Tuesday, November 3, 2015

Invasive North American Rainbow Trout



Lake Titicaca is South America's largest lake by volume, holding 198 cubic miles of freshwater — more water than Lake Erie, but just a fraction of Lake Michigan.

The lake rests on the border of Peru and Bolivia in the Andes Mountains, and although the region is considered the tropics, Titicaca's cold water sends a chill through the body upon touch.

The islands in Lake Titicaca may be mistaken for natural ones, but rather are woven of totora reeds. The rafts are littered with houses for the Aymara who live on the water and rely upon the lake's fish to survive. But all of the karachi in the lake are considered threatened.
 

Explorers considered the lake unproductive since all of the fish species were small.  In 1935 Peruvian and Bolivian officials met and decided that they should consider introducing supplemental fish to the lake they share. They felt the karachi were not a sufficient food source to sustain the local population.

The United States was summoned to conduct a study of Titicaca, and M.C. James, the assistant chief of fish culture for the U.S. Bureau of Fisheries, was assigned the task.

The first round of transplants — lake trout fingerlings — arrived at the lake from North America in 1938. Compared with the tiny karachi, trout were a substantial source of protein swimming through the lake's waters.

In Lake Titicaca, the trout explosion transformed local fishing practices. Rainbow trout have been the most successful of all North American trout introduced to Lake Titicaca. They are now caught by hook, farmed, sold in local markets and served in restaurants.  However, many are worried that that the traditional fishing culture will disappear as the trout decimate the karachi numbers.
  

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