Biologists recently captured and tagged one of the largest and oldest freshwater fish ever identified in the United States. This sturgeon, which measures 2.1 m long and about 109 kilos on the scale, could be over a hundred years old.
The lake sturgeon (Acipenser fulvescens) was captured on April 22 in the Detroit River in Michigan. It took three people to extract, measure and mark the fish, which was then released into the river. Jason Fischer, a biologist at the Alpena Fish and Wildlife Conservation Bureau (AFWCO), couldn’t believe his eyes.
“As we put it up it got bigger and bigger“, does he have declared. “In the end, it was more than double the size of any fish caught in the area before.“. His measurements are indeed impressive: 2.1 m long for 109 kilos on the scale.
It’s difficult to determine the sex of this sturgeon with certainty in such a short time, but based on its size, researchers suggest it is probably from a female over a hundred years old.
An emblematic species still fragile
Lake sturgeon are found in the freshwater systems of the east coast of North America. These fish spend most of their time at the bottom of rivers and lakes where they feed on insects, worms, snails, crayfish and other small fish which they catch by sucking up large amounts of water and sediment. This is referred to as suction feeding.
This species is currently considered threatened in nineteen of the twenty states in which it operates. Two decades ago, sturgeon stocks were depleted due to commercial fishing, which has since been controlled. Strict catch limits for recreational fishing have also been put in place.
These measures have borne fruit. In recent years, sturgeon populations have in fact gradually rebounded. The Detroit River now offers one of the healthiest populations in the country, with more than 6,500 lake sturgeons identified. Among them are perhaps other even older and imposing specimens hiding.
However, these fish still face other threats, such as pollution of waterways or the construction of dams and flood control measures that hamper their ability to move upstream to reach their spawning grounds.