By Emma Fass, Summer Science Writing Intern
In May 2013, NOAA Fisheries Southeast Regional Office declared black sea bass were no longer overfished and the population was successfully rebuilt—but that’s not the end of the story.
Bob Fisher, Virginia Institute of Marine Science extension staff affiliated with Virginia Sea Grant, spent years working with industry to reduce fishing mortality in black sea bass. In 2002, Fisher and Virginia waterman Jim Dawson tested new fishing gear aimed at reducing accidental catch of young, undersized black sea bass. Today, Fisher is researching black sea bass, but this time for the recreational fishery. (More on this project will be posted on Thursday.)
For Fisher, both of these studies are aimed at improving survival of young fish. While his previous work aimed at stopping these young fish from getting caught in the first place, his newest work involves releasing fish so they can survive. Ideally, released fish would survive to reproductive age and contribute to the population.
“I feel like I’ve come full circle,” he says.
Catch: Improved Fishing Gear
More than 10 years ago, Fisher and Dawson tested traps that would catch fewer undersized fish. The team tested a 2-inch square mesh, an increase from the standard 1.5-inch mesh. This change allowed sublegal sized fish to get out of the trap before it was brought to the. The result was a reduction in catch of undersized bass by about 70%.
In 2005, black sea bass was considered an over-fished species along the southern US Atlantic.
The idea of providing multiple escape vents in traps, along with catch limits and other management measures, were incorporated into the South Atlantic black sea bass fishery management plan in 2006. By 2013, the species recovered.
Release: An Additional Concern
While the traps Fisher and Dawson tested reduced catch of sub-legal fish, some small fish still get in there, and Fisher says tossing them back isn’t always enough.
When deep-water fish, like black sea bass, get pulled up to the surface, gases inside the fish’s swim bladder expand until the fish balloons. This condition, called barotrauma, prevents the fish from swimming away when thrown back. As the gas takes time to re-compress, these fish are floating on the surface attracting predators.
Commercial and recreational fishermen have observed barotrauma in fish they try to throw back.
Survive: Researching a New Device
This year, Fisher and colleagues from Virginia, North Carolina, and New Jersey started researching a descending device that charter boats could use to help up to 20 fish recover from barotrauma at a time, an improvement over current devices that can handle 1-3 fish at once. Decending devices lower fish experiencing barotrauma back to depth, where their swim bladders return to their normal state and the fish can again swim.
These multiple-fish descending devices were tested on recreational head boats, where many anglers fishing together bring a large number of fish in at a time. But, Fisher says, “I see a commercial application for this work as well.”
Check in next week for more on barotrauma and testing a new descending device.
