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Salmon documented in streams on top of Pebble prospect

April 27th, 2011 | Margaret Bauman Print this article   Email this article  

A new fisheries research report documents the presence of wild salmon in streams on top of a major Southwest Alaska mine prospect and calls for further studies into potential impacts groundwater contamination could have on salmon populations.

"Combined stream survey data for 2008-2010 indicated salmon presence in 3 of every 4 headwater steams of less than 10 percent gradient draining to an anadromous river, including streams on top of the Pebble prospect, said authors Carol Ann Woody, a fisheries research scientist in Anchorage, and Sarah O'Neal, a biologist with the Wild Salmon Center in Portland, Ore.

"Rearing salmon were documented above dry stream reaches and in waters disconnected from rivers suggesting salmon access such sites during annual floods or via subsurface groundwater channels, the authors said.

The report, "Fish Surveys in Headwater Streams of the Nushagak and Kvichak River Drainages, Bristol Bay, Alaska 2008-2010, was prepared for The Nature Conservency. It was completed in December, and released in late April.

"We were the first to document salmon in streams on top of the ore deposit," Woody said. "We caught salmon in spring fed pools that weren't connected to any visible streams. "We found salmon in 3 of every 4 streams we surveyed, and fish important to subsistence, like Dolly Varden in 98 percent of the streams we looked at."

While the persistence of North American wild salmon in the Lower 48 and Canada is uncertain due primarily to habitat loss and degradation, millions of salmon continue to return every year to Alaska's Bristol Bay - some 42 million wild salmon in 2010 alone.

Commercial fishermen, in what was the 126th consecutive year of harvesting, brought in more than 30 million salmon.

Alaska Natives harvested over 100,000 salmon, preparing them for winter subsistence, as they have done for thousands of years. Sport anglers also came from around the world to fish the rivers of Bristol Bay for salmon, trout and char, Woody and O'Neal noted.

While Bristol Bay is the most valuable commercial salmon fishery in the nation, the contiguous mining claims now staked on the watershed divide of the bay's largest salmon producers - the Nushagak and Kvichak river drainages- pose both direct and indirect impacts on fish habitat and ecosystem function, they said.

Small headwater streams are often assumed not to be important salmon producing habitats in Alaska, although collectively they produce millions of salmon and determine water flow and chemistry of larger rivers, the authors said.

As illustrated by this and numerous other studies, headwaters comprise a significant proportion of essential spawning and rearing habitat for salmon and non-salmon species all of which are important to subsistence users in the region, they said.

The study also notes a lack of information on salmon use of ephemeral habitats and the critical role of groundwater , which the authors said warrants further investigation.

The Nature Conservancy, an international not-for-profit organization with a mission to preserve the biodiversity of the planet, began in the late 1990s to develop partnerships with local organizations to protect the long term viability of salmon resources in Bristol Bay. The partnership includes the Curyung Tribe of Dillingham, the Bristol Bay Native Association and the Nushagak-Mulchatna Watershed Council.

While development of the Pebble prospect is uncertain, the Nature Conservancy and its partners, nevertheless, determined the possibility of a large mining effort in the watersheds of Bristol Bay's largest rivers raised a significant threat to wild salmon habitat, said Tim Troll, Southwest Alaska program director for the Conservancy, in a preface to the report.

Troll also notes that the Anadromous Fish Act, the state's statutory protection for freshwater habitats of fish in Alaska, requires the state Department of Fish and Game to specify various state waterways that are important to spawning, rearing or migration of anadromous fishes. When one of these waterways is included in the state's Catalog of Waters Important for the Spawning, Rearing or Migration of Anadromous Fishes, nobody may use, divert, obstruct, pollute or change the natural flow of that water body without a permit from the Alaska Department of Fish and Game.

The results of the surveys in 2008, 2009 and 20120 strongly suggest that unambiguous observation of salmon will be made in almost any headwater stream within the Pebble prospect and nearby mining claims, Troll said.

Accordingly, Troll said, the Conservancy makes two recommendations.

The first is that exhaustive fish distribution surveys should be undertaken by the state to document all anadromous waters within the Pebble prospect and adjacent leased areas that may become economically viable to develop if the mine is permitted.

The second is that fish distribution surveys should also include any stream that will be crossed by an access road or potentially affected by any other projected related infrastructure, he said.


Margaret Bauman can be reached at, or by phone at 907-348-2438

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