Female sturgeon caught in James suggests fall spawning run
Discovery could lengthen time that fish is protected if it is declared an endangered species
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For years, scientists were skeptical about whether any sturgeon spawned in the James River. Now, they know the giant fish not only spawn there, but a recent discovery suggests they may have two distinct spawning runs on the James.
Biologists on Sept. 9 captured a fish leaking eggs - only the second confirmed female caught on the James in recent history.
The late summer discovery of a "post-spawn" fish adds a little more credence to a suspicion fishery biologists had that while some James River sturgeon spawn in the spring like most other fish, others make a separate spawning run later in the year, said Greg Garman, director of the Center for Environmental Studies at Virginia Commonwealth University.
If the catch ends up confirming the suspicion, it could prove more than just an interesting biological discovery.
The National Marine Fisheries Service, a part of the National Oceanic and Atmospheric Administration, last year recommended that Atlantic sturgeon in the Bay - and along most of the East Coast - be listed as endangered under the federal Endangered Species Act. A final decision by the NMFS is expected this fall.
If the fish is protected under the act and it is confirmed there are two spawning runs, the discovery could lengthen the amount of time that protection for spawning age fish would be in place each year. Protective regulations might include rules to protect sturgeon from fishing or ship strikes.
"If there really is a fall spawn, that is critical to know in terms of implementing a recovery plan for what we think is about to be a federally protected species," Garman said. "So it is more than just an academic exercise."
The 5.5-foot fish was caught by a team led by VCU doctoral student Matt Balazik that captures and tags sturgeon near the confluence of the Appomattox and James rivers. The biologists believe that area may be a staging ground where the fish, migrating upstream from the ocean, adjust to changing water salinities before moving to freshwater spawning areas.
Balazik noticed that one of the fish caught in the biologists' gill nets appeared to have an indented stomach. On closer inspection, he saw that the vent where eggs would be released appeared reddened. When he checked in the tube, he found eggs, which the biologists believe were remnants from recent spawning.
The find bolstered suspicion among some biologists that the river supported a distinct, late spawning run. In the three years of the gill net survey, the majority of the more than 100 adult sturgeon captured have been in the fall. Besides eggs found in the female, many males caught in the fall have been ready to release sperm.
"That begs the question, why are adult reproductively active sturgeon staging here and running up into freshwater if not to spawn?" Garman said. "Everything we have seen up through this year would be consistent with a fall spawning event."
He acknowledged that finding a post-spawn sturgeon, while suggestive, is not definitive proof of a fall spawning run. "I would rather have found the eggs fertilized on the bottom of the river, which would prove spawning in the James," Garman said.
The eggs retrieved from the fish will be examined by a sturgeon expert to determine if they are mature eggs, and if the female likely spawned in the James where she was found and not some other river.
Most anadromous fish - species that live most of their lives in the ocean but return to their natal rivers to spawn - spawn in the spring. But fall spawning runs have been noted for Atlantic sturgeon in the Cape Fear River of North Carolina and other rivers to the south. They have never been documented farther north, where later springs and earlier falls restrict the potential spawning season.
"It would certainly be unique in the mid-Atlantic," Garman said. "And there is no suggestion of fall spawns farther up the coast."
Atlantic sturgeon are the largest fish native to the Chesapeake, and historically reached lengths of up to 14 feet and weighed up to 800 pounds. Once abundant, their populations were decimated by overfishing in the late 1800s and never rebounded. Poor water quality, loss of habitats, continued bycatch in other fisheries and mortality caused by ship strikes are all ongoing threats to the remaining population.
Until recently, sturgeon were thought to be extinct throughout the Bay. But in the last decade, biologists have confirmed that a reproducing sturgeon population has survived in the James River, based on the periodic discovery of small sturgeon too young to have swum into the river from someplace else.
Actual spawning has never been seen in the James, and scientists are uncertain exactly where sturgeon spawning areas are located. Only two confirmed females have been caught on the river, in part because female and male sturgeon look so similar it's hard to tell the sexes apart.
The other female sturgeon was found this spring, when Balazik discovered eggs inside a sturgeon caught in a fisherman's gill net while tagging the fish. After its capture, though, the fish appeared to have fled downstream rather than continue its upstream migration.
Now, the small vial of sturgeon eggs from the fish captured in September could be the only Chesapeake Bay sturgeon eggs in existence. Biologists in Maryland have reared Atlantic sturgeon in captivity, but they have used eggs from sturgeon that came from outside the Bay.
"They are the only Virginia sturgeon eggs, so they are certainly worth their weight in gold," Garman said, adding the eggs are in a "very secure" location.
- Category: Fisheries
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