Data from: Early evidence for establishment of a Chinook salmon population in a restored watershed

As fish populations face compounding pressures under climate
change, highly modified rivers are receiving increasing research and
conservation attention as important sites for restoration. Across the
North Pacific Ocean, Chinook salmon (Oncorhynchus tshawytscha) have
experienced unprecedented declines and extirpations because of habitat
loss and fragmentation and climate variability. Here, we studied a rare
example of a novel salmon population developing in Putah Creek,
California, a dam-controlled stream flowing through an area of intensive
agriculture where salmon were unlikely to occur prior to the
rehabilitation of a more natural flow regime. We used otoliths from adult
Chinook salmon carcasses recovered from Putah Creek to determine river- or
hatchery-of-origin for five spawning year classes. Our results provide
evidence of successful salmon reproduction, outmigration survival, and
natal homing of individuals back to Putah Creek in recent years. Although
hatchery-origin fish that strayed to Putah Creek to spawn dominated
returns each year, this study documents life cycle completion required for
the potential development of a self-sustaining salmon population. This
study demonstrates that targeted restoration and flow rehabilitation
efforts can generate viable new salmon spawning habitat in dam-controlled
river systems, which could help mitigate habitat lost to dams and
developments. Further, successful anadromous life cycle completion can
occur in new spawning habitat within the first several generations, which
will help inform other efforts to restore or reintroduce salmon in altered
river systems.