STAMFORD, Conn. (AP) A study by a University of Connecticut professor has found increased levels of mercury in fish in seven waterways.

The Hearst Connecticut Media Group and Connecticut Health Investigative Team report that the study by Christopher Perkins showed that fish in waterways such as Canoe Brook Lake in Trumbull and Lake Kenosia in Danbury contained increased levels of mercury.

However, in 22 lakes tested statewide where comparisons were made from one year to the next, mercury concentration declined by 17 percent. It fell from 0.41 parts per million in 1995 to 0.34 parts per million in 2005-06, the most recent data available.

But it's still higher than the 0.2 parts per million threshold for unhealthy mercury levels.

Mercury, which is toxic to humans, can attack the central nervous system and damage the brain, heart, lungs, kidneys and immune system.