On re-introducing sturgeons to the river Rhine and the North Sea

Summary

This thesis investigates the feasibility of re-introducing the critically endangered European sturgeon (Acipenser sturio) to the river Rhine and the North Sea. The methods used are historical fisheries research, DNA identification of museum specimens, interviews with fishers and experimental releases and monitoring of young sturgeon tagged for telemetry. The return of this iconic flagship species, which can grow to over 4 metres in length and 400 kg in weight, would be a strong indicator of aquatic ecological recovery. The outcomes are moderately positive. Sturgeon find sufficient food in the North Sea and the Rhine has suitable spawning grounds for around 2500 female sturgeon. However, the thesis also highlights important bottlenecks such as by-catch at sea and problems of under-reporting, dams in the estuary, shipping in the river and the introduction of non-native sturgeon species. A shared long-term vision to address these human pressures is essential. The thesis concludes with six recommendations, including the establishment of a sturgeon breeding centre along the Rhine. For two sturgeon species: the European sturgeon and the Atlantic sturgeon (A. oxyrinchus), as the study provides evidence that both species were historically present, well into the twentieth century, in the river Rhine and the North Sea.