The Firth of Forth combines a rich wildlife with a history of long and intense human activity around its shores and in its waters. At one time,herring, cod and haddock, with many other edible fish, were vastly more numerous, but seals and seabirds much rarer than they are now. Once, the rivers running into the Firth were so polluted that people could set fire to some of the burns; now the water is often as pure as it has ever been since records began.