Baumgartner and his colleagues studied the behavior of right whales and sei whales—both endangered species of baleen whales—in the waters of the Gulf of Maine to the east of Nantucket. They found that the location, the length of stay, and perhaps the very abundance of the whales may be dependent on an interesting vertical migration pattern by the copepods on which the whales feed. It seems to be a case, he said, of “how the behavior of the prey influences the behavior of the whales.”
The algae-eating copepod, Calanus finmarchicus, appears to migrate up and down in the water column to avoid being eaten by predators such as herring and sand lance. Since these fish need to see their prey in order to feed, copepods often remain at depths where sunlight will not penetrate during the daytime. Under cover of night, they leave this deep, dark refuge, swim to the surface, and feed on algae in relative safety.
In turn, this pattern, the scientists report in a recent issue of the journal Marine Ecology Progress Series, has a “dramatic impact” on the behavior and whereabouts of the whales. They found that right whales, which are capable of feeding at depths of 450 to 600 feet below the surface, continued to stay in the area and feed on copepods deep in the water column during the day. The sei whales, on the other hand, were “significantly less abundant” when the copepods displayed vertical migration. Unlike the right whales, the sei whales probably cannot feed at depth during the day, so they may leave the area in search of better feeding conditions elsewhere.
For reasons not well understood, the critically endangered right whale is vulnerable to being hit by ships while at the surface. Baumgartner points out that nighttime may prove particularly dangerous for right whales as they feed on copepods that have migrated to the surface, yet captains piloting ships in the dark have no way to see and avoid the whales.
“Our study also helps us understand why right whales stick around in this area, from about mid April to mid June,” Baumgartner said. Because of their ability to feed below the surface, “they are able to out-compete the herring” for food, he said.
It had been thought that the recovery of herring stocks in the last decade might further threaten the right whale by depleting its food supply, Baumgartner said. But these latest observations—along with a rise in the North Atlantic right whale population from roughly 300 to 400 since 1999—suggest that herring recovery does not threaten the right whale population, he said.
At the same time, the herring and sand lance, by inducing the copepods’ vertical migration behavior, “are likely influencing the distribution and abundance of sei whales” in that area, the researchers report. However, since the sei whale population numbers in the thousands, Baumgartner said their tendency to go elsewhere to look for food is not as great a concern as it would be for the right whale.
“The good news is that the recovery of herring stocks is not going to be a problem for the right whale population,” Baumgartner said. “The bad news is that if the right whales are feeding at the surface at night, they are at greater risk for ship strikes than we had thought earlier.”
The study was conducted during the spring seasons of 2005, 2006 and 2007.
Baumgartner was joined in the study by Nadine S.J. Lysiak of WHOI and researchers from UMass Boston and the NOAA Northeast Fisheries Science Center in Woods Hole.
Funding was provided by NOAA, the Office of Naval Research, the WHOI Ocean Life Institute, and the WHOI John E. and Anne W. Sawyer Endowed Fund.
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.
Media Relations | EurekAlert!
Value from wastewater
16.08.2017 | Hochschule Landshut
Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences