WINTER is an ideal time to wander around our woodlands and river banks and to find out more about trees and fish.

Most of our native trees, especially oak and ash live a lot longer than we do and anyone who manages our woodlands needs to know just how long trees live.

Last week I examined some trees which had just been cut down and I was able to count the annual rings on the stump. Trees grow at different rates in the winter than is the case in the summer.

You can see the line between summer and winter growth and this line is known as an annual ring. All you have to do is to count the rings and you know how old the tree is.

You may well ask, however, if you have to cut down a tree to find out how old it is which is clearly silly. There is a scientific alternative. Tree experts have a borer and they use this to extract a core from the tree.

After counting the rings the core is put back and a substance is pushed into the wound. This serves three functions. It kills bacteria, contains a growth hormone and seals the wound.

I spent another happy couple of days strolling along rivers talking to anglers who are mostly very good naturalists. It is possible to calculate the age of fish by counting growth rings on their scales.

Once again scientists ensure that the fish are not harmed by having scales removed. Once again a healing ointment is used to prevent bacteria entering the body.

Some of our fish, especially carp can live for a long time. As our sea fish decline and catches are limited fish farming will become vital. The more we know about our native fish, the better it will be.