Work

Eco‐Evolutionary Dynamics of Anadromous Alewife Restoration in a Whole‐Ecosystem Experiment

Year: 2026

Type: article

Abstract: ) to a lake occupied by a well-established landlocked population isolated ca. 350 years ago. The restoration of Rogers Lake involved the construction of fishways on all downstream dams and the annual stocking of anadromous adults. Throughout the restoration project, we quantified juvenile recruitment, abundance, and growth, as well as hybridization and introgression with the landlocked population. Restoration led to the annual production of anadromous juveniles and the natural return of anadromous adults. During the decade of restoration, > 27,000 anadromous adults ascended the fishway, with ~78% identified as offspring of stocked parents. Juvenile anadromous abundance fluctuated annually but never exceeded 8% of the total juvenile composition. Anadromous juveniles in Rogers Lake grew faster than those in nearby Bride Lake, the source of the stocked anadromous adults, and matched landlocked and hybrid growth rates. Parentage analyses revealed that stocking date influenced reproductive success, age-of-return, and day-of return. Hybrid juveniles appeared early in the restoration and increased in abundance. Hybrids exhibited both life histories, with the majority remaining in the lake as freshwater residents, but several returning as mature anadromous adults. Landlocked juvenile abundance declined, suggesting ongoing demographic shifts through the restoration. Overall, restoration efforts reestablished the anadromous life history in the lake but also led to hybridization between forms. These results provide an example of how evolutionary processes can shape the outcome of restoration efforts.

Source: Evolutionary Applications

DOI: 10.1111/eva.70350