STEVE INSKEEP, host:
It's MORNING EDITION, from NPR News. Good morning. I'm Steve Inskeep.
Along the East coast, the striped bass is among the most coveted of fish. They're big and full-bodied, with dark stripes along the sides, and they're delicious. In the 1980s, the stripers were in deep trouble. Wildlife managers said they were overfished, and they laid down strict catch limits. The population recovered, fishing resumed in what's considered one of conservation's great success stories - until now. Catches are down again.
As NPR's Christopher Joyce reports, some biologists say the problem is not overfishing this time. It's the weather.
CHRISTOPHER JOYCE: Brad Burns started fishing for striped bass in 1960. Last week, I caught him by phone as he was running a booth for his group, Stripers Forever, at a fly-fishing show in New Jersey. He says his members have been singing the blues about stripers.
Mr. BRAD BURNS (Stripers Forever): What we hear from people that go striped bass fishing, the general trend very decidedly is down.
JOYCE: Stripers live in the ocean, as well as in estuaries and some rivers. Burns says members have been reporting fewer fish for the past five years. As for the cause...
Mr. BURNS: Well, I don't know, and I don't know that anybody does.
JOYCE: But Bob Wood thinks he might. Wood's a biologist at the National Oceanic and Atmospheric Administration. He studies his fish in a boxy little building on the Maryland shore of the Chesapeake Bay.
Dr. BOB WOOD (National Oceanic and Atmospheric Administration): Come on in. And what we have here is a way to run controlled experiments on nutrition and disease.
JOYCE: Here, scientists keep vats full of striped bass and white perch, two species that spawn in the Bay. This is where Wood's team tries to figure out why striper numbers go up and go down. They thought they had the 1980s crash figured out.
Dr. WOOD: The striped bass crashed because of overfishing, and then it recovered because we closed the fishery.
JOYCE: But now Wood has new idea that's just taking shape.
Dr. WOOD: This research, at first glance, seems to call that into question. But it's not that easy.
JOYCE: This novel idea focuses not so much on fish, but on the weather, and especially the Atlantic Multidecadal Oscillation, or the AMO. The AMO is a mash-up of wind and ocean currents, a flip-flop that happens every 35 years or so in the North Atlantic.
Dr. WOOD: Circulation changes in a way that warms the entire basin. And you can imagine if you warm the entire North Atlantic basin, you're changing the weather because the air and circulation patterns above the ocean are then affected.
JOYCE: Ed Martino is a fisheries scientist who works with Wood at NOAA. He says when that AMO shift happens, it affects the local weather along the Atlantic Coast.
Dr. ED MARTINO (Fishery Scientist, National Oceanic and Atmospheric Administration): You're talking about differences in temperature and precipitation, and therefore river flow or salinity, ultimately all affecting the base of the food chain. It's the way that the climate affects the microscopic plankton.
JOYCE: Plankton - little tiny plants and animals in the water. That's what young stripers eat. Here's how they think the AMO is messing with fish food. When it's in a warm phase, springtime along the East coast actually tends to be wet and cool - more rain, more water, more food. In the years following that phase, striper numbers tend to go up.
Then the AMO flips - drier springs, less rain, less food. After a lag, it looks like striper numbers start to decline. Wood says the past 100 years of fishing records show that very trend, which brings us to the present crash in stripers.
Dr. WOOD: It hasn't been so good in the last, say, five years. And it just so happens, this is also the time when the Atlantic Multidecadal Oscillation seems to be switching phase.
JOYCE: Into a bad-for-stripers phase. Wood suspects it was also a down cycle that caused the striper crash in the 1980s. When that cycle ended, stripers recovered - not just due to the fishing limits, but because the fish liked the weather better.
Janet Nye studies fish stocks for the federal Environmental Protection Agency. She thinks this research could help fisheries managers.
Dr. JANET NYE (Environmental Protection Agency): We would be able to say, OK, for the next 35 years or so, we're pretty certain that the AMO is going to be more positive or warm. And we'd be able to say, these are the fish that respond favorably to that. You might be able to fish those more.
JOYCE: Or in a down cycle, says Bob Wood, fish less.
Dr. WOOD: If we know that there is this cycle coming up, a trend that we are beginning to enter, we can keep that in our heads as we set limits.
JOYCE: If Wood's research is correct, it may take tougher catch limits to bring striper numbers back up again.
Christopher Joyce, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.