STEVE INSKEEP, HOST:
This next story explores the health of fish. Recreational fishermen catch and release - part of the sport. You bring up a fish but then let many of them go. That is supposed to be good for the fish, but fish brought up from far below the surface often die, even if they're handled gently and released quickly. NPR's Jon Hamilton reports on a discovery that is allowing those fish to survive.
JON HAMILTON, BYLINE: Here's the problem - even fish get the bends. Chris Lowe, a marine scientist at Cal State, Long Beach, says the reason has to do with something called the swim bladder. It's like a balloon that helps fish control their buoyancy.
CHRIS LOWE: When you catch that fish and you rapidly bring him to the surface, that gas in that balloon rapidly begins to expand as the pressure from the water decreases. So when a fisher brings them up, they're looking at the fish. Its eyes could be popped out of its head. Its stomach is pushed out of its mouth, and it looks absolutely horrific.
HAMILTON: Lowe explains this as we head out into the Pacific on a boat named the City of Long Beach. About a dozen recreational fishermen are also on the trip. Lowe says when fish experience what's called barotrauma, they look like they're dead. But they're not. He discovered this about 10 years ago while trying to implant tracking devices in California rockfish. These rockfish often live hundreds of feet down, which is a tricky place to perform minor surgery. So Lowe's team brought the fish to the surface and then quickly sent them back down in cages.
LOWE: I thought for sure - two days later, we bring the cage back up, the fish would be dead. We brought the cages back up. All the fish were alive - open the cage doors, let the fish swim out.
HAMILTON: So deep-water fish could survive a trip to the surface if fishermen had a way to send them back down in a hurry. The question was how. Lowe says scientists didn't know.
LOWE: So it was really fishermen that came up with many of the ideas on how to get these fish back down. And they've actually come up with some ingenious ways of doing it.
HAMILTON: They're called descending devices. Some are just upside-down milk crates, while others are commercial products with a pressure-sensitive clamp that releases at a certain depth. What Lowe is trying to do now is make sure people who fish learn how to use these devices. We drop anchor and a dozen fishermen bait their hooks for rockfish. Nick Mackshanoff says he's been fishing a lot since he retired.
NICK MACKSHANOFF: If there's water, I fish. Fresh or salt, bathtubs, oceans, you name it, I fish.
HAMILTON: Like a lot of sport fishermen, Mackshanoff is concerned about overfishing and bycatch - fish that are caught unintentionally and die.
MACKSHANOFF: Something has to be done or 10, 20, 30 years from now there's not going to be any fish, period.
HAMILTON: So Mackshanoff has learned to gently release fish he's not going to eat. He's never used a descending device, but says he keeps hearing about them. And he's seen one on YouTube.
MACKSHANOFF: They were using this for Calico Bass. And it was minimal harm on fish and quick release back in the ocean again. I think it's kind of neat.
HAMILTON: As we're talking, another angler reels in a Bocaccio rockfish that's too small to keep. He hands the fish to Chris Lowe, who places it next to a small underwater camera and a descending device the size of a pocketknife.
LOWE: So what I'm doing now is I've clipped the fish on to the release device, turned on the camera, and now this fish, which clearly is showing signs of barotrauma, we're going to help it out by getting it down.
HAMILTON: Lowe uses a fishing rod to lower the fish, device and camera into the water. Later, he shows me the video.
LOWE: Here you can see the fish. Its eyes are going back into its head. You can see it kicking. It's trying to swim away, and then it releases.
HAMILTON: Of course, that's just one fish. So Tom Raftican of The Sportfishing Conservancy is working with Lowe to spread the word about the descending devices.
TOM RAFTICAN: There are well over 10 million marine recreational fishermen, and according to the National Marine Fisheries Service, each year we catch about 345 million fish.
HAMILTON: Raftican says sport fishermen release nearly two-thirds of the fish they reel in.
RAFTICAN: We've run workshops all around the country this past year, from Stellwagen Bank off Massachusetts down through the Carolinas, Florida and a couple in California, and actually one out in Lahaina, Hawaii, trying to get this information out.
HAMILTON: Raftican says it's an easy sell. Fishermen don't like to see a good fish wasted.
RAFTICAN: I love to fish, and I'd like to see my kids and grandkids out there fishing, too. And in order to do that, we've got to make sure that the resources are very healthy.
HAMILTON: Chris Lowe says that today's trip was a small step in that direction. Jon Hamilton, NPR News.
LOWE: There we go, a successful release - exactly what we want.