Monday, February 06, 2023

Sturgeon outlived dinosaurs and the Chicxulub asteroid; now they must contend with mankind, will they survive?

Atlantic sturgeon were once plentiful, but now may face extinction.
(Photograph by Joel Sartore, National Geographic Photo Ark)
Atlantic sturgeon have been swimming in North American waters for the past 10 to 15 million years. Sixty-six million years ago, when the Chicxulub asteroid hit, eliminating about 70 percent of species on Earth, Acipenser oxyrinchus oxyrinchus survived, reports Andrew S. Lewis of The New York Times. "Last year, however, the International Union for the Conservation of Nature called sturgeon "the animal group most at risk of extinction in the world," adding, "Humanity has reduced this ancient and enduring fish to such a fragile state speaks to the force of the latest impact event to remake the Earth — our own presence."

The North Atlantic sturgeon's demise began on the lower Delaware River estuary in the mid-1800s: "During the spring spawn, an estimated 360,000 adults thronged the reach that marked the brackish threshold between bay and river," Lewis writes. "Theirs was the roe prized by the Russian czars, whose brokers at one point paid more than $1,400 in today’s dollars for a single female Atlantic sturgeon. During the fishery’s peak, in 1888, 16,500 Atlantic sturgeon — they can live 60 years and grow to 14 feet and 800 pounds — were 'harvested,' or killed. Most were female, and the millions of eggs that each could produce during a spawn never made it into the water within which they were meant to hatch."

Lewis reports: "Because individuals from different rivers do not commonly interbreed, their homing instinct has produced populations whose genetics are unique to the waterways of their birth. In 2012, the species became protected under the Endangered Species Act. At the time, researchers estimated that the Delaware population consisted of 300 or fewer spawning adults per year."

In the Delaware estuary, "strikes by vessel hulls and propellers are a threat to Atlantic sturgeon across their range but responsible for half of all adult deaths . . . dredging is known to be especially harmful for Atlantic sturgeon," Lewis reports. A study by Dewayne Fox, a fisheries biologist at Delaware State University used Delaware’s data on vessel strikes to "calculate how many additional fatalities were going unnoticed," and his estimates were unsettling.
  
"In a population with so few adults, it signaled an alarmingly high rate of deaths," Lewis writes, adding that the study results were held for review by the Northeast Fisheries Science Center: In June 2021, a National Marine Fisheries Service biologist who was writing the biological opinion on proposed port projects "said he was considering using Fox’s study as part of the best available information on vessel strikes. . . . . but when the BiOps were released, Fox learned that NMFS had instead relied on a decade-old study from the James River in Virginia."

Meanwhile, dredging began for a "wind port" to serve turbines planned off the coast, "and would continue to do so for several months," Lewis writes. "While there were no reports of sturgeon killed during the work, the new port would mean more ship traffic for years to come."

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