Evaluating the carrying capacity of pink salmon in Sitka National Historical Park
January 2023 - December 2025
- National Park Service
Freshwater ecosystems supporting Pacific salmon exhibit natural and wide-ranging variability in the number of salmon they can support. In some areas, the carrying capacity is affected by hatchery-origin adults that stray from hatchery and instead return to nearby rivers and streams. The Indian River within Sitka National Historical Park once had returns of pink salmon numbering in the thousands. Following the construction of a nearby instructional hatchery that draws its water for egg incubation and juvenile rearing, many adults now "escape" the fishery and stray into the river, such that recent returns are two orders of magnitude higher. This project is a collaboration with scientists from the National Park Service (NPS), the Sitka Tribe of Alaska, the Sitka Sound Science Center, and Trout Unlimited. We will develop a model for evaluating a reasonable escapement goal for the river that also considers the effects of water withdrawals, which will help the NPS better manage pink salmon.