By now the Atlantic sturgeon that made their way up the James River for their fall spawning run have turned around and headed back out toward the ocean. In the past, this is where our knowledge of their whereabouts would end. Researchers knew they went north, generally, but where, exactly? And how quickly? At what depth? Where did they stop along the way?
For the first time, however, some of those questions could be answered.
Back in September, VCU researcher Matt Balazik chose three male sturgeons that he netted in the tidal James and inserted satellite “B-WET” tags under their dorsal scutes. (B-WET stands for NOAA’s Bay Watershed Education and Training program. That’s where these tiny, titanium tags came from.)
“This is kind of a first…in 2003 they did a couple in the Hudson River,” he said. “But no one has done it since then (with adult fish) and with the more recent technology. They did some juveniles up in Canada…and they were only designed to stay on for a couple months.”
Balazik explained that the tags are programmed to pop off at a certain date (Aug. 11) or if certain conditions occur: “If the fish stays at a certain depth for a week straight, it’ll think that the fish is dead. It’ll corrode and release. If it goes over a depth of 3,000 meters, it’ll ping off and release.”
Sadly, for one five-foot-long male, that’s exactly what happened recently. Balazik was hoping not to have to retrieve a tag so soon, but on November 13 he and VCU professor Anne Wright found one on the beach next to the Lynnhaven Pier. It had been on the fish for about a month. The tag popped off automatically when the fish stayed at the same depth (give or take, considering tidal variations) for over a week.
“We have beautiful data in the river, then it’s out in the ocean and everything is going well,” Balazik said. “It goes from moving all over the place to doing a slow up and down… I fear it was a ship strike.”
So, now two males are left with tags in them. Every 10 minutes or so, the tag collects data on depth, water temperature and location, and stores it in a tiny memory card. But Balazik can’t collect that data until the tag surfaces and can transmit to the satellite — hopefully when it’s scheduled to on Aug. 11.
“That’s why it’s so nerve wracking,” he said. “You just have to sit here and wait either until something bad happens and the tag pops off prematurely, or you wait until you get some emails from the satellite on Aug. 11.”
In the meantime, Balazik imagines the kind of answers these tags will provide researchers for the first time.
“I want to know where it goes over winter…I want to know, (when) it comes back to the (James), it if all of a sudden, if its way up in Maine, is it like, ‘Oh crap, it’s time for me to go spawn,’ and makes a huge bolt down in like a week or so. Or does it meander down and just turn in.”home page