May 11, 2021 — This spring marks a decade since New Jersey’s Bureau of Marine Fisheries first deployed acoustic receivers to track the migratory patterns of the endangered Atlantic sturgeon in the Delaware Bay. For the researchers tasked with monitoring this fragile, prehistoric fish species, the past 10 years have been an exercise in hope — and occasional surprise.
“There are signs that the population has started a slow recovery,” said Brian Neilan, a senior fisheries biologist who leads the monitoring program for the bureau. “At least relative to the numbers when the [Atlantic coastwide] fishing moratorium on sturgeon went into effect in 1998.”
In mid-March, Neilan and his team deployed 19 acoustic receivers throughout the New Jersey side of the bay, from Cape May to Egg Island Point, in Cumberland County. The receivers pick up frequencies pinged from sturgeon and other fish implanted with radio tags that are similar to the microchips used for household pets. “It’s like E-ZPass for fish,” said Neilan.
On April 12, the first dataset was pulled from the receivers. Of the over 600 detections recorded, 66 came from just five sturgeon. “Those numbers are pretty on par for what we see during March and early April,” Neilan said. “May is typically when we get the most detections, because that’s when the sturgeon are using the bay the most, to go up to their spawning grounds in the river and then come back down and back out into the ocean.”
Like other depleted, culturally significant fish species in the Delaware Estuary, sturgeon are anadromous, meaning they spawn in fresh water, where they remain for the first couple years of their life before migrating to the ocean.