T77 Watersheds

Jan 30, 2015
Uploaded by Audubon Alaska
The Top 77, also known as the “Salmon Forest” Proposal, designates key watersheds in Southeast Alaska for permanent protection to safeguard the most important habitat across the region. The proposal is based on a scientific assessment of Southeast Alaska’s Coastal Forests and Mountains Ecoregion (Schoen and Dovichin 2007). The assessment resulted in a habitat ranking system for six salmonid species as well as other values. Top watersheds were identified in each of the 22 biogeographic provinces in Southeast Alaska (developed by the U.S. Forest Service), based on combined values for these six anadromous fish species plus related habitat quality indicators such as old-growth forest, bear and deer habitat, and estuaries.

Salmon were selected as focal species for forest management because spawning and rearing salmon are widely distributed in streams and rivers throughout Southeast Alaska and play a fundamental role in the ecology of coastal, freshwater, and terrestrial systems. Salmon are considered to be keystone species because they transfer marine-derived nutrients into the terrestrial and freshwater ecosystems and many terrestrial and freshwater species and ecological processes are inextricably connected to salmon (Wilson and Halupka 1995).Top watersheds were assessed for each biogeographic province to account for the unique island biogeography of different areas of the Tongass. The Top 77 are a dispersed network of sites identified at the whole watershed scale, employing both a “single large” and “several small” reserve design at the province or ecoregion scale, respectively. This land management strategy is analogous to preserving an ecological investment portfolio (Schindler et al. 2010).

The Top 77 proposal includes all of the #1 watersheds within each biogeographic province, based on values for all six fish species and related habitat conservation targets. The proposal will permanently protect top watersheds in Southeast Alaska. Included in the Top 77 are the #1 ranking watershed in each biogeographic province for the six individual fish species assessed, as well as the highest ranking watersheds for all salmonids combined. Species included: 

  • King (chinook)salmon
  • Red (sockeye)salmon
  • Silver (coho) salmon
  • Pink (humpy) salmon
  • Chum (dog) salmon
  • Steelhead trout

In addition to including valuable fish habitat, the proposal is supplemented with watersheds that capture other biological values to ensure the region will sustain a viable ecosystem. The Top 77 captures the #1 ranking watershed in each biogeographic province for the following ecosystem components which are highly correlated with healthy salmon habitat:
  • Estuaries (highly important anadromous fish habitat)
  • Riparian large-tree old growth (nutrient exchange, large woody debris, cold water refuge, erosion stability)
  • Black and brown bear summer habitat (correlated with salmon concentration areas)
  • Sitka black-tailed deer wintering habitat (indicative of healthy upland forest at the watershed scale)
  • Marbled murrelet nesting habitat (an ecological link between old-growth forest and the marine ecosystem)

All #1 watersheds in Southeast Alaska were included in the proposal, except: those already protected, in non-federal ownership, actively managed for other values (such as urban recreation, experimental forest, or active timber sale), or lacking public support (for example, the strong land owner opposition to protecting the Taku, which is the top salmon watershed in all of Southeast Alaska). In addition to the #1 watersheds, the proposal includes several carefully chosen individual watersheds deemed important through additional review by scientists and fishers. Additional watersheds met one or more of the following criteria:

  • Based on all salmonid values combined, was within the top 10% of watersheds in Southeast Alaska (without the province filter)
  • Based on all (salmonid and other) habitat correlates combined, was within the top 10% of watersheds in Southeast Alaska (without the province filter)
  • Was within the top 5 watersheds for a biogeographic province
  • Was a Tier 1 watershed based on ecological optimization modeling as described by Albert and Schoen (2007). Tier 1 watersheds are within the top 25% of each biogeographic province, based on an evaluation of the smallest footprint to achieve the highest value for the combination of all salmonid and other habitat correlates combined.

Based on several years of rigorous data collection, scientific analysis, and modeling, and mixed with local fisherman knowledge of the highest productivity areas, the Top 77 captures the most important places in Southeast Alaska’s Tongass National Forest to ensure the long-term existence and health of the Southeast Alaska ecosystem and salmon fishery.
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Audubon Alaska, The Nature Conservancy, Trout Unlimited
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Audubon Alaska

Audubon Alaska's mission is to conserve the spectacular natural ecosystems of the Great Land, focusing on birds, other wildlife, and their habitats, for the benefit and enjoyment of current and future generations of all Americans. We use science to identify conservation priorities and support...