The restoration of depleted native fish stocks and the recovery of threatened and endangered fishes are among the highest priorities for fisheries management in the National Park System. Restoration of native fish populations and communities may involve the control or eradication of nonnative species that have contributed to depletion through predation, hybridization, or competition for limiting resources. Activities to achieve restoration may also include reintroduction to unoccupied habitats, barrier removal or modification, and implementation of special fishing regulations.
Restoring native fish populations is important both because of their value as a recreational resource for visitors and because of the functions they serve in park ecosystems. Many species of terrestrial and aquatic wildlife rely on fish as a food source. Anadromous fish, which grow and mature in the ocean before returning to spawn in freshwater, are critical to the productivity of many aquatic, riparian, and adjacent terrestrial ecosystems.
Many NPS units protect watersheds and aquatic habitats that serve as refuges for healthy populations of native fish species that have declined elsewhere within their ranges. This situation is most typical of parks that are isolated and/or located near the headwaters of large watersheds. In such areas, the protection of habitat is a top priority.
In other areas, habitats have been degraded by activities inside or outside of the park, and the focus is on restoration. Because the factors affecting aquatic habitat often transcend NPS boundaries, habitat restoration is frequently conducted in partnership with states, tribes, other federal agencies, and private entities. Aquatic habitat restoration projects have included improving stream access for salmon and steelhead; recreating cover and woody debris in streams; reestablishing natural stream bed channels and meanders; dam removal, culvert replacements, and stream bank erosion control; and the removal and control of invasive riparian vegetation such as tamarisk.