By TODD McLEISH/ecoRI News contributor
Chilean devil
rays can feed at depths of up to 6,000 feet. Adults can grow to a width of some
12 feet. This photo was taken during a fall aerial survey of the Northeast
Canyons and Seamounts Marine National Monument. (New England Aquarium)
A
team of scientists from the New England Aquarium has been conducting periodic
aerial surveys of the Northeast Canyons and Seamounts Marine National Monument,
some 130 miles off Nantucket, and has documented an impressive list of marine
mammals and fish that illustrates why conservation organizations have been
advocating for its protection for years.
A
late-October survey, for instance, documented three species of rare beaked
whales, three kinds of baleen whales, four species of dolphins, several ocean sunfish — the
largest bony fish in the world — and two very unusual Chilean devil rays.
“We’re
out there documenting what’s out there to show that the area is important and
should continue to be protected,” said Ester Quintana, the chief scientist of
the aerial survey team.
“Every survey is different, and you never know what you’re going to see, so
it’s always exciting.”
The
beaked whales were particularly notable, since they are rare and difficult to
observe. Beaked whales are deep-diving species that can remain under water for
more than an hour and only surface briefly to breathe.
“If you’re not at the location where they come to the surface, then you’re not going to see them,” Quintana said. “There are probably more of them out there that we were just not seeing.”
The
survey team observed two Cuvier’s beaked whales, three Sowersby’s beaked
whales, and four True’s beaked whales, the latter of which hadn’t previously
been documented in the 4,900-square-mile monument during an aerial survey,
though a ship-based group of researchers from the National Oceanic and
Atmospheric Administration had seen several there last year.
Also
observed were large numbers of Risso’s dolphins, plus groups of bottlenose
dolphins, common dolphins, and striped dolphins, along with nine fin whales,
two sperm whales, and one humpback.
“We
didn’t see many individual whales, but that’s just the difference between an
October survey and the surveys we’ve done in the summer,” Quintana said.
Of
special note were the two Chilean devil rays observed, the first time Quintana
had ever seen the species.
➤ About the size of Connecticut, the only Atlantic Ocean marine monument includes two distinct areas, one that covers three canyons and one that covers four seamounts. (NOAA)“
Last year we saw a big manta ray, which was a surprising sighting because we were unaware that they could be sighted this far north,” she said.
“So when we saw the Chilean devil ray at the site, it was another unexpected ray. They’re not that uncommon, but in the seven surveys we’ve conducted, it was the first we saw at the monument.”
Last year we saw a big manta ray, which was a surprising sighting because we were unaware that they could be sighted this far north,” she said.
“So when we saw the Chilean devil ray at the site, it was another unexpected ray. They’re not that uncommon, but in the seven surveys we’ve conducted, it was the first we saw at the monument.”
Chilean
devil rays can swim about a mile deep, and since they don't have to come to the
surface to breathe, it’s unusual to see them.
The
survey team flies transect lines back and forth over the three underwater
canyons in the monument — Oceanographer Canyon, Gilbert Canyon, and Lydonia
Canyon — with most of the wildlife observed at Gilbert and Lydonia canyons.
As soon as team members observe wildlife to document, they depart from their transect and circle the animal to identify and photograph it. The plane is equipped with a belly camera that takes photographs every 5 seconds during the survey in case the two observers miss anything.
As soon as team members observe wildlife to document, they depart from their transect and circle the animal to identify and photograph it. The plane is equipped with a belly camera that takes photographs every 5 seconds during the survey in case the two observers miss anything.
Quintana
said the team was unable to survey the waters around the monument’s four
seamounts (underwater mountains), because those sites are farther away and
their small plane can’t carry enough fuel to reach them.
The
wide variety of marine life observed during the survey are attracted to the
monument because of its diversity of habitats.
At
a lecture last February
describing the monument, Peter Auster, senior research scientist at Mystic
Aquarium, said: “Those canyons and seamounts create varied ecotones in the deep
ocean with wide depth ranges, a range of sediment types, steep gradients,
complex topography, and currents that produce upwelling, which creates unique
feeding opportunities for animals feeding in the water column.”
The
Northeast Canyons and Seamounts
Marine National Monument was designated by President Obama in
September 2016. It’s the only marine national monument in the Atlantic Ocean.
Early in President Trump’s administration, he threatened to revoke the site’s designation, despite uncertainties as to whether he could legally do so. Those threats triggered efforts by conservation groups to document the value of the site to wildlife.
Early in President Trump’s administration, he threatened to revoke the site’s designation, despite uncertainties as to whether he could legally do so. Those threats triggered efforts by conservation groups to document the value of the site to wildlife.
The
next aerial survey by the New England Aquarium team will take place as soon as
the weather cooperates. Conditions must be calm to allow for a safe flight and
smooth seas so conditions are optimal for observing marine life.
“We’ve
never done a survey in the winter because it’s hard to plan one because of the
weather,” Quintana said. “No one has ever done a survey there in the winter, so
we don’t know what to expect once we get there.”