By Emma Fass, Summer Science Writing Intern
“It kills me to see a five-pound fish floating with seagulls poking at him because he can’t get underwater,” says Skip Feller.
Feller has been working on deep-sea charter boats since his father bought his first boat when Feller was 10. Today, he captains the Rudee Angler out of Virginia Beach, a 30-passenger head boat. He’s witnessed a phenomenon where live fish are released, but they are too bloated to submerge themselves. It’s called barotrauma.
When anglers quickly reel in a fish from deep depths, the gas inside the fish’s air bladder expands. If the fish is undersized or the species is out of season, the angler will release it, but the fish can’t swim away.
The expanded air bladder acts like an inflated pool float; pushing a float more than an inch below water is hard enough without trying to submerge it 300 feet. This keeps the fish at the surface where it’s easy prey.
With funding from National Oceanic and Atmospheric Administration, Virginia Sea Grant extension partnered with Captain Feller and Sea Grant-industry partner teams in New Jersey and North Carolina to develop and test new fishing gear—descending devices—to bring released fish below the surface and improve survival.
The deck of a charter boat is crammed with activity—and very little free space. Between 30 and 70 anglers fish simultaneously from spaces along the side of the boat, and they pay a premium to be shuttled to the best offshore fishing spots.
These are hard-core fishermen, says Feller. His customers sign up for a 17-hour trip with one goal in mind: “They want to catch fish to take home and feed to their families.”
If researchers want a descending device to work for these businesses, certain conditions need to be taken into account. The device needs to allow anglers to have space to fish, and it must be manageable by the already busy crew. This means designing a device that’s compact and easy for a mate to hand-deploy over the rail, without taking significant time away from supporting customers on board.
Another key factor: the descending device would need to accommodate and lower multiple fish to keep up with the high volume of fishing activity.
Single fish descending devices already exist. Conservation minded fishermen who fish from their own boats might already be using these kinds of descending devices, says Feller. But on charter boats, where a dozen or more fish might get pulled in at the same time, a single-fish descending device wouldn’t work.
With input from captains, the research team designed several different devices and tested the prototypes. For their study this summer, they settled on testing a weighted hoop-net device.
The device is a tubular net, with one end closed and the other open. As anglers catch fish, they put the ones they want to release into the net. To release the fish, the hoop-net is dropped overboard. The device falls through the water with the opening facing down; the weight of the hoop pulls the net down, fish and all.
“Remember, each fish is like a balloon and has a buoyancy factor that must be countered,” explains Bob Fisher, Virginia Institute of Marine Science (VIMS) extension staff affiliated with Virginia Sea Grant and one of the researchers on the team. The hoop must weigh enough to sink despite the little fish “balloons” floating in the net. The fish’s air bladder recompresses as it is pulled down, and the fish regains the ability to swim out on its own.
The team tested the design on several species including blueline tilefish, triggerfish, blackbellied rosefish, and black sea bass—which they encountered the most.
Black sea bass proved a good species for testing the descending device: It’s slow-growing, reaching maturity between 1-3 years of age, and anglers have a good chance of reeling in an under sized fish. Black sea bass also tend to display symptoms of barotrauma: bulging eyes or organs protruding from the mouth or gills.
The researchers descended a total of 227 fish. Susanna Musick, VIMS extension staff affiliated with Virginia Sea Grant and one of the researchers on the team, credits Captain Feller with the success of these early trials.
“Skip and his captains and crew really made our project possible,” she says. “His feedback in terms of device development and his experience with Virginia’s deep drop fishery was invaluable.”
Of those, 161 fish were tagged and will be monitored by tagging programs in each state. Recapture of those fish will help researchers estimate how well descending devices improve survival.
During trials, researchers also gauged customers’ opinions about the devices. Although almost three-quarters of passengers were not familiar with the term barotrauma, the team discovered that anglers support the research. At least 90% said that they would support a captain who used a descending device.
While the trials were promising, there’s still work ahead.
“The education and outreach component is critical for [this project] to work.” Fisher says, Continuing to teach anglers about barotrauma and the benefits of using recompression devices may slowly win over more users.
Feller agrees that education is important for the anglers on his boats.
“I think having Susanna and the people at VIMS out during the trials helped the cause, because they knew how to explain this so [the customers] knew it was a good idea,” he says. “Down the road, it’s going to be harder for us to sell it without them there.”
One thing that could help Feller and other captains sell their customers on the benefits of these devices could be through improved regulation. On the West Coast, for example, anglers who use descending devices receive benefits, like access to closed areas. In Virginia, Feller expects that shortening the closed season or increasing the number of fish an individual could take home might help encourage customers and captains to support using the devices.
Before a regulation change could even be an option, the team will have to demonstrate that the device did improve survival; that won’t be known until those tagged fish are recaptured and reported.
“I know it won’t change overnight,” he says, “but we need to get these kind of devices and the knowledge of why we need to do this out there.”
You can find a copy of the final report online at http://www.vims.edu/research/units/centerspartners/map/recfish/docs_recfish/MRR2015_12.pdf
For more information, contact Susanna Musick, firstname.lastname@example.org