The rivers and streams contain trout including a European variety known as the marbled trout that grow to a rather large size. Grayling is another common target of the fly fisherman. The grayling is a fish found across Europe. It is related to the salmon and grows to a maximum length of 24 inches and a maximum weight of nearly 15 pounds. Centuries of fishing pressure and industrial pollution have greatly reduced the native populations of trout and grayling, but Italy has been engaged in a very active conservation program that has been slowly restoring their native inland fisheries. Catch and release areas are very common in the fly fishing areas of Italy for this reason.