored within the literature, thus improving our understanding on the extent of laterality in cetaceans and on the evolutionary history of hemispheric laterality for vertebrates in general.

Detection of Helicobacter in the fecal material of the endangered Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis

In animals, infection by the Epsilonproteobacteria Helicobacter spp. and H. cetorum is widespread. It has been suggested that H. cetorum may cause gastritis in cetaceans. The aim of our study was to investigate the presence of Helicobacter spp. in the fecal material of the endangered Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis. The fecal material of 12 porpoises living in the wild in Poyang Lake and 1 porpoise living in captivity at the Wuhan Baiji Dolphinarium were examined by PCR for the presence of Helicobacter spp. The fecal material of 8 of 12 wild porpoises and the captive porpoise were positive for Helicobacter spp. as determined by PCR using Helicobacter-specific primers, which target the 16S rRNA gene. A 16S rRNA clone library was then prepared from 1 sample isolated from a female porpoise living in the wild. DNA sequence analysis from 3 of the clones showed 98 to 99% identity to the H. cetorum 16S rRNA gene. These results demonstrate the prevalence of Helicobacter spp. and H. cetorum in endangered freshwater finless porpoises.

Low-frequency components in harbor porpoise (Phocoena phocoena) clicks: communication signal, by-products, or artifacts?

Underwater sound signals for biosonar and communication normally have different source properties to serve the purposes of generating efficient acoustic backscatter from small objects or conveying information to conspecifics. Harbor porpoises (Phocoena phocoena) are nonwhistling toothed whales that produce directional, narrowband, high-frequency (HF) echolocation clicks. This study tests the hypothesis that their 130 kHz HF clicks also contain a low-frequency (LF) component more suited for communication. Clicks from three captive porpoises were analyzed to quantify the LF and HF source properties. The LF component is 59 (S.E.M=1.45 dB) dB lower than the HF component recorded on axis, and even at extreme off-axis angles of up to 135 degrees , the HF component is 9 dB higher than the LF component. Consequently, the active space of the HF component will always be larger than that of the LF component. It is concluded that the LF component is a by-product of the sound generator rather than a dedicated pulse produced to serve communication purposes. It is demonstrated that distortion and clipping in analog tape recorders can explain some of the prominent LF components reported in earlier studies, emphasizing the risk of erroneous classification of sound types based on recording artifacts.

HEMATOLOGY VALUES OF WILD HARBOR PORPOISES (PHOCOENA PHOCOENA) FROM THE BAY OF FUNDY, CANADA

AbstractClinical hematology values were determined for 29 harbor porpoises (Phocoena phocoena) released from herring weirs in the Bay of Fundy, Canada. Erythrocyte values exhibited narrow ranges, but there was a high degree of individual variability in counts of white blood cells. Total white cell counts ranged from 2.6 to 15.5 ± 109/liter, with an overall mean of 6.5 ± 2.7 ± 10±/liter. There were significant differences among reproductive classes in mean values of total red blood cells, hematocrit (HCT), mean cell volume (MCV), mean cell hemoglobin (MCHC) and total monocyte count. Wild harbor porpoises had fewer white blood cells, lower relative total number of neutrophils and lymphocytes, and higher percentages of monocytes and eosinophils than reported in the literature for captive porpoises. Compared to published values for other odontocetes, the hemograms of harbor porpoises were most similar to those of Pacific white‐sided dolphins (Lagenorhynchus acutus). These hematology data represent a baseline from free‐ranging harbor porpoises that can be used as a reference for long‐term monitoring of the health of this population and as a tool for rehabilitation facilities.

Passive acoustic tracking of echolocating harbor porpoise (Phocoena phocoena). I. Fisheries management requirements and biological basis

Harbor porpoises are incidentally taken in various sink gillnet fisheries nationally. Little is known about the mechanism of these entanglements. To protect these animals as required by the Marine Mammal Protection Act (MMPA), fishery managers use time area closures and/or permit the use of acoustic deterrent devices (pingers) to reduce bycatch. To understand how an entanglement occurs and how the pingers function, one must understand the underwater behavior of the animals. Studies of captive porpoises, and using mounted instrumentation on released animals, have shown some aspects of porpoise life history but may or may not reveal natural behavior. A research program was initiated to determine the feasibility of passively tracking wild harbor porpoise using their echolocation signals (clicks) and observing their underwater movements in three dimensions. Additionally, details of these movements during feeding, traveling, and social events may provide an insight into their behavior that makes them prone to entanglement. Preliminary results demonstrate that the underwater tracking of harbor porpoises can be accomplished using this technique and several aspects of the animal’s natural behavior and communication are presented. A next generation autonomous system, to be deployed near actively fishing sink gillnets being developed, is described. [Work supported by NMFS and the URI/NOAA CMER Program.]

Auditory Perception of Submerged Objects by Porpoises

Two captive porpoises (or bottle-nosed dolphins) were given a variety of tests for their ability to perceive and avoid objects in water by reflected sound signals. The tests were made in a specially constructed anechoic pool in which visual perception was eliminated by the turbidity of the water. The results showed that trains of underwater sound pulses were emitted periodically by the animals in this situation whether they were swimming or at rest. The signals became more numerous when reflecting targets were lowered into the water. Sound pulses could also be triggered by surface splashes, but they were not sustained after a splash if no target was present. These porpoise sonar noises are similar in some ways to man-made sonar, although they differ from it in several important characteristics. The porpoises would locate and approach food fish by this method but would avoid nonedible objects. They were also able to swim accurately through a field of obstructions without colliding with them—even in darkness. The ability to avoid obstacles by sound did not appear to be affected by artificial jamming noises.