Published: Aug 16, 2011 6:36 PM EDT

It's been more than a year since the gulf oil spill and some fishermen believe the gulf still hasn't completely recovered.

They say they've been catching fish with sores, fin rot and infections at a greater frequency than ever before. One researcher who studied the diseased fish is alarmed at what he found but says he can't be sure the oil spill is to blame.    

Despite not being certain the oil spill is to be blame, researchers say the highest rate of diseased fish have been found in the areas of the gulf that were most affected by the oil spill.

More tests and studies are being done to try and determine the exact cause.