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25 juillet 2021 7 25 /07 /juillet /2021 05:38

L'Esturgeon des Grands Lacs, qui peut atteindre 2m de long et vivre 150 ans, est de retour, après avoir subi un effroyable massacre au XIXème siècle*, puis bénéficié des soins particuliers de quelques scientifiques résolus et passionnés depuis quelques décennies.

MORT... Commercial fishing, which took off in the Midwest in the early 1800s, saw sturgeon as massive nuisances that shredded nets meant to catch other fish. Boats eventually caught lake sturgeon strictly to stack the carcasses on beaches to burn. The perception flipped in the 1860s: Smoked sturgeon meat and the fish eggs, better known as caviar, became popular menu items. Fishers in the Great Lakes pursued the fish even more aggressively. From 1895 to 1905, the numbers in Lake Eerie fell 80 percent.

Construction projects damaged sturgeon populations too. Dams sliced migration pathways into pieces. Waterways carved out to allow bigger ships or to provide construction materials lost their pebbly bottoms, the preferred hiding places of newly-hatched sturgeon. In the St. Louis Watershed coursing through Minnesota and Wisconsin, white pine logging disrupted migration.

Compounding harms to lake sturgeon have kept numbers low for the past century. The species is considered threatened in 19 of the 20 states in its historic range, and many of its ancient habitats now lack the fish completely. In fact, estimates of what rivers and lakes the sturgeon should be in might be missing bodies of water where the fish disappeared from before people started documenting its whereabouts.

... ET RENAISSANCE. Besides being integral pieces of their native ecosystems, the fish are culturally and spiritually important members of the landscape for the Ojibwe. And higher lake sturgeon numbers could help maintain invasive species populations that have proliferated in the same areas.

In the 1980s, biologists set out to accomplish what their predecessors had failed to do in the late 1800s: Bring lake sturgeon back to their habitats. Restoration efforts kicked off in the Mississippi, Missouri and St. Louis rivers. After finding healthy sturgeon populations to tap into, biologists collect eggs and sperm to breed the fish in their labs before releasing them into a new river. And then the restoration team repeats the process for 20 years or more.

 

Voir le détail dans l'article de Leslie Nemo publié par "Discover Magazine", avant-hier.

https://www.discovermagazine.com/environment/how-scientists-are-bringing-back-sturgeons-fish-that-once-swam-with

* Le massacre a commencé à l'issue du percement du Canal Erié (1817-1825) qui permettra le développement prodigieux de la ville de New-York. Les bateliers de l'Erié sont évoqués par Herman Melville au chapitre 54 de "Moby-Dick" à travers le personnage archétypal de Steelkilt...

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