Featured Research

from universities, journals, and other organizations

Iron, steel in hatcheries may distort magnetic 'map sense' of steelhead

Date:
June 3, 2014
Source:
Oregon State University
Summary:
Exposure to iron pipes and steel rebar, such as the materials found in most hatcheries, affects the navigation ability of young steelhead trout by altering the important magnetic 'map sense' they need for migration. "The better fish navigate, the higher their survival rate," said a researcher. "When their magnetic field is altered, the fish get confused."

This graph shows the ocean range of Chinook salmon and the orientation of the fish to the magnetic force. Fish presented with a northern orientation swam south and vice versa. The experiment was later repeated with steelhead trout and results were similar.
Credit: Nathan Putman, Oregon State University

Exposure to iron pipes and steel rebar, such as the materials found in most hatcheries, affects the navigation ability of young steelhead trout by altering the important magnetic "map sense" they need for migration, according to new research from Oregon State University.

The exposure to iron and steel distorts the magnetic field around the fish, affecting their ability to navigate, said Nathan Putman, who led the study while working as a postdoctoral researcher in the Department of Fisheries and Wildlife, part of OSU's College of Agricultural Sciences.

Just last year Putman and other researchers presented evidence of a correlation between the oceanic migration patterns of salmon and drift of Earth's magnetic field. Earlier this year they confirmed the ability of salmon to navigate using the magnetic field in experiments at the Oregon Hatchery Research Center. Scientists for decades have studied how salmon find their way across vast stretches of ocean.

"The better fish navigate, the higher their survival rate," said Putman, who conducted the research at the Oregon Hatchery Research Center in the Alsea River basin last year. "When their magnetic field is altered, the fish get confused."

Subtle differences in the magnetic environment within hatcheries could help explain why some hatchery fish do better than others when they are released into the wild, Putman said. Stabilizing the magnetic field by using alternative forms of hatchery construction may be one way to produce a better yield of fish, he said.

"It's not a hopeless problem," he said. "You can fix these kinds of things. Retrofitting hatcheries with non-magnetic materials might be worth doing if it leads to making better fish."

Putman's findings were published this week in the journal Biology Letters. The research was funded by Oregon Sea Grant and the Oregon Department of Fish and Wildlife, with support from Oregon State University. Co-authors of the study are OSU's David Noakes, senior scientist at the Oregon Hatchery Research Center, and Amanda Meinke of the Oregon Hatchery Research Center.

The new findings follow earlier research by Putman and others that confirmed the connection between salmon and Earth's magnetic field. Researchers exposed hundreds of juvenile Chinook salmon to different magnetic fields that exist at the latitudinal extremes of their oceanic range.

Fish responded to these "simulated magnetic displacements" by swimming in the direction that would bring them toward the center of their marine feeding grounds. In essence, the research confirmed that fish possess a map sense, determining where they are and which way to swim based on the magnetic fields they encounter.

Putman repeated that experiment with the steelhead trout and achieved similar results. He then expanded the research to determine if changes to the magnetic field in which fish were reared would affect their map sense. One group of fish was maintained in a fiberglass tank, while the other group was raised in a similar tank but in the vicinity of iron pipes and a concrete floor with steel rebar, which produced a sharp gradient of magnetic field intensity within the tank. Iron pipes and steel reinforced concrete are common in fish hatcheries.

The scientists monitored and photographed the juvenile steelhead, called parr, and tracked the direction in which they were swimming during simulated magnetic displacement experiments. The steelhead reared in a natural magnetic field adjusted their map sense and tended to swim in the same direction. But fish that were exposed to the iron pipes and steel-reinforced concrete failed to show the appropriate orientation and swam in random directions.

More research is needed to determine exactly what that means for the fish. The loss of their map sense could be temporary and they could recalibrate their magnetic sense after a period of time, Putman said. Alternatively, if there is a critical window in which the steelhead's map sense is imprinted, and it is exposed to an altered magnetic field then, the fish could remain confused forever, he said.

"There is evidence in other animals, especially in birds, that either is possible," said Putman, who now works for the National Oceanic and Atmospheric Administration. "We don't know enough about fish yet to know which is which. We should be able to figure that out with some simple experiments."


Story Source:

The above story is based on materials provided by Oregon State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. N. F. Putman, A. M. Meinke, D. L. G. Noakes. Rearing in a distorted magnetic field disrupts the 'map sense' of juvenile steelhead trout. Biology Letters, 2014; 10 (6): 20140169 DOI: 10.1098/rsbl.2014.0169

Cite This Page:

Oregon State University. "Iron, steel in hatcheries may distort magnetic 'map sense' of steelhead." ScienceDaily. ScienceDaily, 3 June 2014. <www.sciencedaily.com/releases/2014/06/140603194009.htm>.
Oregon State University. (2014, June 3). Iron, steel in hatcheries may distort magnetic 'map sense' of steelhead. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/06/140603194009.htm
Oregon State University. "Iron, steel in hatcheries may distort magnetic 'map sense' of steelhead." ScienceDaily. www.sciencedaily.com/releases/2014/06/140603194009.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Xtreme Eating: Your Daily Caloric Intake All On One Plate

Xtreme Eating: Your Daily Caloric Intake All On One Plate

Newsy (July 30, 2014) The Center for Science in the Public Interest released its 2014 list of single meals with whopping calorie counts. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins