Feeding of hatchery-reared juvenile Atlantic sturgeon, Acipenser oxyrinchus Mitchill, released into the Drwęca River

Abstract

Atlantic sturgeon, Acipenser oxyrinchus Mitchill was once one of the largest European freshwater fish, and it was common in the Vistula River drainage. Since 2006, juvenile Atlantic sturgeon obtained by artificially reproducing wild spawners caught in the St. John River in Canada have been stocked into several rivers in Poland. The current study to assess the feeding of Atlantic sturgeon in the Drweca River in Poland is part of a larger project to restore the species to this region. Hatchery-reared eleven-month-old Atlantic sturgeon were recaptured 2 to 10 days after their release into the river. This study provides the first data on the diet of A. oxyrinchus in the fresh waters of Europe. In June 2008, the stomach contents of the juvenile Atlantic sturgeon that had been recaptured were collected using gastric lavage. Of the 70 sturgeon the Drweca River which were subjected to gastric lavage, 67% of them had empty stomachs. The diet of juvenile Atlantic sturgeon consisted of nine taxa of prey. Primarily, sturgeon eat small, soft-bodied larval Oligochaetae and Chironomidae.