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.

Six harbor porpoises captured in herring weirs between September 1973 and September 1974 on the southern coast of New Brunswick were tagged and released. The three smallest animals were given visible dorsal fin tags, and the three larger specimens radiotelemetric packages attached to their dorsal fins. These animals were tracked using an ADFS-210 receiver coupled with a fixed-loop array on a 6.7-m mast antenna. Good signals were received at distances of up to 16 km using frequencies in the 26–28 MHz region. Most tracking problems resulted from interference from citizen-band operations and "skip" at certain times of the day and night. The transmitters appeared to cause little or no disruption of normal behavior in the larger animals. Intermittent contact was maintained for 2, 3, and 11 days respectively before the animals moved out of range. A total of 76 h, 29 min actual radiotracking time was recorded. Some tentative estimates of distances travelled per unit time, average swimming speeds, and apparent time spent foraging and feeding are tabulated.

Vulnerability assessments combine quantitative and qualitative evaluations of the exposure, sensitivity, and adaptive capacity of species or natural communities to current and future threats. When combined with the economic, ecological or evolutionary value of the species, vulnerability assessments quantify the relative risk to regional species and natural communities and can enable informed prioritization of conservation efforts. Vulnerability assessments are common practice in conservation biology, including the potential impacts of future climate scenarios. However, geographic variation in scenarios and vulnerabilities is rarely quantified. This gap is particularly limiting for informing ecosystem management given that conservation practices typically vary by sociopolitical boundaries rather than by ecological boundaries. To support prioritization of conservation actions across a range of spatial scales, we conducted the Gulf Coast Vulnerability Assessment (GCVA) for four natural communities and eleven focal species around the Gulf of Mexico based on current and future threats from climate change and land-use practices out to 2060. We used the Standardized Index of Vulnerability and Value (SIVVA) tool to assess both natural community and species vulnerabilities. We observed greater variation across ecologically delineated subregions within the Gulf Coast of the U.S. than across climate scenarios. This novel finding suggests that future vulnerability assessments incorporate regional variation and that conservation prioritization may vary across ecological subregions. Across subregions and climate scenarios the most prominent threats were legacy effects, primarily from habitat loss and degradation, that compromised the adaptive capacity of species and natural communities. The second most important threats were future threats from sea-level rise. Our results suggest that the substantial threats species and natural communities face from climate change and sea-level rise would be within their adaptive capacity were it not for historic habitat loss, fragmentation, and degradation.

No abstract