A few days ago my colleagues on home news devoted an entire page to Zyg Gregorek, from Holsworthy, Devon. Gregorek had become the first man in the world to catch all eight species of tuna on rod and line. It had taken him close on ten years to achieve the feat and he had travelled about 100,000 miles in the process.

Other newspapers reported his catch, as well. Some were as much interested in why Gregorek should want to pursue such a goal as in the fact that he had achieved it. A couple of reports characterised him as an obsessive. Inside the sport, though, scarcely an eyebrow lifted.

Angling is so vast and diverse an activity, pursued by so many millions, that it is commonplace for anglers to develop personal passions and to set themselves seemingly curious targets. Some, such as Gregorek, want to catch examples of a range of specific species; some want to catch an example of a particularly rare or difficult species; lots want to catch the most of something and especially the biggest of something. Vast numbers want to catch particular kinds of fish in particular ways.

The most obvious example of the last is fly-fishing. There are more than half a million trout fly-fishermen in Britain. Their interest is not in catching trout, but in catching trout on artificial flies. They know that they could catch more trout and often bigger trout by using real flies and real baits, but prefer not to. They accept the self-imposed handicap because fishing with imitation flies is so absorbing and aesthetic. It offers such interest and challenge. Anglers fly-fish for the pleasure it provides.

Even within fly-fishing, there are some pretty odd special interests. One of my own has been the effects of refraction on trout behaviour.

It led my friend, John Goddard, and me, when researching our book, The Trout and the Fly, to spend many absorbing hours photographing flies’ feet from under water, at night. Yes, I will repeat that: we spent many hours photographing flies’ feet, from under water, at night. A mind-jarring concept? Very likely. A definition of insanity? I’d like to think not.

We were simply trying to answer a question that had long fascinated me. It was: how could trout, in the dark, unerringly see and rise to natural flies drifting on the surface above them when we, looking down, could see nothing at all? To find the answer, we realised we had to put ourselves where the fish were, below the surface. We constructed large tanks with specially-angled sides, filled them with water, dropped flies on to the water as darkness enfolded and then crouched beneath them, looking up.

We had our answer at once. It was that wherever part of a fly — feet, body, wings — touched the surface tension, they dented it slightly. This distortion, when viewed from below, acted rather like a lens — it gathered and concentrated any light remaining in the night sky. The result was that, from the position of a trout looking up, each fly on the surface was brightly outlined against the darkness all about it. It was a fabulously surprising result and it caused quite a stir.

The most common special interest in coarse fishing is specimen hunting, the tracking-down and targeting of big fish of different species.

The man credited with launching the specimen-hunting cult — and of stimulating interest in the carp, now the most widely and intensely pursued species of all — is the late Richard Walker. In the middle of the 20th century, the carp was viewed as being so wily as to be almost uncatchable. Walker, who had a brilliant scientific mind, great practical skills and steely determination, took the attitude that any fish, no matter how large or difficult, could be caught provided it was fished for in the right way, in the right place, at the right time, with tackle capable of hooking and landing it. It was an attitude that, through his writing and countless examples, enabled Walker to revolutionise coarse fishing almost single-handedly.

Quite early in his career, Walker decided to target carp as the ultimate challenge and, in 1952, he caught a leviathan — a 44-pounder that ended up in London Zoo.

Such was his application that in that season, from that water, he caught only five fish in 460 hours’ fishing, which is to say that he fished four unbroken days and four unbroken nights for each bite. To non-anglers that might appear obsessive behaviour but, of course, it was merely the commitment needed to achieve the desired result.

Dennis Flack, from Lakenheath, Suffolk, has become famous for a different kind of passion. Flack pursues little fish. Well, big little fish. He has made a speciality of catching the largest specimens of the tiniest fish in British waters. His dedication has given him the British records for the three-spined stickleback (an awesome seven grams), the bitterling (a shoulder-wrenching 21 grams), the bleak (a bone-grinding 114 grams) and the silver bream (positively hospitalising at nearly half a kilo).

And so it goes. In all likelihood, there are as many individual interests as there are anglers out there. There will even be some trying to photograph flies’ feet from underwater, at night. But — I will concede this — not many.

–– Brian Clarke’s angling column appears on the first Monday of each month.

Explore More Sport

• Athletics

• Boxing

• Cycling

• Sailing

• US Sport