An extract from my recent book, On Fishing, was published in these pages in October. In it I tried to communicate what fishing means to me and gives to me, by describing only three hours spent on one tiny stream in pursuit of wild and wily little trout. It attracted a lot of correspondence.

For most who wrote at the time, I seemed to ring one bell or another. The exception was the reader in Richmond, Surrey, who said that the piece had confirmed all he’d thought about angling: that it was a sport that depended on luck and the weather and that those likely to get the most from it were the fully lobotomised. Unsurprisingly, perhaps, I declined this gentleman’s invitation to “get a life — and take up golf, like me”.

Then, last week, I received a letter from a reader in Hamilton, Montana, oddly sent by snail-mail and much delayed in the post. This reader said that he thought I had caught the pleasure and absorption of fishing much as he experienced it but that something was missing. Fishing was not only about being at the water and wetting a line. Angling could engage in so many ways, in season and out, and not only at the waterside but away from it. Why didn’t I mention these meanders some time? How about the collectors and the fly-tyers, for a start?

My American friend was right. Fishing has given rise to many subsidiary passions. The start of a new trout season — it gets fully under way this month — may seem an odd time to raise them, but it will keep my American reader on side.

I have mentioned angling’s astonishing literature before — and the fact that tens of thousands of anglers collect fishing books, mostly, in a minor way. Izaak Walton’s 1653 master work, The Compleat Angler, will be known to them all, but the best-known book on any sport is by no means the first book on fishing, or even in its early editions the most prized by collectors.

Angling’s literature has been in full flood since 1496, when the first text appeared. History may have got the author of the Treatyse of Fysshynge wyth an Angle wrong — it has long attributed the work to one Dame Juliana Berners, allegedly a nun, on very slender evidence — yet the book has seminal importance and several early printings exist.

Most collectors, like me, are at the tenner, go-on-then-twenty end of the market, but huge money chases rare originals such as this. In 2005 a copy of The Boke of Hawkynge and Huntynge and Fysshynge, published around 1518 and containing only the second printing of the text attributed to Berners, fetched an astonishing £110,000 — commission extra — when it was auctioned in London. More recent books have fetched £20,000, £30,000 and £40,000-plus apiece in the past few years.

Fly-tying — that is, tying by enthusiasts who create flies as works of art as opposed merely to a means of catching fish — is another distinct activity within angling. Some tyers specialise in dressings of trout and salmon flies tied to ancient and exotic designs, others in creating imitations of natural flies so much like the real thing that the two can scarcely be told apart.

The world of close imitation has produced some wonderful boasts of accuracy, my favourite being one recorded by a 19th-century angler in the records of the ancient Houghton Club in Hampshire. He claimed to have created such a realistic imitation of a female mayfly that “the moment I opened my box it was rodgered by a natural”.

There is a fly-tyers’ organisation. The Fly Dressers’ Guild has been in existence for 40 years and has branches throughout Britain, in the United States and Japan. The highlight of the fly-tying year comes each autumn with the British Fly Fair — a huge event that, last year, supported 80 stands and involved demonstrations by 60 fly-dressers from 16 countries. Old tackle, likewise, is avidly collected and, again, large numbers of anglers pursue it. Three tackle auctions were held in March alone and together they landed close on £600,000.

According to Chris Sandford, a well-known collector from West Sussex who writes about angling antiques, pretty well every angling artefact is collected by someone. Reels fetch the highest prices and early reels made by Hardy Bros, of Alnwick, are especially sought-after. Only a couple of weeks ago a Hardy Cascapedia 1/0 reel, made between 1935 and 1938, went under the hammer at £15,000 plus commission. Other reels have fetched higher prices. The next big auction will be staged by Bonhams on July 19.

Some anglers choose to devote their non-fishing time to studying certain species and protecting their habitats. The Specialist Anglers’ Alliance has within it study groups for barbel, carp, catfish, chub, eels, pike, zander, roach and tench. There are influential conservation groups for grayling, trout and salmon. The efforts of all of them are year-round, in season and out.

And there is more. So, yes, fishing is indeed about wetting a line — but not only that, as my American reader pointed out. The motto of the famous Flyfishers’ Club, in London, Piscator non solum piscatur — there is more to fishing than catching fish — hits it exactly. Over the next few weeks, young trout anglers heading for the banks and the start of their season, may take convincing. A few years on, with their fires lit and a few pounds in their pockets, they will discover that it is true.

Explore More Sport

• Athletics

• Boxing

• Cycling

• Sailing

• US Sport