Abstract

The allis shad (Alosa alosa) is a type of migratory fish. While they typically live in the ocean, they travel to rivers during the spring months to lay eggs. Sadly, this journey can be deadly for many allis shad. This is because humans fish for them, they get blocked by dams, or the rivers are too polluted. And if these dangers weren’t enough, a new species called the European catfish likes to eat the allis shad. 

We wanted to find out if catfish truly are a threat to the already endangered allis shad. To do this, we monitored a part of the Garonne (a large river in France) where allis shad like to lay their eggs, and then we studied catfish hunting behavior.