Cadmium May Be Eel-Killer

"They can spend more than 10 years in a river and they accumulate a lot of cadmium," said study author Patrice Gonzalez of the Centre National de la Recherche Scientifique.

As they begin the migration, the eels transform into their fully adult stage -- a silver form with a darkened back and a white belly. Once they reach the coast, their life is a mystery: No fully adult eels have ever been caught in the ocean, and their spawning has never been observed.

Their adult migration phase is where the cadmium does the most damage, the researchers found.

After exposing the eels to cadmium, the researchers simulated the six-month migration in a tank with a continuous current, and provided hormones to begin the egg maturation process, which the eels will otherwise not do in captivity. As the eels depleted their fat stores for energy, a big dose of stored cadmium was released also. This is the stage during which the eggs and eels died in the laboratory.

"We don't know exactly what the mechanism is," Gonzalez said. "But cadmium is probably an endocrine disruptor."

Although the researchers demonstrated the problem only in the laboratory, not in the environment, Dekker noted, "It's realistic to assume that it is a problem."

"The bottom line is, we have so many concerns with the eels," he said.

The good news is that the European Union last year implemented a recovery plan for European eels, Dekker said, with a target of returning the spawning stock to 40 percent of what it would be without humans' impact. "We hope to turn the tide in coming years."

Related Links:

Jessica Marshall's blog: EnvironMental Case

Center National de la Recherche Scientifique

The European eel

Planet Green

How Stuff Works: The Electric Eel