The North Atlantic right whale is a critically endangered species with an estimated population of fewer than 350
Duke University
Most
North Atlantic right whales that are severely injured in fishing gear
entanglements die within three years, a new study led by scientists at the New
England Aquarium and Duke University finds.
Owen Freeman
North
Atlantic right whales are a critically endangered species whose population has
shrunk in recent decades. Scientists estimate fewer than 350 of the iconic
whales are still alive in the wild today.
To
examine the role fishing gear entanglements have played in the species'
decline, the researchers tracked the outcomes of 1,196 entanglements involving
573 right whales between 1980 and 2011 and categorized each run-in based on the
severity of the injury incurred
The
data revealed that male and female right whales with severe injuries were eight
times more likely to die than males with minor injuries, and only 44% of males
and 33% of females with severe injuries survived longer than 36 months.
Females
that did survive had much lower birth rates and longer intervals between
calving, a worrisome trend for the long-term survival of the species.
"This species is heading quickly towards extinction because of human activities," said lead author Amy Knowlton, a senior scientist at the New England Aquarium. "This study sheds further light on the role of fishing gear entanglements in their decline. Even if a right whale survives an entanglement, the injuries it sustains endure and can impact its health."
"Our
findings underscore the urgent need for changes to the fixed gear fishing
industry," said Robert Schick, a research scientist at Duke's Nicholas
School of the Environment, who was a co-lead author of the study.
Knowlton,
Schick and their colleagues published their peer-reviewed, open-access study
June 14 in the journal Conservation Science and Policy.
Entanglements
of North Atlantic right whales typically occur in fixed fishing gear, including
lobster and crab pots and gillnets, after an animal collides with ropes in the
water. The resulting injuries can range from superficial wounds with no gear
still attached to the whale's body, to cases where the fishing line wraps
tightly around the body, possibly many times, causing deep wounds, impaired
feeding, and much higher energy expenditure for the whale as it drags the heavy
gear through the open ocean.
While
most gear interactions result only in scars, the new study shows that the rate
of serious entanglements -- those with attached gear or severe injuries -- is
increasing and the sub-lethal effects of these entanglements are more
pronounced than previously reported.
"What
really surprised us was the reduction in survival regardless of whether gear
remains attached or not, which was especially apparent in females," said
Schick.
Although
right whales have shown an ability to adapt to many threats, including how
climate change is making the prey species they depend on for food less
predictable and harder to find, the new findings suggest they are having a
tougher time adapting to changes in fishing activities, including the expansion
of fishing efforts and the strengthening of ropes. These findings amplify other
recent research that suggest human activities, especially fishing gear
entanglements, are the primary cause of death and serious injury to North
Atlantic right whales and are the primary contributor to the current population
decline.
"If
we are going to save right whales from imminent extinction, dramatic changes to
how fixed fishing gear activities are presently conducted are required,"
Knowlton said. "We believe these changes will require support from both
the U.S. and Canadian governments to help the fishing industry transition to
gear that will allow the industry to operate in a manner that is safer for
whales and other marine species," she said.
Knowlton
and Schick conducted the new study with James Clark of Duke's Nicholas School,
and Philip Hamilton, Scott Kraus, Heather Pettis, and Rosalind Rolland of the
New England Aquarium. Schick also holds a research appointment at the
University of St. Andrews in Scotland.
Funding
came from the U.S. Office of Naval Research and the U.S. Department of
Defense's Strategic Environmental Research and Development Program.
Story
Source:
Materials provided by Duke University. Note: Content may
be edited for style and length.
