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Doing the Right Thing for the Right WhaleWHOI Right Whale Initiative accelerates research to help conserve an endangered species |
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(First in a three-part series)
Part 2: Diving into the Right Whale Gene Pool
Part 3: To Find Whales, Follow their Food
The situation is urgent: Seventy years after whaling was banned, the
North Atlantic right whale population has not recovered. Only 300 to
350 remain, and the species is headed toward extinction.
The threats remain dire: Right whales are frequently struck and killed
by ships or become fatally entangled in fishing gear, because their
migratory routes overlap with major fishing areas and heavily
trafficked shipping lanes along the east coasts of the United States
and Canada. In addition, the whales aren’t reproducing consistently or
fast enough to increase their numbers—perhaps because of disease,
pollutants, poor food supplies, or genetic problems.
In November 2003, the WHOI Ocean Life Institute convened a forum in
Woods Hole, gathering scientists from several institutions, along with
representatives from government and industry, to devise a collaborative
research plan to accelerate our understanding of right whale habits and
habitats. The Institute began a Right Whale Research and Conservation
Initiative, with the aim of supplying knowledge, tools, and strategies
for more effective conservation efforts.
Catalyzed by funding from the Penzance Foundation, the North Pond
Foundation, and the Virginia Wellington Cabot Foundation, the Ocean
Life Institute launched several research projects that blend the
expertise of scientists at WHOI and other institutions. Here are reports on some of their initial efforts.
What can whales hear?
Why don’t right whales hear large ships coming and avoid collisions?
Can underwater alarm systems be designed to warn whales of approaching
vessels? Researchers have been thwarted in their attempts to answer
these questions by a lack of fundamental knowledge of how—and how
much—whales can hear.
With funding from the Right Whale Initiative, WHOI biologists Darlene
Ketten and Susan Parks generated CT scan images of the internal anatomy
of mammal ears to provide the first estimates of the frequency range of
right whale hearing. Measuring hearing in large, rare, elusive marine
mammals would have been impossible without the WHOI CT scan facility
for oceanographic research. It has enabled Ketten and colleagues to
react quickly to scan and image the ears of whales that stranded and
died, as well as ears of other large mammals for comparison.
The researchers measured cochleas—the spiral structures found in all
mammal inner ears. By comparing whale cochleas with those of land
mammals (whose hearing ranges are known), Ketten showed that whales
have some of the widest hearing ranges of any mammal. To test whether
their right whale hearing estimates hold up in real life, Parks teamed
with WHOI biologist Peter Tyack and colleagues, who place noninvasive
suction-cup “tags” on whales to record ambient sound and whale
behavior. The combined work has allowed scientists to determine what
sounds whales respond to and to consider possible ship alarm strategies
to help avoid collisions.
What’s the breaking point of bones hit by ships?
Collisions with ships often leave right whales with broken jaws, but
scientists have lacked even the most rudimentary knowledge of whalebone
structure and properties to determine how bones stand up to impacts
from ship hulls. Regina Campbell-Malone, a WHOI/MIT Joint Program
graduate student, WHOI biologist Michael Moore, and colleagues from the
University of New Hampshire conducted biomechanical studies of whale
jawbones to obtain the first detailed data on the bones’ flexibility,
strength, and breaking points. Such studies will help establish the
threshold speeds and masses of vessels that will or will not kill
whales in collisions. They will help determine if reducing vessel
speeds in critical right whale habitats would reduce the likelihood of
fatal fractures.
To test the jaw’s biomechanical response to applied stress, the
researchers suspended jawbones from a crane and loaded 1,000 pounds of
weights onto a pallet hanging from the bone. Small sensors called
strain gauges measured the bones’ strength limitations and breaking
points. The researchers have also used CT scans of jawbones to
investigate the bones' density and structure (including their interior
structure) and to gain insights into the bones' capacities.
Is there a link between food supplies and pregnancies?
Like North Atlantic right whales, South Atlantic right whales (a
separate but related species) were also hunted to precariously low
levels. But the southern right whale population has rebounded
dramatically since whaling was banned. The photos at right offer a clue:
The southern whales often have a major roll of fat behind their
blowhole, which their northern cousins lack.
Carolyn Miller Angell, a WHOI guest student, and her advisor, WHOI biologist
Michael Moore, developed a cantilevered pole system to measure blubber
thickness in right whales swimming in the ocean. Their research
indicates that whales likely require adequate nutrition and body
condition to achieve successful pregnancies. Angell, who defended her
doctoral thesis on the results of the research in August 2005, also
showed a link between the amount of food available to whales in
different years and their ability to produce calves.
The research has spurred a new study by WHOI guest student Nadine
Lysiak to analyze isotopes in whale baleen, the fibrous food-filtering
material in their mouths. As they grow, whales incorporate into their
baleen isotopes from their prey and from the waters they swim in. The
experimental technique offers the potential to provide annual
histories, much like tree rings, of where and when the whales traveled
and what they ate. The work may also pinpoint previously unrecognized
migration patterns or feeding habitats—or changes in these caused by
shifts in ocean circulation or climate. A gift from WHOI Trustee
Hardwick Simmons and his wife, Sloan, is funding the research.
What factors are preventing population growth?
Assessing the state of the North Atlantic right whale population—and
ways to preserve it—requires the messy but essential task of
determining how and why whales are dying. WHOI biologist Michael Moore,
co-investigator William McClellan of the University of North Carolina,
Wilmington, and colleagues from many other institutions have undertaken
six necropsies in the past 18 months, determining that the whales were
mainly killed by ship collisions and fishing gear entanglements. The
animals were predominantly pregnant females, which represent serious
lost potential for future births.
Statistical models of whale population dynamics by biologist Hal
Caswell and other WHOI researchers have indicated that the deaths of
mature female right whales constitute a critical factor for survival of
the species. The study showed that if just two to three adult female
deaths could be prevented each year, the population trend would switch
from declining to growing. Caswell has continued his studies to
identify other sensitive factors that could be targeted to help devise
effective management strategies that will bolster population growth.
— Lonny Lippsett
Posted: January 17, 2006 [top] |
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