Spatial and temporal separation of toothed whales in the western North Atlantic

A diverse group of toothed whale species inhabits the pelagic habitats of
the western North Atlantic, competing for overlapping prey resources.
Historical data deficits have limited fundamental research into many of
these species, such as establishing baselines of distribution and
abundance, so their occurrence and habitat use patterns are not well
characterized. Periodic cycles in activity have been reported at a range
of temporal scales for odontocetes in other regions, such as seasonal
movements, foraging activity modulated by lunar cycles, and diel activity
patterns. A variety of spatial, temporal, and behavioral separation
strategies have also been observed among predator guilds in both marine
and terrestrial systems, and these may also contribute to ob served
spatiotemporal patterns in activity. Re cently, passive acoustic data has
been applied to monitor odontocete species continuously, with im proved
detection and species discrimination for some cryptic species. We used a
long-term passive acoustic data set collected at sites spanning the
western North Atlantic shelf-break region to quantify presence and
characterize seasonal, lunar, and diel activity patterns for 10 species.
Our re sults demonstrated strong regional preferences and clear patterns
of spatiotemporal separation between species with similar foraging
ecology. Latitudinal shifts in seasonal presence peaks may suggest
meridional seasonal migrations for some dolphin species. We also observed
strong diel activity patterns that were modulated by both seasonal and
lunar cycles. This study reveals complex behavioral patterns arising in
response to natural cycles playing out over multiple temporal scales and
provides new in sights into habitat partitioning among toothed whale
species.