Spatial Ecology of the North Atlantic Right Whale (Eubalaena Glacialis)
Abstract
Despite decades of protection, the endangered North Atlantic right whale (Eubalaena
glacialis) has failed to recover, primarily due to interactions with fishing gear
and ship strikes. Right whales range along the U.S. east coast, foraging year round
in the Gulf of Maine while a subset of the population travels to the South Atlantic
Bight each year to calve. The habitat requirements of the right whale are poorly understood.
I investigated the relationship between the distribution of right whales and physical
oceanographic conditions in an effort to create predictive models of essential right
whale habitats. Additionally, the distribution of right and humpback whales (Megaptera
novaeangliae) relative to fixed fishing gear was examined to assess spatio-temporal
overlap. Habitat preferences were assessed using aerial survey data of whale locations
and a range of topological and satellite derived physical parameters including bathymetry,
sediment type, sea surface temperature, thermal gradients and surface roughness. A
suite of non-parametric quantitative techniques including Mantel tests, log likelihood
functions, Generalized Additive Models, Spearman Rank Correlations and the Williamson's
spatial overlap index were used to assess relationships between whales and habitat
variables. Our findings indicate that suitable calving habitat along the east coast
may extend much farther to the north than is currently recognized. Our model correctly
identified several well documented current and historic calving grounds in the eastern
Atlantic but failed to fully identify a heavily used calving area off Argentina, which
is characterized by lower surface water temperatures than the other calving regions.
In the Gulf of Maine, right whale distribution was correlated primarily with sea surface
temperature, sediment type and bathymetry. Predictive models offered insights into
right whale habitat preferences for foraging but failed to wholly capture the physical
factors underlying right whale distribution. I found the relative density of right
and humpback whales and fixed fishing gear in the Gulf of Maine to be negatively correlated
in most seasons and areas. These findings demonstrate that the regular co-occurrence
of high densities of whales and gear is not a prerequisite for entanglement. Prohibiting
entangling lines in areas where whales are known to forage could substantively reduce
entanglement.
Type
DissertationDepartment
EcologySubject
Biology, Ecologyright whale
spatial analysis
habitat modeling
calving habitat
foraging habitat
entanglement
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https://hdl.handle.net/10161/588Citation
Good, Caroline (2008). Spatial Ecology of the North Atlantic Right Whale (Eubalaena Glacialis). Dissertation, Duke University. Retrieved from https://hdl.handle.net/10161/588.Collections
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