Fishing Lines: Twin dangers of the crays

HYPER was the most boring pet I ever had. All he did was lurk under a rock and try to bite my fingers when I fed him. In the end I decided that even slugs would be better company, so I evicted him from the aquarium and chucked him in the Thames.

In those days, crayfish were quite common in the river around Maidenhead. But nowadays, invasions by foreigners have made the white-clawed or Atlantic stream crayfish an endangered species. It's disappearing so fast that the Joint Nature Conservation Committee, the National Rivers Authority and fisheries departments last week announced an action plan to save our only native freshwater lobster.

The Yanks are once again to blame. Oversexed, overweight and over here, the American signal crayfish carries a disease capable of wiping out the locals within days. Imported by crayfish farms, a few escaped (they are expert climbers) and quickly acclimatised to the clean, running water that English crayfish like. Being bigger and more aggressive, they drove the residents out or killed them by passing on a parasitic mould, which does not affect the American species.

There are now three varieties wandering around in British waters. The newest immigrant is the Turkish swamp crayfish. Quite how they sneaked in is a mystery. It's probable that a bundle were imported to be the star turn in a dish of gratin d'ecrevisses. Maybe the restaurant thought they had gone off, couldn't sell them or got nipped by one, and chucked the lot down the drain. Under normal circumstances, that would have polished them off faster than Desperate Dan, because most species can't survive in dirty water. But the Turks, which can grow as large as your hand, love such conditions. They are now in all the London park ponds (the Serpentine is stuffed with them) as well as Regent's Park Canal, and are probably crawling along your drains now.

Funny things, crayfish. The American dwarf crayfish is only an inch long, while the Tasmanian cray can grow to 8lb. There are more than 300 types and 250 of these are found in North America, with 29 species in Louisiana alone, where they even have crayfish races. The fierce Houma Indians who once roamed the state so admired this little crustacean that they adopted it as a battle symbol.

Over there, all sorts of creatures scoff them, from bullfrogs, mink and raccoon to man. Chub, trout and barbel are supposed to be partial to them over here, but my efforts with them as bait have been singularly unsuccessful. Old angling books assure you that fish find them irresistible. My research shows otherwise.

Trying to put them on a hook is bad enough (though I've since been told that the answer is to loop the creature with a pipe cleaner and attach the hook to that). Crayfish do not take kindly to such treatment and do their best to crunch your finger with their impressive nippers.

I made the mistake of using them as my secret weapon in an important competition on the Thame, a small Oxfordshire river. But I didn't catch a thing with them. It wasn't the crayfish's fault. After I had eventually hooked one and lobbed it to a likely spot, the rod top kept lurching round in a series of violent lags. It was impossible to tell whether a fish had taken the bait, or if it was the crayfish exploring its new surroundings. I am convinced that any chub or barbel in that particular spot fled when they saw this aggressive beast heading for them with its claws outstretched, as if looking for a rumble.

Maybe I should have just eaten them myself. They are certainly very tasty, though the tail is the only bit worth bothering with unless you like fiddling around for pinhead-sized mouthfuls from the legs. Still, if you want to help the Joint Nature Conservation Committee to stop the spread of the American crayfish (despite their inferior taste), what you need is a circular net and some kipper, by far a better bait than the recommended fish heads or chicken necks. Weight the net with stones and lower it, preferably on the bend of a river with a rocky bottom, at night. The last bit's very important because, as I discovered with Hyper, they are totally nocturnal. Check the net every 30 minutes. I've caught as many as 50 in a session.

You may find them so alluring that you can't bear to kill them. Can't see it myself, though I'm told they're a lot more active if you keep a pair of them as pets. At least that gives you the opportunity to call them Reggie and Ronnie.