De elft: succesvolle herintroductie van een vergeten riviertrekvis

Allis shad: succesful re-introduction of a forgotten migrating fish The allis shad was an important migratory fish in Europe. It is a diadrome fish species. They spawn and grow up in fresh water and become an adult fi sh in salt water.Nowadays, the allis shad is threatened in whole Europe. Due to river channelling, pollution and fi sheries, the catches in the Rhine dropped from 50,000-100,000 fish per year in the period 1880-1900, to less than 10,000 around 1900-1910 and to almost zero at World War 1. The maximum catch was 300,000 fish in a year in Holland.In 2008, the project ‘European Life Project on the Re-Introduction of Allis Shad to the River Rhine’ was launched, that fi rst studied the feasibility of a reintroduction. Close to 13 million larvae were introduced to the Rhine. As a result, since 2014 a growing number of adult allis shads are found, visiting their birth grounds in the Rhine, to reproduce. In 2012 a new EU Life+ project started with the title ‘Conservation and restoration of the Allis shad in the Rhine and Gironde watersheds’, with emphasis on the recovery of the Allis shad stock in both rivers. In the Gironne-Gardonne-Dordogne system, the only viable population left in Europe, decreased from more than 300,000-500,000 fish/year before 2000 to an alarming low level of a few thousand fishes