Robert D. Kenney

Cetaceans in the Great South Channel, 1979–1989: right whale (Eubalaena glacialis)

A continuous 11-year time-series of aerial and shipboard survey data in the Great South Channel region reveals a remarkably consistent pattern of right whale distribution, with several interesting variations. Right whales occur in the area during the spring, with a distinct peak in May. Arrival and departure dates appear to vary by a month or more between years. The distribution is concentrated in the deeper basin north of the V-shaped 100-m isobath and a thermal front which approximately parallels the isobath. Within a single year, this concentration tends to be within a relatively small area and may remain stable for days or weeks. The center of distribution changes between years, and in 1984, 1987 and 1989 was on the eastern side of the basin rather than the “typical” western side. At any one time, nearly all of the right whales may aggregate into one to several clusters of <10 km2 each. A gradual southward shift in the center of distribution can be observed as the season progresses. Single-day abundance estimates, uncorrected for animals missed while submerged, ranged up to 179 animals. There was a statistically significant long-term increase in right whale sighting rates in the region, after correcting for estimated increases in survey efficiency, of 3.8% per year. This suggests that the population might be recovering, albeit slowly, from extreme depletion. It is likely that a significant proportion of the western North Atlantic right whale population utilizes the Great South Channel region as a feeding area each spring, aggregating to exploit exceptionally dense copepod patches.

Dive patterns of tagged right whales in the Great South Channel

Abstract Right whales were tagged in 1988 and 1989 with radio and sonic telemetry tags as part of a multidisciplinary investigation of right whales and their habitat in the Great South Channel region east of Cape Cod. The tags yielded data on the durations of 6456 dives and 6482 surfacings, as well as 23,538 measurements of the depth of a diving whale. Log-survivorship analysis of the 1988 data showed a clear separation between the durations of dives between blows within a single surfacing sequence or bout (intea-bout dives) and longer dives between surfacing sequences (interbout dives) at 27 s, which was also applied to the 1989 data. Inter-bout dives averaged 127.3 s, and were significantly longer in 1988 than in 1989. Inter-bout dives were significantly longer during the day than night in 1988, and longer at night in 1989. The average intea-bout dive duration was 11.8 s, with 1989 dives longer than those in 1988. Surface durations averaged 6.2 s, and were also significantly longer in 1989. Dive depths were recorded only in 1989. Mean dive depth was 7.3 m, and only 12 dives went deeper than 30 m. The typical right whale dive pattern in 1988 included relatively short surfacings, long dives during the day, and shorter dives at night. This correlated with strong diel vertical migration by the dense zooplankton patches on which they were presumed to be feeding based on indirect evidence-from near the surface at night to near the bottom during the day. The 1989 pattern included longer dives during the night, as well as some exceptionally long surfacings. Zooplankton in 1989 did not migrate vertically, and remained near the surface day and night in right whale feeding areas. Right whale dive patterns in the Great South Channel are closely correlated with the horizontal and vertical distributions and movements of dense patches of their zooplankton prey.

Cetacean biomass densities near submarine canyons compared to adjacent shelf/slope areas

Estimated cetacean biomass densities in areas of the northeastern U.S. continental shelf edge encompassing major submarine canyons were compared to those in neighboring shelf/slope areas. It was hypothesized that biomass-densities would prove to be higher in the canyon areas: however, the analysis demonstrated significantly lower total cetacean biomass in the canyon areas. When species were analyzed individually, only spotted dolphins (Stenella spp.) showed a significant difference, with higher densities near the canyons. The canyons are apparently not more important as a cetacean habitat than the shelf break region generally.

Using hierarchical bayes to understand movement, health, and survival in the endangered north atlantic right whale.

Body condition is an indicator of health, and it plays a key role in many vital processes for mammalian species. While evidence of individual body condition can be obtained, these observations provide just brief glimpses into the health state of the animal. An analytical framework is needed for understanding how health of animals changes over space and time.Through knowledge of individual health we can better understand the status of populations. This is particularly important in endangered species, where the consequences of disruption of critical biological functions can push groups of animals rapidly toward extinction. Here we built a state-space model that provides estimates of movement, health, and survival. We assimilated 30+ years of photographic evidence of body condition and three additional visual health parameters in individual North Atlantic right whales, together with survey data, to infer the true health status as it changes over space and time. We also included the effect of reproductive status and entanglement status on health. At the population level, we estimated differential movement patterns in males and females. At the individual level, we estimated the likely animal locations each month. We estimated the relationship between observed and latent health status. Observations of body condition, skin condition, cyamid infestation on the blowholes, and rake marks all provided measures of the true underlying health. The resulting time series of individual health highlight both normal variations in health status and how anthropogenic stressors can affect the health and, ultimately, the survival of individuals. This modeling approach provides information for monitoring of health in right whales, as well as a framework for integrating observational data at the level of individuals up through the health status of the population. This framework can be broadly applied to a variety of systems – terrestrial and marine – where sporadic observations of individuals exist.

