The North Atlantic right whale (Eubalaena glacialis) is one of the most endangered marine mammal species in the world and has been intensively studied for decades. Much has been learned about its habitat, behavior, and population demographics. But until now, there was little to indicate where these whales mated, a big missing piece in the puzzle of their life history.
"A high proportion of potential mates aggregated in the central Gulf of Maine between November and January, and these same individuals produced a calf a year later. We concluded that this is a pretty strong indication of a mating ground if the gestation period is 12 months," said Tim Cole, lead author and a biologist at the Woods Hole Laboratory of NOAA’s Northeast Fisheries Science Center (NEFSC).
Through aerial surveys, the researchers documented not only how many but also which right whales were present in the study area during 2002-2008. Individual animals were identified using a photo identification catalog maintained at the New England Aquarium that includes most of the adults in the population. Using genetic data gathered in other field work, known fathers seen in the surveys were identified, as were known mothers, who were identified by association with a calf.
The resulting analyses showed that the animals seen included a higher proportion of reproductively successful animals than were present in other areas that these whales used seasonally. The researchers further assumed a 12-month gestation period for North Atlantic right whales, similar to that estimated for the closely-related southern right whale (Eubalaena australis) by the South African whale biologist Dr. Peter Best.
How definitive is the study? Cole says that while it's a strong indicator, there could well be other mating areas, and its not clear how fixed the areas might be. In fact, since the study ended, fewer right whales have been observed in the area during what would be the mating period. The study also found a similar, if less dramatic, indication that Roseway Basin - an area south of Nova Scotia - may also serve as a mating ground.
"We are still seeing right whales in the central Gulf of Maine, just not in the same numbers. They are still out there, but where they all are is the big question. The decline is significant, so something appears to have changed," Cole said. "The good news is that calf production has been fairly good, with 22 calves born in 2011, 7 in 2012, and 20 this past winter. It will be interesting to see how many calves are born next year."
Most of the North Atlantic right whale population spends the spring and summer on feeding grounds off the northeastern U.S. and the Canadian Maritimes. In late fall and early winter, pregnant females migrate to waters off the southeastern U.S. to give birth. Mothers and calves are detected during intensive aerial surveys conducted from December through March off the coasts of Florida, Georgia, South Carolina, and North Carolina. Mothers and calves return to the northeast feeding grounds in the early spring, and the calves stay with their mothers for a year following birth.
Recovery of this endangered species depends on successful reproduction, but current reproductive rates for North Atlantic right whales are much lower than those for the recovering populations of southern right whales. The reasons for this are unknown, but may include a low level of genetic variability and /or inbreeding, disease, biotoxins, pollutants, food supply limitations, and habitat loss. Increased ocean noise from coastal development could also impact the species by triggering behavioral changes that negatively impact reproduction. Determining the right whale's conception period and mating grounds are important steps in learning about the factors that may be impairing reproduction.
In addition to Cole, study authors included Allison Glass Henry, Peter Duley and Richard Pace from NOAA's Northeast Fisheries Science Center; Philip Hamilton from the New England Aquarium; Bradley White from Trent University in Ontario, Canada; and Tim Frasier from St. Mary’s University in Halifax, Nova Scotia, Canada.
NOAA Fisheries Service is dedicated to protecting and preserving our nation’s living marine resources and their habitat through scientific research, management and enforcement. NOAA Fisheries Service provides effective stewardship of these resources for the benefit of the nation, supporting coastal communities that depend upon them, and helping to provide safe and healthy seafood to consumers and recreational opportunities for the American public.
NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels.
Shelley Dawicki | EurekAlert!
Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society
Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine