Northern Minnesota and New Orleans, origin and terminus of the Mississippi, share more than a relationship with an epic river. In the waters surrounding both ends, crayfish swarm.

Southerners have long demonstrated their fondness for crayfish (known also as crawdads or, more affectionately, mudbugs) with a history of well-debated recipes. Through the captivating aroma of their best étouffées and gumbos, and in the rusty, honeyed crust of rice that lines the jambalaya pot, this feisty little bottom feeder has earned its spot in culinary heaven.

Back in Minnesota, the publicity for crayfish as an edible has been slim. Sometimes we use them for fish bait, although for the most part we just step over them -- by the thousands.

But local crayfish had better start watching their backs. Judging by the popularity of my crayfish boil last week, I predict that the protected status the critters have enjoyed here will be ending soon, because they're easily the finest crayfish anyone has ever tasted -- in fact, the only good-tasting shellfish native to the Midwest.

Lazily shucking our way through the mountainous pile on the picnic table, we found that they go down pretty easily, especially when slicked up with a spicy mayo. As sweet and tender as lobster and tasting as clean as the lake from which they were pulled, the ruby-red crayfish shared the pot with spicy andouille sausage, new potatoes, corn and a few fistfuls of dill and spices.

As good as they are, it's nearly impossible to eat too many. Crayfish are to long summer days what shelling salted peanuts are to the ballgame or cracking whole nuts is to Christmas, more like grazing than sitting down to a proper dinner. It's putzy work, but a crayfish boil isn't just a meal, it's a celebration of a seasonal delicacy.

Real aficionados separate the heads and suck out the juices. All potential squeamishness disappears when you find that the head yields a pleasant mouthful of smoky, golden pot juices.

The Rusty invasion

Crayfish thrive in cold, clean spring-fed lakes, of which there are many in the glacial aftermath covering northern Minnesota and northern Wisconsin. So it should come as no surprise that the Upper Midwest's numerous lakes and streams hold a significant population of freshwater crayfish. After all, ours is arguably some of the country's most pristine water, and probably the coldest.

In the 1960s, a rogue crayfish (Orconectes rusticus, or Rusty for short) began to show up in our lakes and creeks. Natural resources people speculate that they came here as bait from Indiana and entered our lakes via the fisherman's habit of dumping their leftover bait back into the lake.

Since then, the Rusty invasion has increased the population of local crayfish many times over, repopulating at such a rate that the Minnesota Department of Natural Resources has classified them an exotic, invasive species.

The good news is that the Rusties are better eating than our native Orconectes virilis. Rusties usually grow larger and have bulkier, meatier claws.

The bad news is that these crayfish dominate our native ones, eat fish eggs by the dozen, and change the delicate aquatic balance in our lakes. Rusties spend their days in lakes and creeks felling vegetation at its roots, much as a logger might clear-cut a tree plantation. And as feisty as they are, Rusties often successfully evade their predators.

I think our duty is obvious.

Save the fish! Eat the crayfish!

I grew up a few miles from the headwaters of the Mississippi, and I remember crayfish from my childhood spent wandering in rocky, shallow waters. If lucky enough to corner one, we'd hold sticks at its belly, teasing the poor little creature until, finally fed up, it drove us back with a wild frenzy of snapping. The thought of eating them never crossed our minds.

Until now. Related most closely to the lobster but with other family members including shrimp, langoustines, spiny lobsters and various other crawling crustaceans, crayfish taste a lot like their kin and don't need much embellishment. A simple squirt of lemon or a dip in melted butter is usually enough.

Yet many cultures celebrate the crayfish harvest more decadently. The French adore them, their ecrevisses, whose intense, musky-sweet flavor mingles so well with cream and butter. They poach, peel and fold them into luxurious mousses and soufflés. They pound their shells to a pulp and fashion glorious sauces, such as Sauce Nantua, a savory, saline cream the fiery hue of late sunset.

The Finns and Swedes throw crayfish parties that linger on into the early hours. They boil them in a vat of beer- and dill-spiked broth, and then chill them. Served with rye bread and lemon, the feast is completed with shots of ice-cold aquavit or sips of light ale.

Leftovers become salads and sandwiches

I like to flaunt our local abundance by serving them in massive quantity. The steaming pile of red mudbugs is not only impressive, but it also ensures leftovers, which migrate happily into my salads, sandwiches and morning scrambles for the rest of the week.

While my boil recipe pays respect to the Creoles, whose andouille sausage contributes both chile and pork (always welcome), I do inject a little Minnesota to the pot with heads of crown dill, an addition that strikes a comforting, familiar note in the hearts of most Scandinavian Minnesotans.

Speaking of Scandinavia, when I sent a photo of my 25-pound boil the other day to a friend in Helsinki, his response was ridden with exclamation points. In present-day Finland, a crayfish pile of such proportions would be about as vulgar a display of wealth as a mountain of porterhouse steaks.

Not only can we throw minnow traps into the local lakes and drag up enough for lunch, but we can buy them off the dock of a northern trapper for just $2.50 a pound. Which means that, pound for pound, our crayfish are cheaper than ground sirloin.

Amy Thielen, formerly of Minnesota, now lives in New York City.