Salmon return to lay eggs in historic habitat after Klamath River dam removal

Dam removal, habitat, and salmon return

• Many celebrate the rapid return of salmon to upper Klamath tributaries as proof that removing dams quickly restores access to historic habitat.
• Several note this is the first anadromous return above certain dams in over a century, citing state biologists.
• Others initially claimed salmon “never left,” but are corrected: salmon spawned below the dams; upper basin was fully blocked.
• Commenters stress that dam removal is more than obstacle removal: it restores cooler flows, gravel beds, and reduces harmful algae and siltation.

Fish ladders, weirs, and hatcheries

• Strong disagreement over effectiveness of ladders and weirs: some call them “fish killers” that are poor substitutes for a free river; others say well‑designed ladders can pass nearly all fish.
• Clarification that some Klamath dams lacked adequate ladders, hence the century‑long barrier.
• Hatcheries are debated: some see them as efficient production tools; others as a poor simulacrum that harms genetics and doesn’t fully replace natural spawning.
• “Trucking” fish around dams and high‑tech “fish cannons” are mentioned as partial, often inefficient fixes.

How salmon navigate and “memory” debate

• Many push back on “genetic memory” language. Consensus: behavior is driven by innate tendencies plus individual learning.
• Proposed mechanisms: following freshwater flow and gradients; highly acute sense of smell for natal stream “scent”; possible geomagnetic cues at sea.
• Important role of “strays”: a small fraction of salmon naturally colonize new or re‑opened habitat; hundreds of fish in this story likely fit that pattern.
• Epigenetics is mentioned but commenters warn it is often misused in pop science.
• A long sub‑thread debates instinct vs learned behavior (e.g., human babies walking, foals, beavers building dams), with some invoking mysticism and “life force,” which others strongly label pseudoscience.

Energy, dams, and policy trade‑offs

• Some argue hydropower is crucial green energy and criticize dam removal as anti‑environmental.
• Others counter these particular dams are old, silted, marginal for power and flood control, and costly to maintain versus remove.
• Broader discussion emphasizes that science informs impacts, but choices are value‑laden trade‑offs (fish and tribal rights vs. local reservoir users, recreation, small hydropower).

Broader ecological and behavioral notes

• Examples from Europe and elsewhere: salmon and other wildlife rapidly return when barriers and pollution are reduced.
• Tire‑derived chemical (6PPD‑quinone) in road runoff is cited as a major killer of salmon in urban streams.