The reason for this is that as the temperature rises, water holds less dissolved oxygen, but at the same time a trout's demand for oxygen increases. The water at the surface is hotter than that further down, so fish dive deep, rarely venturing to the top unless they have George Hamilton tendencies. Trout are cold-blooded creatures so their body temperature, and therefore their metabolism, appetite and energy levels are all dictated by how hot or cold the water around them is.
Just like us, when it's too hot or cold they get lethargic and their need for food diminishes. They prefer it at 7-9C, although they can survive in water above 20C if it's oxygen rich. Trout can only survive in water with little oxygen if it's also very cold when there is also less carbon dioxide, because like us (so many similarities) this gas is not their friend.
Trout breathe in through their mouths. They suck in water which is passed through the gill filaments and out through the gill slits at the sides of their little faces. These filaments are like sieves (actually they remind me of the insides of old fashioned radiators), they absorb the oxygen from the water and pass it into the fish's blood and the carbon dioxide is chucked out through the gill slits.
This is why, in case anyone was silly enough to wonder, a fish's gills are like a man's testicles and should be treated with respect and delicate care at all times. Just as you would not stick your hand down a strange man's trousers, never never jam your fingers into a fish's gills to levy a hook out of its mouth.
Anyway, the point of all this is that, due to hotness, I have not been fishing for a while. Last Sunday I decided to go to Gamlingay, once the scene of my first fishing expedition in this country. But my fishing buddy told me it was closed, due to it being so hot. When it is that sunny the only place to go is to a big reservoir, take a boat out and fish deep where the water is colder. I really didn't fancy going out on a boat this particular day (regular readers will know that I am a bit of a wuss in this respect) so I decided to stay home.
My first trip to Gamlingay had been very different. It is not a very large lake, just a few acres. Nevertheless, for my first venture into a boat it was a big deal. As I remember it took at least half an hour to get me into it, with Pete jumping up and down in the boat saying: "It's quite safe". Finally, one foot left the jetty and the other dropped down into the boat and I sat down and clung on. Eventually, though, I got very brave, very quickly - the hallmark of the deeply foolish (this does not end with me falling in) and started fishing standing up.
Depending on who you listen to this is either okay or a prelude to death by drowning. But the important thing is that I hooked a fish almost immediately. Despite Pete telling me that it would be like "getting an electric shock" I still wasn't prepared for the take.
I immediately handed the rod to Pete who tutted, very loudly, and took over. I cried when I saw the fish, that had battled so bravely, brought to the net. For half an hour I sat in shock. I had never seen a creature fight for its life outside the television and it was humbling. For 30 minutes I really thought I might become a vegetarian. But my Italian genes were stronger, and I started to think of salami, coppa and bacala and picked up my rod again.
Within seconds I was into another fish which I netted and priested myself: my first rainbow trout. How much it weighed didn't matter. Pete said it wasn't normally this easy (it rarely has been again) but for the rest of the afternoon I caught more fish than I knew what to do with. First fishing trips are often like that, it's when you start caring that you stop catching them. Just like boys.
n Little Heath Farm, Gamlingay: 01767 650301.