Genetic data confirm the presence of juvenile Alosa alosa in the estuary of the River Tamar

Abstract

Within the UK, allis shad (Alosa alosa) are classified as Critically Endangered and are known to breed in only a single river, the Tamar. Despite evidence of spawning within the lower freshwater reaches of the river and at the tidal limit within the estuary, juvenile allis shad have never been found. Genetic analysis, based on mitochondrial DNA haplotype and nuclear Polymerase Chain Reaction - Restriction Fragment Length Polymorphism (PCR-RFLP) data, confirmed that juvenile shad found within the lower Tamar estuary in autumn 2022 were A. alosa.