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PRI's Environmental News Magazine

Estuaries 3: How Farming Impacts Salmon Territory

Air Date: Week of October 9, 1998

A new battle is emerging over salmon in the Pacific Northwest. Efforts to save certain species of the fish from extinction have focused largely on the damage caused by logging, dams, and urban development. But now, scientists are assessing agriculture's toll, in particular, the impact of farming on estuaries, the places where rivers flow into the sea. In the next installment of our series on America's estuaries, Living on Earth's Terry FitzPatrick explores efforts to reclaim land for the benefit of fish.

Transcript

CURWOOD: It's Living on Earth. I'm Steve Curwood. A new battle is emerging over salmon in the Pacific Northwest. Efforts to save certain species of the fish from extinction have focused largely on the damage caused by logging, dams, and urban development. But now, scientists are assessing agriculture's toll. In particular, the impact of farming on estuaries, the places where rivers flow into the sea. In the next installment of our series on America's estuaries, Living on Earth's Terry FitzPatrick explores efforts to reclaim land for the benefit of fish.

(A boat engine; traveling through water)

FITZ PATRICK: The Skagit River north of Seattle is one of the West's most important salmon streams. Fish begin their life in cold clear headwaters in the Cascade Mountains, and during their journey to the ocean pass through a wide muddy estuary on the shores of Puget Sound.

CAGNEY: I think we're still up here somewhere.

FITZ PATRICK: Biologist Pat Cagney of the US Army Corps of Engineers has come to this estuary because of the critical role it plays in salmon survival. At the point where the river currents converge with saltwater tides, salmon must accomplish one of nature's most difficult transformations.

CAGNEY: They need areas to change their physiology from a freshwater environment to a saltwater environment, and estuaries are where they need to do that.

(Boat engine continues)

FITZ PATRICK: The change happens at the cellular level, and ideally fish have weeks, even months, to complete the switch. An estuary's mix of fresh and salt water makes it a type of halfway house where salmon can also grow larger and stronger as they prepare for life in the ocean. However, for nearly a century, many fish have been unable to make this gradual transition, and instead have been swept out of the river into the sea before they're ready. That's because in the early 1900s, more than half the tide lands of the Skagit were diked and drained by farmers.

CAGNEY: This is what the West, how the West was built. The cities that grew up around here were built around that kind of a philosophy that we can live in the floodplain areas as long as we build our levees high, and all this will be improved land that has a commercial value.

FITZ PATRICK: Biologists consider the loss of estuary habitat to be one of the key reasons salmon are on the brink of extinction. Fish that make the fresh-to-saltwater transition too quickly aren't as likely to survive. Because they also miss out on the nurturing environs of an estuary, they wind up smaller and weaker, more likely to be eaten by predators. So, Mr. Cagney's team is planning to restore parts of the river to the way it looked before farmers arrived. They're surveying key sections of the Skagit estuary and will soon blow up parts of the dike.

(Boat comes to a halt; engine's cut. Sexauer unfolds a map)

SEXAUER: So, here we are.

FITZ PATRICK: Engineer Bruce Sexauer outlines the plan on a map. The area that's involved is no longer used by farmers.

SEXAUER: What we're going to do is we're going to create levee breaches down here in this area, in this area. And that's going to restore tidal inundation, daily tidal inundation to this entire area. The whole goal is just to restore it back to nature and let the currents and the conditions out here do all the restoration itself.

(A distant plane engine)

FITZ PATRICK: The Skagit River project is one of 2 dozen restoration efforts involving every major waterway in Puget Sound. Reclaiming habitat is one of the newest techniques in the struggle to rescue the Northwest's dwindling supply of wild salmon. The pilot project for this effort is proving that restoration does work.

(Surf and gulls)

FITZ PATRICK: This is Spencer Island at the mouth of the Snohomish River. The island's interior looks like a typical salt marsh with clusters of vegetation surrounded by mud flats. The water level rises and falls with the tide 12 feet every 6 hours.

(Splashing)

FITZ PATRICK: Biologist Curtis Tanner of the US Fish and Wildlife Service slogs through the mud to evaluate how the tides are affecting the kinds of plants that grow here.

(More splashing)

TANNER: The plants are really telling you what's happening to the environment. The plants are really sort of an indicator of the hydrology of how wet the place is, of the salinity, how salty it is. And the plants are certainly important by their own right, but they also provide the structure, the habitat that the fish and wildlife sources rely on.

FITZ PATRICK: There have been important changes in plant life since engineers breached the dikes that separate Spencer Island from the tides of Puget Sound. Invasive grasses and cattails that thrived on freshwater are giving way to salt-tolerant sedges and bullrush. They attract the kinds of insects that juvenile salmon consume.

TANNER: Insects are growing on the plants and falling in the water when the tide comes in. And salmon are sucking them up like little vacuum cleaners.

(Dripping water)

FITZ PATRICK: Tides are also carving a maze of waterways. Some are spacious channels. Others are rivulets just a few inches deep.

(To Tanner) Salmon will come up this?

TANNER: Absolutely, that's plenty of water for salmon. We're not talking about adult fish here returning to spawn. We're talking about juvenile fish that are an inch and a half to 2 inches long. They'll come in here during high tide when this area is underwater, do their thing, eat, feed, hang out, that used to be in an estuary, and they'll move back down into these channels as the tide goes out.

FITZ PATRICK: It's been 4 years since the dikes were breached at Spencer Island, and though fish are recolonizing the region, complete recovery may take a decade. Still, Mr. Tanner is convinced Nature can reclaim the marsh without more help from people. Scientists say restoring estuaries won't in itself bring salmon back from the brink. That will require a broader effort to limit fishing and protect upstream spawning grounds. There's even an experiment underway in one of the region's largest estuaries, Padilla Bay, to prevent eroded soil from washing off farm fields and damaging a sensitive marine reserve. These efforts are important because experts say salmon will never fully rebound without healthy estuaries, where fish can prepare for their perilous journey to the sea. For Living on Earth, I'm Terry FitzPatrick.

 

 

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