Lucy Baring doesn’t have fish fever.

Communication with our son over the past six months has revolved, pretty exclusively, around four topics. His: the progress or otherwise of Southampton FC and his lack of success in the fishing arena. Mine: the length of his hair and the shape of his beard. When I think about his packing, this was entirely predictable as he left for South America with little more than one pair of shorts, two South-ampton FC T-shirts and a fishing rod. His hair was already longer than mine and he certainly didn’t pack a razor.

He spent the first three months working in Rio and, when I mention to a well-informed traveller friend that Will is planning to fish his way round the continent from about March, I’m told gently: ‘Isn’t he a bit late in the season for that?’ I have no idea and nor, clearly, does Will.

The first message read: ‘Sea full of fish, couldn’t catch for the life of me.’ This, I feel, maintains the optimistic fun-loving note of first endeavours. The next one said: ‘Just back from underwhelming fishing trip, not an amberjack in sight.’ A different note has crept in here, but nothing to make me doubt his fishing fervour isn’t fully intact.

The psyche of perpetual hope, of always wanting another cast, is different from my sister’s experience fishing in Scotland, when every other guest caught a fish or two but the salmon leapt over her line. She got up earlier and earlier, forgoing breakfast in order to spend longer on the water, flogging the river before falling, fishless, into bed at night.

This dogged determination without reward is merely step one toward the full fever. It takes several years to develop it fully, so that fishing becomes a reward in itself. Or so I’m told. My sister will never reach stage two, having hung up her rod. Permanently.

The next message from Will read: ‘Pls send money. Guide costs $250 with discount. Do I need to tip him?’ Personally, I found it crazy to blow a hole in the budget on a day’s fishing, but I’m not the one with a rod and a passion and who’d been guaranteed trout with weight in double figures. It’s his money and we sent it. ‘Caught 20 half-pounders,’ he sends later, with gloomy emoticons. Half-pound-ers are not what he was looking for.

Mindful that Will’s time abroad is running out, I email our travel expert to ask if he meant it about the fishing season, to which he replies: ‘Pretty peachy in Patagonia right now.’ Will is about 4,000 miles from Pata-gonia, I say. ‘Piranha in the Amazon very easy,’ he sends back. I don’t know if he’s joking, but I’m not relaying this information.

Nor do I relay that Zam has just caught a trout on the Nadder, which, when laid nose to nose with the dachshund on the riverbank, was about the same length.

‘Maybe he needs one of these,’ I tell Zam as I read about a drone that’s been developed by Roger Borre in the Netherlands. It lowers an underwater camera that feeds images back to the angler, takes line, bait and weight out to a prime spot, detaches them from the drone when it hits the sea/lake/river bed and quite possibly pops the bait into the fish’s mouth. I don’t know because I stopped reading at that point. Borre by name and, as far as fishing’s concerned, by nature.

So now Will’s nearing the end of the trip, during which he’s fished in Argentina, Peru, Brazil and Colombia with very little success and we’ve received this: ‘Just tried spear-fishing. Harder than it looks.’ I read this and wonder if the fishing fever has taken a bit of a knock when I get his last message, within seconds: ‘Pls send dates when Casp and I can go fishing on return to UK.’

I don’t send dates. ‘When is the beard coming off?’ I reply.