Every summer and fall, endangered North Atlantic
right whales congregate in the Bay of Fundy between Nova Scotia and New
Brunswick to gorge on zooplankton. Researchers have documented the annual feast
since 1980, and well over 100 whales typically attend, a significant portion of
the entire species. Only this year, they didn’t. Just a dozen right whales
trickled in—a record low in the New England Aquarium’s 34-year-old monitoring
program. And that comes on the heels of two other low-turnout years, 2010 and
2012.
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Numbers of the critically endangered marine
mammal have been ticking up in recent years just past 500 individuals, so no
one thinks the low turnout in the Bay of Fundy augurs a decline in the species
as a whole. The right whales must have gone elsewhere. But where? And more
importantly, why?
“Our whales have been missing in their
normal habitat areas, where we’ve learned to expect them over three and a half
decades,” says Moira Brown,
a senior scientist at the aquarium who runs the monitoring program. “It’s
quite shocking when you go out there day after day after day and you don’t see
any right whales.”
This change in North Atlantic right whale
behavior is occurring against a backdrop of major climate-related ecosystem
shifts taking place throughout the northwest Atlantic Ocean. While Brown and
other right whale researchers are not ready to attribute changes in the
species’ feeding or migratory patterns to any one factor, including global
warming, what is clear to them is that the right whales’ new itinerary must
signal a shifting food supply. A zooplankton species called Calanus
finmarchicus is the whales’ mainstay. Researchers reported an unusual
scarcity of the zooplankton in the Bay of Fundy this summer. By the same token,
in Cape Cod Bay, where right whales have been unusually plentiful, other
scientists have been documenting increasing concentrations — so much so that
the normally invisible creatures noticeably color the water.
Other ecosystem shifts are afoot in the northwest
Atlantic off the eastern coasts of the United States and Canada. Sea surface
temperatures in waters such as the Gulf of Maine are rising and various marine
species, including cod and red hake, are shifting their ranges northward,
according to recent studies.
Increasing precipitation, the rapid disappearance of Arctic sea ice, and the
melting of ice sheets in Greenland and Canada are all expected to pour more
freshwater into the northwest Atlantic, causing increased stratification of
ocean waters and changes in the abundance and distribution of phytoplankton and
zooplankton at the bottom of the food chain, studies show.
Read more at Yale
Environment 360.
Whale
image via Shutterstock.