Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Too Few Salmon Is Far Worse Than Too Many Boats for Killer Whales

11.06.2012
Not having enough Chinook salmon to eat stresses out southern resident killer whales in the Pacific Northwest more than having boatloads of whale watchers nearby, according to hormone levels of whales summering in the Salish Sea.

In lean times, however, the stress level normally associated with boats becomes more pronounced, further underscoring the importance of having enough prey, according to Katherine Ayres, an environmental and pet-behavior consultant who led the research while a University of Washington doctoral student in biology. Ayres is lead author of a paper appearing online June 6, in the journal PLoS ONE.

In a surprise finding, hormone levels show that southern resident killer whales are best fed when they come into the Salish Sea in the late spring, Ayres said. The Salish Sea includes Puget Sound and the straits of Georgia, Haro and Juan de Fuca. Once there they get a necessary boost later in the summer while eating Chinook salmon at the height of the Fraser River run.

While Fraser River Chinook are an important food source, helping the southern resident killer whales may mean giving additional consideration to spring runs of Chinook salmon off the mouth of the Columbia River and other salmon runs off the West Coast, if that's where the orcas are bulking up in the spring, Ayres said. "Resident" killer whales are fish-eating orcas, unlike the so-called "transient" orcas that eat marine mammals.

For the study, scientists analyzed hormonal responses to stress that were measurable in whale scat, or poop. Many samples were collected using a black Labrador named Tucker on board a small boat in the vicinity of individuals or groups of whales. Even a mile away, Tucker can pick up on the scent he's been trained to recognize as the fishy smell distinctive to southern resident killer whales, a group of orcas listed as endangered by both Canada and U.S.

"This is the first study using scat-detection dogs to locate killer whale feces," Ayres said. "The technique could be used to collect scat and study stress in other species of whales, always difficult subjects to study because the animals spend 90 percent of their time underwater."

Since the population of southern resident killer whales declined nearly 20 percent between 1995 and 2001, scientists and managers have wondered if the animals weren't thriving because of lack of food, the closeness of boats, toxins built up in their bodies or a combination of all three.

"Behavior is hard to interpret, physiology is easier," said co-author Samuel Wasser, UW professor of biology and developer of the program using dogs like Tucker to detect scat for biological research. "Fish matter most to the southern resident killer whales. Even if boats are important to consider, the way you minimize that impact is to keep the fish levels high."

It's the same with toxins, Wasser said. The study being published in PLoS ONE specifically considered stress caused by inadequate prey and boats. But Wasser said that toxins accumulating in body fat will likely affect killer whales most when food is scarce and they start to use that stored fat, releasing toxins into their bodies when their physical condition already is in decline. When whales are well-fed, toxins should be less of a factor, he said.

In the study researchers examined the level of two hormones to study physiological responses to boat and food stresses.

One type of hormone, glucocorticoids, are released in increasing amounts when animals face immediate challenges, whether it's a shortage of food or the fight-or-flight response when threatened, Ayres said. When whale watching boats and other vessels were most numerous in the summer, glucocorticoids should have spiked if the whales were bothered. Instead glucocorticoids went down, driven by an increase in the number of Fraser River Chinook.

The other hormone, thyroid hormone, tunes metabolism depending on how much food is available, for example ramping down metabolism to lower the energy an organism expends when food is scarce, Ayres said. Unlike glucocorticoids, thyroid hormone levels do not respond directly to stresses such as boats being nearby. During summers, thyroid levels of Salish Sea whales dipped while they awaited the arrival of Fraser River Chinook, increased again when food became plentiful and declined once again as the Chinook run petered out.

Unexpectedly, the thyroid hormone measures showed the whales were best fed when they first arrive in the Salish Sea, better than at any time in the five months they spent there, Wasser said.

"We assume winter is a lean time, so to come into the Salish Sea at their nutritional high for the year, then clearly they have been eating something – a very rich food source – before they arrive," Wasser said. "It appears another fish run is critical to them before they get here."

Some evidence points to the Chinook returning to the Columbia River, although Wasser said that more spring data are needed.

The PLoS ONE paper follows a draft report issued May 3 by U.S. and Canadian fisheries experts considering to what extent salmon fishing is affecting the recovery of the southern resident killer whales. Wasser said the report pays too little attention to year-to-year salmon variability, but got it right when it said more needs to be known about what's happening to the whales in the winter and, particularly, in early spring.

Among other things, the report said Chinook stocks are currently harvested at a rate of about 20 percent "so there is limited potential for increasing Chinook abundance by reducing fishing pressure," according to the executive summary.

More extreme measures may be required that increase overall Chinook salmon stocks, Wasser said.

"To support a healthy population of southern residents we may need more salmon than simply the number of fish being caught by commercial and sport fishers," Ayres said. "We may need to open up historical habitats to boost wild salmon, such as what is being done with the Elwha River and what is proposed for the Klamath River. That may be the only way to support the historic population size of southern residents, which is ultimately the goal of recovery."

Other co-authors are Rebecca Booth of the UW; Jennifer Hempelmann, Candice Emmons, M. Bradley Hanson and Michael Ford of the National Oceanic and Atmospheric Administration's Northwest Fisheries Science Center; Kari Koski of Soundwatch Boater Education Program and the Whale Museum, Friday Harbor; Robin Baird of Cascadia Research Collective, Olympia; and Kelley Balcomb-Bartok, who helped get the study off the ground through collaboration with the Center for Whale Research.

The work was funded by Washington Sea Grant based at the UW, NOAA's Northwest Fisheries Science Center, Northwest Scientific Association, UW Department of Biology and the Canadian Consulate General.
###
For more information:
Ayres, 206-817-7112, kla5@uw.edu, kayres@companionanimalsolutions.com
Wasser, 206-543-1669, wassers@uw.edu
Suggested websites
PLoS ONE paper
"Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population"

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0036842

Center for Conservation Biology, University of Washington
http://conservationbiology.net/
Conservation Canines, Center for Conservation Biology, University of Washington
http://conservationbiology.net/conservation-canines/
April 2012 video: https://www.youtube.com/watch?v=mSI7_cgxJjY
Katherine Ayres
http://companionanimalsolutions.com/blogs/whales-dogs-poop-and-conservation-biology/
Samuel Wasser
http://conservationbiology.net/about-us/staff-and-student/#sam
Draft report: "Effects of Salmon Fisheries on Southern Resident Killer Whales"
http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/ESA-Status/KW-Chnk.cfm
Department of Biology, University of Washington
http://www.biology.washington.edu/

Sandra Hines | Newswise Science News
Further information:
http://www.uw.edu

More articles from Studies and Analyses:

nachricht Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>