https://fivethirtyeight.com/features...asive-species/

First paragraphs:

By Maggie Koerth-Baker
Oct. 16, 2018

On a rocky strip of Lake Superior beachfront, the rites of spring begin at dusk and involve fish. Lots and lots of fish. Every year, like clockwork, slender, silvery rainbow smelt, each no longer than your hand, return from deeper waters. They arrive just as the crust of winter ice on the water breaks apart, looking to spawn in the frigid creeks that run out of the hills north of Duluth, Minnesota. For three or four nights, maybe a week if youre lucky, thousands of smelt jostle their way out of the lake.

And thats where the humans are waiting.

On this night in early May, on the narrow mouth of the Lester River, there are only about a couple dozen people present. They stand around, bundled in hooded sweatshirts layered under thick rubber overalls that cover their bodies from toe to nipple. The smelt have not yet arrived and the beach is quiet. Waves lap the shore. Someone kicks a rock.

But 40 years ago, smelt fishing on the Lester River was something else entirely. €œThere were people all over the place, bumper to bumper on London Road,€� said Don Schreiner, fisheries specialist with the Minnesota Sea Grant. These now-tranquil shores were once home to a circus tent that housed an all-night smelt fry and a party atmosphere so wild that Schreiners parents wouldnt even take him and his siblings down to the beach. In addition to hangovers, the smelt also brought a tourism industry. There were professional fishermen catching and selling smelt. It was a huge cultural event. €œAnd then,€� Schreiner said. €œIt crashed.€�

Starting around 1979, smelt numbers in Lake Superior plummeted. In 78, commercial fishing companies took in nearly 1.5 million pounds of smelt. A decade later, the haul was 182,000 pounds. There is no commercial smelt fishing on Lake Superior today. But because the smelt in Lake Superior are an invasive species, their decline is actually a sign that the lake is becoming healthier, ecologically speaking. From a cultural and economic perspective, though, the North Shore isnt what it was. So is the decline of smelt something to celebrate? And if so, who should be throwing the party?...

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