March sees the start of the three month long coarse fish spawning season.

I'm standing above the mouth of the Hogsmill River in Kingston watching two very large pike side by side preparing to spawn.

The final 100 metre stretch of the Hogsmill from Clattern Bridge to where it empties into the Thames is a haven for fish. Peer over the bridge upstream and large chub can be seen nosing into the current whilst in the Thames itself, perch, roach, dace and bream abound.

On hot summer days, enormous carp of over 30lbs weight rise to the surface to slurp in mouthfuls of bread intended for the swans and ducks.

In mid-summer, if we look along the river margins we will see huge shoals of tiny recently hatched fish fry of many species numbering billions ranged along both banks for miles.

They of course form a rich diet for cormorants, herons, occasional kingfishers and great crested grebes (see drawing of grebe with perch).

Then, from early May, common terns flying with a graceful bouncing buoyancy patrol the river alongside the towpath, heads pointing downwards before plunging down to pick off an unwary surface-feeding fish.

One of the most fascinating spawning tactics involves the little stickleback. It is the only British fresh water fish to construct a nest. The male, in breeding finery of silver and red, builds a barrel shaped nest out of pieces of water plant and entices a succession of females to lay eggs within.

Upon hatching, the numerous fry are guarded pugnaciously by the male until they are large enough to fend for themselves.