Allis shad are rare in the UK and populations are declining in Europe. The only confirmed spawning sites for allis shad are in the Tamar Estuary. This site is also an important area for spawning populations of smelt. The UK smelt population is depleted and protecting estuaries used by the species is important because they can become locally extinct from isolated estuaries and will not return. The main threats to allis shad and smelt include pollution, over-exploitation, habitat destruction/degradation and barriers to migration. Natural England is responsible for reporting to government on the condition of these species. Prior to this study allis shad and smelt populations were poorly researched within the site.
This project provided the first targeted evidence of condition of allis shad and cucumber smelt for the site. In summary, the status of the Tamar allis shad population is uncertain but there are several observations that give cause for concern, namely the sharp downturn in the number of allis shad seen migrating upstream via Gunnislake Fish Trap since 2011 and the apparent use of just one spawning site in the upper Tamar Estuary. The status of the Tamar smelt population is less clear as this is the first year of survey for the species and no spawning site was located, however the presence of a range of age classes suggests that in previous years spawning in the site was successful.