EarthLabs > Fisheries > Lab 6: And On His Farm He Had Some Fish > 6C: Change of Scenery

And On His Farm He Had Some Fish

Part C: Change of Scenery

Satellite image of shrimp farms along the coast of Honduras. Photo courtesy of NASA Earth Observatory .

The number of coastal aquaculture facilities has increased dramatically over the last 25 years. These facilities are producing millions of tons of seafood, helping to alleviate the effects of dwindling fish populations in the oceans. However, the construction and maintenance of these facilities is not without drawbacks. Natural habitats are being altered or destroyed and pristine coastlines are becoming overdeveloped and polluted.

  1. Go to Earth Observatory's before-and-after images of shrimp farm development in Honduras .
  2. Read through the story to learn about the events responsible for the differences in the two images.

    Checking In

    Answer the following questions to check your understanding of the information contained in the article about the impacts of shrimp farming in Honduras.

    • What features in the images are represented by deep blue colors? pale pink? shades of green?
      deep blue = water features
      pale pink = non-vegetated land
      shades of green = vegetation (deep green = swampland; bright green = forested hillsides)
    • What do shrimp farms look like in the images?
      Shrimp farms appear as rows of rectangles.
    • What are the environmental impacts of mangrove destruction?
      Mangrove destruction degrades water quality, reduces habitat for fish (pitting shrimp farmers against those whose livelihood depends on fishing), increases the risk of inland flooding, and displaces coastal communities.
    • How do aquaculture ponds compromise water quality?
      The ponds themselves can contaminate the surrounding environment with too many nutrients (from fish meal fed to the shrimp), waste, and antibiotic residues. Also, the industry relies heavily on wild-caught shrimp, either larvae that have reached a given level of maturity or else pregnant females, which are transferred to the protected ponds. When done on industrial scale, the harvesting of wild shrimp in the Gulf can harm other fisheries because the nets pull up fish or other aquatic creatures that die and are discarded.

  3. Download the single image file that shows both images. Save it in an obvious place such as your Desktop or Downloads folder.
  4. Launch ImageJ and open the image file you just saved.
  5. From ImageJ's toolbar, choose the rectangular selection tool. Place your cursor on the image and drag a selection box over the top picture. Use the arrow keys to move the selection into the upper left corner of the image. Use the handles to adjust the selection size to include the date below the image.
  6. From ImageJ's menu bar, choose Image –> Duplicate... and accept the default name.
  7. Click the large image again to activate it. Click inside the yellow selection rectangle and drag it up over the top image. It is essential that the selection rectangle remains the same size.
  8. Choose Image –> Duplicate... and accept the default name again.
  9. Once you have the two images in separate windows that are the exact same size, activate the large image again and close it.
  10. From ImageJ's menu bar, choose Image –> Stacks–> Convert Images to Stack. Use the slider bar to shuffle back and forth between the before and after images.

    Checking In

    Check your understanding of the information contained in the comparison images of Honduras's Pacific coast.

    • Describe how the Pacific coast of Honduras changed between 1987 and 1999.
    • Estimate the area of land occupied by shrimp ponds in the 1999 image.

  11. Watch this ABC News Special about a new type of aquaculture facility that can help alleviate some of the adverse environmental effects associated with coastal aquaculture. NOTE: The movie clip may be preceded by a 30 second advertisement.

    Checking In

    Check your understanding of the information presented in the video clip about undersea aquaculture facilities.

    • Why do undersea aquaculture facilities have fewer negative ecosystem impacts than coastal fish farms?

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