Observations on the ventilation cycle of the harbour porpoise Phocoena phocoena (L.) in coastal waters of the Bay of Fundy

Abstract

The ventilation cycle of the harbour porpoise was studied through analysis of 700 dive sequences recorded in the Fish Harbour region of southern New Brunswick. Two basic ventilation patterns were recognized; one (pattern A) was exhibited by travelling animals and was characterized by short submergence periods (24.4 ± 1.6 s (SE)), the second (pattern B) by animals apparently feeding, and was characterized by restricted ventilation periods, between which the submergence periods averaged 1.44 ± 0.07 min. Submergences during pattern B behaviour ranged from 35 s to 4 min 4 s. One animal observed over an extended period took considerably more breaths (6.6 ± 0.4) after dives of above-average duration than after dives of less than average duration (3.6 ± 0.2). We found that the number of breaths per minute in each behaviour pattern were very similar (2.4 and 2.3, respectively), supporting statements by other workers that the energetic demands of diving in marine mammals may not be greater than that required for surface activity. In behaviour patterns A and B, respectively, harbour porpoises in this area were at the surface for only 7.2 and 7.5% of any observation period. The maximum to mean dive-time ratio in P. phocoena was noted as being almost identical to that observed in Orcinus orca; this may be a generalized relationship in all odontocetes.

Status, ecology and life history of harbour porpoise (<i>Phocoena phocoena</i>), in Danish waters

“…No marked migration pattern has been found, concurring with earlier findings of Andersen (MS 1972) for Danish waters in general and Kinze (1985b) for the Kattegat. During the summer, harbour porpoises have been found to be rather sedentary (Kinze MS 1986, 1989Watson 1976). The largest average school sizes are found in March, April and November, probably reflecting migrating animals.…”

Respiratory pattern of captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

“…breathing at a relatively stable rate during the respiration bout, and taking more breathes after a longer dive, and vice versa. Watson and Gaskin (1983) defined two different respiratory patterns for wild harbor porpoises. For "Pattern A", animals made relatively short dives and surfaced regularly, while no clear surfacing or respiration bout could be recognized.…”

“…Understanding the respiratory pattern therefore may increase understanding of the "invisible" underwater behavior. Besides, accurate measures of respiratory intervals (RIs) and quantitative analysis on the breathing pattern can provide valuable information for estimating cetacean abundance by visual "cue-counting" techniques (Hiby and Hammond 1989;Stern 1992;Kopelman and Sadove 1995;Beasley and Jefferson 2002) and for understanding the animals' physiological adaptation to the aquatic environment (Sumich 1983;Watson and Gaskin 1983;Chu 1988;Kooyman 1989).…”

“…Therefore, in most respiratory pattern analyses, the ventilation-dive cycles are firstly divided into surfacing periods, which are composed of consecutive intra-bout RIs, and diving periods, which correspond to the inter-bout RIs with relatively longer durations than the intra-bout ones, and then analyzed respectively to obtain estimates of parameters, such as the average length of inter-and intra-bout RIs, and the average number of respirations per bout (e.g. Watson and Gaskin 1983;Chu 1988;Kopelman and Sadove 1995). However, the result of the analysis depends strongly on the manner by which the bout criterion (the time criterion for respiratory bout definition) is decided.…”

“…However, in the majority of cetacean studies, researchers arbitrarily define the respiratory bout criteria as a value ranging from 15 s to 3 min (Watson and Gaskin 1983;Würsig et al 1984;Dolphin 1987a;Chu 1988;Silber et al 1988;Dorsey et al 1989;Watkins et al 2002). Although behavioral characteristics like the depth of dives or an indication of initiation of deep foraging dives were considered in addition to the arbitrary criteria in some studies (Würsig et al 1984;Dolphin 1987a;Dorsey et al 1989), which reduced the level of subjectivity in the definition, the method is highly individual and experience-dependant.…”