Migrating Salmon Polluting Alaska Lakes - Study
Date: 18-Sep-03
Country: UK
"After spawning, the fish die in their thousands -- delivering their toxic cargo to the lake sediment and increasing its PCB content more than sevenfold," Jules Blais, of the University of Ottawa, said in a report in the science journal Nature.
Sockeye salmon spend most of their lives in the ocean where they acquire PCBs in their fat stores but return to the lakes to spawn and die. Blais and his colleagues found the raised PCB levels while studying sediment samples collected over several years from eight Alaskan lakes.
They estimate that one million adult salmon could transport more than one-third pound of the pollutants to the spawning area.
"The amount of PCBs transported by sockeye salmon to these lakes is greater than the traditional assignment from atmospheric pathways," said Blais.
The scientists fear the pollutants could harm predators such as bears or eagles. In humans PCBs can cause cancer, reproductive problems and damage to the nervous system.