During 2023, we have been conducting surveys of potential shad spawning and juvenile habitat, along with identifying possible barriers to their migration.

This project brought together various partners such as Natural England, the Environment Agency and numerous angling groups within the Taw and Torridge catchments.

A total of 32.88km of the Torridge, Taw and Mole have been surveyed.

There are two populations of shad in the UK, the allis (Alosa alosa) and Twaite (Alosa fallax), but there is limited information on allis shad distribution nationally. The only known spawning population of allis shad in England is in the River Tamar.

A number of shad were observed to migrate into the Taw catchment in late spring and early summer, and a dead specimen found by an angler was donated to us for further investigation.

The most definitive feature distinguishing between the two species is the difference in gill structure, most notably the gill rakers. These differ in structure and count. Therefore, full identification is a somewhat invasive procedure.

Following dissection and examination of distinguishing features such as fork length and gonads, the fish was confirmed as a female allis shad.

The presence of eggs allowed the determination of gender. However, the same presence means that we are unable to guarantee whether this fish has spawned.

Although allis shad within the River Taw has now been confirmed, whether these fish are part of a viable spawning population is still to be discovered.

Further work to verify this will be conducted, including egg surveys and eDNA sampling.

With the IUCN’s latest Red List publication showing that 25% of the world’s freshwater fish species are at risk of extinction due to water pollution, dams, overfishing and climate change, it is important that we determine species distributions. This helps to make conservation decision such as improving migration to spawning habitats within river catchments.

You can support our fish and river monitoring work by making a donation at wrt.org.uk/support

You can also purchase a copy of the children’s book Allis the Shad Who Wouldn’t Give Up at wrt.org.uk/product/allis-the-shad

Featured image: Illustration by Sarah Gledhill from the Allis the Shad Who Wouldn’t Give Up book.