The South Channel Ocean Productivity EXperiment

Abstract The South Channel Ocean Productivity EXperiment (SCOPEX) was a multidisciplinary study of a whale-zooplankton predator-prey system in the southwestern Gulf of Maine, focusing on the oceanographic factors responsible for the development of dense patches of the copepod Calanus finmarchicus , which comprise the major prey resource for right whales ( Eubalaena glacialis ). Three non-mutually exclusive hypotheses underlay the study: patch development is due to (1) extremely high in situ primary and secondary productivity; (2) large numbers of Calanus advected into the region and concentrated by hydrographic processes; and/or (3) a behavioral tendency of the copepods themselves to aggregate. The results confirmed the cooccurrence of right whales with high density Calanus patches, and also demonstrated that right whales fed on patches with higher proportions of larger lifestages. The physical oceanographic studies supported the advection hypothesis, possibly augmented by a tendency of Calanus to aggregate, but there was little evidence to support the productivity hypothesis.

Shark distributions off the northeast United States from marine mammal surveys

Donnees sur la repartition de Cetorhinus maximus, Prionace glauca, Sphyrna zygaena et S. lewini le long des cotes atlantiques americaines

Saving endangered whales at no cost

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Recent Scientific Publications Cast Doubt on North Atlantic Right Whale Future

1 New England Aquarium, Boston, MA, USA, 2 Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA, 3 Right Whale Ecology Program, Provincetown Center for Coastal Studies, Provincetown, MA, USA, 4 Biology and Marine Biology, University of North Carolina, Wilmington, NC, USA, 5 Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA, 6 Nicholas School of the Environment and Pratt School of Engineering, Duke University

SOUNDS OF WESTERN NORTH ATLANTIC FISHES—DATA RESCUE

whether the egg mass simply falls out or is rubbed off. The egg mass is positively buoyant and composed of a transparent gelatinous mass rolled up in a scroll configuration (Fahay 1992). The egg mass gradually expands and breaks up and dissipates after 24 hours, after which time the eggs float freely until larvae begin hatching at about 36 hours. The gelatinous egg mass bears a striking superficial resemblance to a ctenophore floating in the water, suggesting a possible mimicry. However, we hypothesise that the gelatinous egg mass may instead be an adaptation to increase fertilisation success and allows daily spawning with low sperm volume.

Swim Speed, Behavior, and Movement of North Atlantic Right Whales (Eubalaena glacialis) in Coastal Waters of Northeastern Florida, USA

In a portion of the coastal waters of northeastern Florida, North Atlantic right whales (Eubalaena glacialis) occur close to shore from December through March. These waters are included within the designated critical habitat for right whales. Data on swim speed, behavior, and direction of movement – with photo-identification of individual whales – were gathered by a volunteer sighting network working alongside experienced scientists and supplemented by aerial observations. In seven years (2001–2007), 109 tracking periods or “follows” were conducted on right whales during 600 hours of observation from shore-based observers. The whales were categorized as mother-calf pairs, singles and non-mother-calf pairs, and groups of 3 or more individuals. Sample size and amount of information obtained was largest for mother-calf pairs. Swim speeds varied within and across observation periods, individuals, and categories. One category, singles and non mother-calf pairs, was significantly different from the other two – and had the largest variability and the fastest swim speeds. Median swim speed for all categories was 1.3 km/h (0.7 kn), with examples that suggest swim speeds differ between within-habitat movement and migration-mode travel. Within-habitat right whales often travel back-and-forth in a north-south, along-coast, direction, which may cause an individual to pass by a given point on several occasions, potentially increasing anthropogenic risk exposure (e.g., vessel collision, fishing gear entanglement, harassment). At times, mothers and calves engaged in lengthy stationary periods (up to 7.5 h) that included rest, nursing, and play. These mother-calf interactions have implications for communication, learning, and survival. Overall, these behaviors are relevant to population status, distribution, calving success, correlation to environmental parameters, survey efficacy, and human-impacts mitigation. These observations contribute important parameters to conservation biology, predictive modeling, and management. However, while we often search for predictions, patterns, and means, the message here is also about variability and the behavioral characteristics of individual whales.