A Glimpse of a Better Future for the Danube's Flagship Species - First Return of Stocked Sturgeons into the River

Abstract

In the present study, 4 specimens of sturgeons from stocking-programmes was recorded,out of a total 34 Danube River upstream-migrants towards their spawning grounds. The catches were recorded over a period of 42 days of scientific fishing on an area of 50.23% of the Danube River width. Three out of four native species were recorded during scientific fishing: 4 Huso huso, 27 A. stellatus and 3 A. gueldenstaedtii. CWT reading showed that all four individuals from stocking- programmes were males, three A. gueldenstaedtii and one A. stellatus. The captured specimens represent not only the first registered individuals returning to their home river but also a real chance for restoration of the A. gueldenstaedtii population into the Danube River. To the best of our knowledge, this is the first time in the world when the return of stocked sturgeons to their home river is reported. Consequently, identifying the main factors which have enabled this is crucial and represents a real breakthrough in sturgeon conservation. Our data suggest that the stocking program success is more likely dependent on the presence of wild individuals from whom stocked individuals can “learn” the way to the spawning grounds, than on the intrinsic traits of the stocking programme. Therefore, there is a need for additional studies to further understand if this return is an isolated case or it is the beginning of a better future for Danube River sturgeon populations. More information is also needed to assess the contribution of the stocked individuals to spawning events.

Keywords

• stocked sturgeons
• supportive stocking
• return to the river
• Danube River