Fish Passes: Forest Service Enhancement Boosts Tongass Salmon Production

The value of salmon fisheries for ecosystems, industry, personal, sport, and traditional use is unquantifiable in Southeast Alaska. The lakes and streams of the Tongass National Forest contribute the vast majority of this pivotal resource- producing 79% of the annual commercial harvest, about 50 million salmon each year. In its efforts to manage the Tongass for salmon, the US Forest Service invests in a variety of projects that ensure continued high productivity of fisheries and watershed resources. 'Fish Pass' installation has proven to be a powerful and effective option- an integral component of the Forest Service's tool-kit to boost salmon production from Tongass systems.

'Fish passes' are constructed to bridge waterfalls that historically restrained salmon from accessing quality upstream spawning and rearing habitat. To protect the natural integrity of this lush national forest, the Forest Service adheres to a 'minimalistic yet effective' construction policy- minimizing environmental alteration while maximizing fish access. The vast majority of watersheds in the Tongass remain unaltered with only the most strategic and promising barriers selected for fish pass installation. Passes take many forms varying from nonstructural 'step pools' blasted out of natural bedrock to the Alaskan Steeppass 'fish ladder' that harnesses water current to push exhausted salmon to the top of barrier falls. Whatever the type, Fish Passes follow the same basic principle- allow more fish access to more area.

Increased spawning and rearing habitat translates into less competition for space and nutrients with more salmon surviving to adulthood. Following this basic principle, the Forest Service has successfully improved production of Tongass fish. Fish Passes have opened access of 443 stream miles and 4,931 lake acres to spawning and rearing steelhead and salmon. Exact fish counts produced by increased area are difficult to calculate and are estimated by projecting the average number of fish produced given particular habitat quality by the amount of increased area. Conservative estimates suggest an average of 86,855 coho and sockeye and 227,500 pink and chum salmon adults added each year as a direct result of this increased area made available by fish passes. At the current rate of a dollar and ten cents per pound for coho and sockeye and forty two cents a pound for pink and chums, fish pass produced salmon add an impressive estimated $8,598,930- over eight and a half million dollars- to Southeast Alaskan economy over a ten year period.

Unfortunately, like everything man-made, structural fish passes require maintenance to remain effective. There are approximately fifty fish passes across the Tongass- about fifteen operating in the Sitka Ranger District alone. The majority being between 20-30 years old, structural fish passes are reaching the point in their lifetime where they require considerable work. Managing this forest and recognizing that salmon are one of the most important outputs that benefit both humans and the overall ecosystem means continued investment in projects like fish pass construction and maintenance.

We are fortunate to have learned from mistakes made across other regions of the world where wild salmon populations were pushed to extinction. We are even more fortunate to boast a talented fisheries staff and a holistic fisheries and watershed program that manage and protect the future of this valuable resource. Fish passes are one of the significant activities within this program that ensure wild Alaskan salmon continue to sustain the communities of Southeast Alaska and that the Tongass continues to rear the salmon that are base of the last remaining sustainable fisheries in the world.

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