Anglers' long held belief that fish-eating birds and mammals can spread diseases such as the virulent dreaded Koi Herpes Virus (KHV) in carp has been confirmed by the centre of the Environment, Fisheries and Aqua Culture Science (Cefas).

Unscrupulous fishery bosses purchasing black market carp without a health certificate have also been targeted as another source of piscatorial plagues.

Undoubtedly, highlighting the truths of man's indiscretion at the waterside is more than justified, but Cefas claims it has proof that other more natural forces are at work – fish predators.

Flocks of cormorants raid fresh water fisheries and it is suggested that they and the comparatively rare heron can spread fish disease in their droppings.

However, a complete list of mammals and birds with a possible capacity to carry fish infections across counties are mink, rats, scavenging foxes and otters.

Fish-eating birds also include the bittern, the great-crested grebe, various species of gull, the gooseander, the little tern, the kingfisher and carrion-eating members of the corvid family that forage the waterside.

While foxes, mink and rats are unprotected in law and licences may be obtained to cull cormorants and some corvids, the killing or even disturbing the habitat of most of the others mentioned is strictly prohibited by acts of parliament and European law.

Fish disease, especially KHV, has captured headlines in the last 20 years or so since the emergence of commercial carp waters.

However, while tame carp seem especially vulnerable at present, other fish species that have been susceptible to various infections that have seriously depleted their numbers in the Norfolk Broads and elsewhere, have recovered.

Remember roach disease?

Complete shoals of them disappeared during the 1970s and the spectacle of specimens between 2 and 3lb floating belly up under the bridges of the upper River Bure was not pretty.

Perch disease also decimated the huge stripeys of the Broads that produced a national record of 4lb 12oz from Oulton Broad for the late Sid Baker of Norwich in 1962.

Hardly any species have escaped trouble in our county with the worst catastrophe the Prymnesium outbreak in the Thurne waters in 1969 that wiped out millions of fish, followed by serious fish mortalities from salt water incursions ever since.

But Mother Nature has the habit of restoring the balances.

And, right now, the Norfolk Broads are well blessed with a rich population of all fish species; bigger, better and healthier than we've ever had before.

Predator anglers complain we have a pike famine but, with such an abundance of natural food, the quarry may be less interested in a bait bristling with metal spikes than feeding off a bumper crop of the real thing.

And now the endemic carp disease? Just think of rabbits losing nearly 99pc of their numbers of wild stock to Myxomatosis in the 1950s.

They are back in their thousands throughout the country.

On that evidence, perhaps the real solution is to allow nature to take its course.