ANCHORAGE (AP) -- Video of salmon leaping into water spilling over a Ship Creek dam made for a rustic backdrop during an Anchorage TV weather forecast this summer, but the cute scene failed to charm Mike Roy.
Roy, a federal biologist, was one of a handful of people watching the news that night who realized those fish were stuck. They were banging fruitlessly against the concrete. They would die without spawning.
While only a smattering of Alaska streams have actual dams on them, hundreds, perhaps more than 1,000, are effectively dammed up nonetheless -- by culverts.
Culverts, ribbed metal tubes that funnel creeks beneath dirt roads, highways and train tracks, often pose big barriers for young and adult salmon, Roy said. Poorly built or crumbling culverts may choke off access to key spawning beds and feeding grounds in thousands of tiny tributaries, reducing the productivity of robust systems such as the Kenai, Susitna and Ninilchik rivers.
''I call it the death by a thousand cuts,'' said Roy, who manages fish habitat restoration programs in Alaska for the U.S. Fish and Wildlife Service.
Stream barriers are something for both sportfishermen and commercial fishermen to ponder, said Steve Albert, a state fisheries habitat biologist. ''Obviously, if a fish can't fully utilize what habitat there is available, then we're not getting as much productivity out of those stream systems.''
Federal funding from the National Marine Fisheries Service set off some initial work in 1998 on the Kenai Peninsula, but it was a 2000 U.S. Forest Service study highlighting serious problems with culverts in Southeast's Tongass National Forest that sparked broader interest.
That study found that about two-thirds of the Tongass logging road culverts in key salmon streams were hindering fish passage.
Researchers believe they will see similar results just about anywhere roads cross creeks.
''We have no idea how many culverts are problem culverts, whether they are partial barriers or total barriers to fish passage,'' said Albert, who began studying culverts on the Kenai Peninsula in 1998.
Culverts are everywhere, so common they go unnoticed, with more going in with each new subdivision.
''It's not glamorous, and it's not intuitive,'' Roy said.
''It takes us by surprise,'' said Jan Konigsburg, director of Trout Unlimited's biodiversity program in Alaska. ''It's right beneath our feet, and we don't even think about it.''
Culverts can threaten salmon and other fish in a variety of ways, Albert said. First, there is the problem of perched culverts, on which the outlet of the pipe is higher than the creek level. That can create insurmountable waterfalls, especially for fry, the juvenile salmon that need to feed in fresh water for months before heading out to sea.
Water speed also can thwart baby and adult fish. Water funneled through a culvert often is moving too fast for juveniles.
There are ways to fix those problems. Baffles built into culverts, or culverts partially filled with rocks to mimic the creek bed, can help slow the water, Albert said.
According to state law, construction within fish streams must allow free and efficient passage for fish. The way Albert describes it, a culvert shouldn't bar even the weakest swimming fish if the fish would otherwise make it upstream.
Fish advocates like Trout Unlimited's Konigsburg would like to see as many culverts as possible ripped out and replaced with bridges. But biologists like Albert and Roy said culverts aren't inherently bad if they are built right.
Last summer, Albert teamed up with the state Department of Transportation in a joint program to begin assessing the problem and come up with a reliable and quick way to grade culverts. With only so much highway money budgeted for repairs, the state will have to fix the worst fish bottlenecks first, he said.
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