Shrimp farmland changes over 25 years

These three images, taken by NASA’s Landsat satellite, show how shrimp farmland has changed a Pacific coastal landscape over 25 years.

Along the Pacific coast of Honduras and Nicaragua, in the Gulf of Fonseca, an aquaculture industry has developed. It’s viewed as an economic success story by some, while others decry unnecessary and destructive changes to coastal wetlands.

All three images above show the eastern end of the Gulf of Fonseca. The top image was acquired on January 19, 1986; the middle on January 23, 1999; and the bottom image on January 8, 2011. All three were captured during the dry season.

In these natural-color images, tidal (salt) flats are shades of beige and gray, mangroves are dark green and edged in brown, and inland agricultural lands are shades of brown and light green. Shrimp ponds are mostly rectangular in shape. When active and filled, the ponds take on green hues because of the phytoplankton (algae, diatoms, blue-green algae) growing in the water. When drained, the ponds are gray because of the salty, clay-filled bottom.

In the images, more ponds are dry in January 2011 than in January 1999. Over the past decade or so, shrimp farmers have decided that it’s more economically feasible to work one or two harvests during the rainy season than to fight nature for a harvest in the dry season. By draining ponds in the dry season, farmers can allow the elements (sunlight and wind) to break down algae and fish waste, while breaking the cycles of waterborne disease-carrying organisms.

Shrimp has become one of Honduras’s primary exports, and the nation is one of the largest shrimp producers in the Americas. At the same time, critics note that the industrial scale of farming has had impacts on biodiversity on land and on wild-catch fisheries in the Gulf of Fonseca. The Convention on Wetlands of International Importance (the Ramsar Convention) counts the area as a wetland of international importance. This balancing game has been going on for decades, and it is not clear if the region will stay in balance.

EarthSky interview: Peter Claggett sees change to Chesapeake Bay with Landsat

Bottom line: Three images, taken by NASA’s Landsat satellite, show how shrimp farming has changed a Pacific coastal landscape on the Gulf of Fonseca between 1986 and 2011.

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