Building Bridges to Restore Connectivity: Penobscot Nation and NOAA Fisheries Improve Atlantic Salmon Resilience

The Penobscot Nationconserves and recovers endangered Atlantic salmonand facilitates their return to Tribal lands. The Nation completes these conservation efforts with help from the NOAA Fisheries' Species Recovery Grants to TribesProgram. Their latest project focuses on restoring aquatic habitat connectivity to promote the species' resilience in the face of climate change.

The Importance of the Penobscot River Watershed

For thousands of years, the Penobscot River has served as a highway for the Penobscot people, who live along its banks. To this day, the river provides food for the community, is central to their culture, and is considered a Tribal citizen. "We hunt and fish and gather there, and we respect the river as our relative who provides sustenance to us," said Chuck Loring, a member of the Penobscot Nation and the Director of the Tribe's Department of Natural Resources. The Penobscot River is now one of the last places in the United States where endangered Atlantic salmonlive. The species is important to the Nation.

Atlantic salmon once migrated inland by the hundreds of thousands to rivers in the northeastern United States. Beginning in the 1800s, dam construction along the Penobscot River severely reduced fish passage. Later, undersized culverts prevented fish passage throughout tributaries including headwater streams. Atlantic salmon face many threats in the northeast United States due to dams, including warming waters, high predation from species such as smallmouth bass, and modified habitats.

Free-flowing and connected rivers are vital to anadromous fishsuch as Atlantic salmon, providing uninterrupted migration between freshwater and the ocean. This connectivity ensures that the salmon can hatch in the river, mature in the ocean, and return to spawn in the waters in which they were born. Sea-run fishalso play an important role in the ecosystem by carrying nutrients and energy from the ocean to the rivers. For example, when they die, Atlantic salmon bodies provide nutrients such as nitrogen and phosphorus to the river system. Maintaining connected rivers is essential not only for the survival of Atlantic salmon but also for the health and productivity of the ecosystem.

Dams Block Salmon from Reaching Habitat

Dams and barriers can block, delay, and kill Atlantic salmon and destroy freshwater spawning and nursery habitats, unless they are removed or equipped with adequate fish passage. Today, more than 400 dams along rivers and streams block or impair migration corridors and alter habitat conditions that impede both the survival and recovery of Atlantic salmon. Salmon populations have greatly diminished, with around 1,500 fish returning to Maine rivers in 2023. The West Branch of the Penobscot River was one of the most important, abundant, and historical salmon habitats. However, today it largely remains inaccessible to salmon because of numerous dams that lack fish passage; dams are one of the principal causes of their decline. The Penobscot Nation's efforts aim to restore these vital "highways" for salmon and other sea-run fish to thrive.

Ongoing Efforts to Restore Salmon Habitat

Culverts can block fish passage or impair migration and destroy habitat by changing streamflows and altering stream channels. However, bridges support more natural stream features, such as water depth and flow speed. This enables fish passage, improves Atlantic salmon habitat, and provides protection for Atlantic salmon eggs. Under the Species Recovery Grants to Tribes program, the Penobscot Nation has successfully replaced culverts with bridges at two road-stream crossings in the Mattamiscontis Stream. Support from the program has allowed the Nation and project partners to complete another 16 connectivity projects since 2011. Together, these projects are helping to reconnect the upper reaches of Mattamiscontis Stream to the Penobscot River.

The Penobscot Nation has also increased their participation in the Atlantic Salmon Collaborative Management Strategy. The Strategy establishes a platform for effective communication and collaboration between multiple partners. The Nation's voice is important in this process. Their involvement facilitates the implementation of the 2019 Final Recovery Plan for the Gulf of Maine Distinct Population Segment of Atlantic Salmon. This work is critical in supporting ecosystem-wide restoration for the recovery of Atlantic salmon and requires the collective efforts of many partners.

The Nation's participation in the Strategy provides an opportunity for the integration of Traditional Ecological Knowledge (also known as Indigenous Knowledge). This allows the Nation to voice their cultural perspectives, while advocating for essential dam fish passage structures and operational practices. Traditional Ecological Knowledge offers a profound understanding of local environmental changes and ecological patterns that modern science alone might not fully capture.

As Dan McCaw, the Fisheries Program Manager for the Penobscot Nation, emphasizes, "The Tribal people stewarded these rivers since time immemorial and had some of the most robust fish runs in the world. They continue to manage forests very conservatively. There's a huge benefit of bringing in Traditional Ecological Knowledge and weaving it with modern science in a very respectful way. This integration is not always simple or easy, but it ensures that the Tribe has an important voice in the recovery effort."

In 2023, the Nation's (and their partners) efforts led to the highest return of Atlantic salmon to the Penobscot River in more than a decade. These efforts also have benefits to other sea-run species. Improved fish passage on the Mattamiscontis Stream enabled river herring(alewives and blueback herring) to reach spawning lakes that could support nearly 800,000 fish. River herring are prey for many birds and other fish, such as bald eagles and striped bass, so their resurgence may serve to buffer juvenile Atlantic salmon from predators.

NOAA Fisheries further supports the Penobscot Nations' work through the Bipartisan Infrastructure Law and Inflation Reduction Act. This funding supported construction of fish passage projects on Birch Stream, a tributary of the Penobscot River. These projects will improve access to additional cold-water habitatfor Atlantic salmon. The Bipartisan Infrastructure Law funding will also support the construction of a hiking trail along Sam Ayers Stream on Tribal lands later this year. The trail will highlight recent and future restoration projects through informational kiosks. The Penobscot Nation is hopeful that increasing opportunities for Tribal and non-tribal members to see and access the restored lands and kiosks will continue public support and engagement for important ongoing and future restoration projects.

Building Resilience for Climate Change

Climate change exacerbates the urgency of the Nation's restoration work to increase Atlantic salmon's resilience. Restoring free-flowing rivers and streams aligns with traditional practices and enhances ecosystem and infrastructure resiliencein the face of climate change. Projected increases in precipitation and more frequent intense storms in the Northeast United States pose significant risks. For example, flooding in December 2023highlighted the growing threats associated with these changes in Maine. These road-stream crossing projects help to mitigate flood risks by supporting wider ranges of water flows and improving fish passage. By integrating Traditional Ecological Knowledge into the management of the river system, the Penobscot Nation is better prepared to address these climate challenges. As climate change intensifies, these proactive restoration efforts are crucial for sustaining Atlantic salmon populations and maintaining the health of the ecosystem while protecting critical infrastructure.

Despite significant progress, much work remains to recover Atlantic salmon populations in Maine. With support from NOAA's Species Recovery Grants to Tribes Program, the Penobscot Nation continues its restoration efforts for Atlantic salmon populations in the Penobscot River watershed. These efforts align with NOAA Fisheries' broader vision to restore habitats and reopen migratory routes, ensuring fish access to healthy environments.

Chuck Loring highlights the Penobscot Nation's commitment to restoration: "The Tribe takes a seven-generation approach to conservation. That's our motivation to work hard now. I might not be able to see the results, but my descendants will."

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