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Hatchery-Raised Fish Start a New, Wild Life

These cobia and spadefish hatched to help scientists refine the larvae production process and determine nutrition needs. As tagged fish, they will have one last opportunity to contribute to science as they live out their lives in the wild.

Victor Andrade, VT aquaculture intern from Brazil, releases a tagged cobia into the Hampton River. ©Janet Krenn/VASG

By Janet Krenn

It was a science bonus on Monday at the Virginia Tech (VT) Virginia Seafood Agriculture Research and Extension Center in Hampton. Extra fish that had been hatched and raised over the last year for research were tagged and released by VT and Virginia Institute of Marine Science (VIMS) staff. Originally hatched to help scientists refine the larvae production process and determine baseline nutrition requirements, as tagged fish, they will have one last opportunity to contribute to science as they live out their lives in the wild.

In all, 18 cobia and about 200 spadefish were released.

“It’s tremendous that we’ve been able to do this together. We wouldn’t have been able to do it ourselves,” says Mike Schwarz VT Aquaculture Extension Specialist, whose team hatched and raised the cobia and conducted nutrition trials of both fish types. “We have the resources to produce and keep thousands of fish of different species, but we don’t have the background, experience, or permits to release the fish back into the wild. By collaborating, we’re able to integrate capacity, infrastructure, and expertise.”

One of the day’s experts was Susanna Musick, VIMS Marine Recreation Specialist, who works with the Virginia Marine Resources Commission to train volunteer anglers to use tagging guns and record data as part of the Virginia Saltwater Game Fish Tagging Program. Musick and Dan Sennett, Marine Aquaculture Specialist at VIMS who hatched and raised the spadefish last year as part of a Virginia Sea Grant-funded study, tagged fish.

For Musick, the collaboration means she’ll be able to gather data about age-specific behaviors, such as migratory patterns, in cobia and spadefish.

“Given that we have a known age and length for the fish at the time of the release, future recaptures will also give us growth data for known-age fish, something we aren’t able to do with wild-caught fish normally tagged in the Virginia Game Fish tagging Program,” said Musick.

Once the were tagged, interns and VT staff transported the cobia in wet towels to the Hampton River, and loaded buckets of spadefish into a large haul box aboard the Sea Breeze.

“Go, fish!” Victor Andrade encouraged a cobia he just released. Andrade, from Brazil, is one of VT’s aquaculture interns along with Amandine Lecrenais from France, Hannah Mark from Canada, and Luiz Teixera from Brazil. As the fish he just released hung motionless just below the surface facing the wall next to which it was dropped, Andrade chuckles “He’s probably not sure what to do. He’s wondering, where is the tank?” Apparently not up to the ridicule, the fish turned and swam away.

Andrade’s comment was in jest, but it gets to another question: Can these animals, born and raised in a hatchery, survive in the wild?

This will be the first time the team tagged and released hatchery-raised spadefish, but evidence from previous tag-and-releases shows that cobia can make it in the wild. In August 2011, one aquaculture-raised cobia was recaptured after three years at large. More recently, a less than one-year-old cobia tagged and released this spring through a similar collaborative tagging effort was recaptured earlier in the summer. At the time of recapture, it was 30% bigger.

Although it’s common for fish to grow rapidly in their first year, Schwarz says, “It shows that the [released] fish are finding enough food to eat and keep growing.” A seemingly small feat, but quite impressive considering foraging for food is not part of the repertoire of a tank-raised fish.

As for the fish that were released this week, the team is hopeful that the fish will settle in to their new environment.

“Everything went really well,” said Schwarz. “There was minimal handling and stress on the fish, indicative of the expertise of the tagging people knowing what they were doing. The fish were healthy, indicating the growers know what they were doing… We put the fish in the water, and they zipped away… just like a healthy fish should.”

Up until the point those fish zipped out of site, they had relied on their human counterparts for their survival. Now it’s up to them.

Watch Aquaculture Interns and VIMS and VT Staff Tag and Release