Abstract
This study aims to reconstruct the historical spatiotemporal distribution of the anadromous sturgeons, Acipenser sturio and A. oxyrinchus, in NW-Europe (especially in the Rhine, Meuse, Scheldt, and Ems rivers, and in the North Sea), in light of evaluating the possibilities for their reintroduction. It is based on fisheries data from the 14th–twentieth century, consisting of > 5000 records of sturgeon landings and sales (c. 40,000 specimens) from the Netherlands, Belgium, Germany, Luxemburg, France and Switzerland. Most data originate from fisheries in the Rhine-Meuse delta (c. 28,000 specimens, 98% of the Rhine catches). Further upstream, far fewer sturgeons (c. 600 specimens) were reported from the Rhine’s mainstem and its principal tributaries, Mosel, Neckar and Main. Smaller tributaries and the Ems, Meuse, and Scheldt rivers seldom yielded sturgeons. This spatial pattern can be related to the species’ preference for large-river habitat, combined with fisheries activities that were most intensive in the delta areas. Sturgeon catches began to dwindle in the late nineteenth century, at a time when river engineering first strongly affected the sturgeon’s reproductive habitats in the Lower Rhine and delta areas. Also from then onwards, North Sea fishery pressure increased, as trawlers switched from sail to steam-powered propulsion. These sea fisheries harvested all age-classes of sturgeons year-round, including populations from other European rivers. The outcomes strongly suggest that NW-European sturgeon populations were initially impacted by intensive river fisheries, but especially by destruction of reproductive habitat, due to river regulation, and an intensified North Sea fishery, ultimately resulting in total population collapse.
Highlights
Sturgeons only occur in the Northern Hemisphere (Billard and Lecointre 2000)
This study aims to reconstruct the historical spatiotemporal distribution of sturgeons in the river Rhine and in the adjacent Ems, Meuse and Scheldt rivers (Fig. 1)
Its drainage basin covers 185,260 k m2, along a total length of 1230 km, with an average discharge of about 2200 m3/s (Uehlinger et al 2009) (Fig. 1). It flows to the north, from its origin in the Alps in Switzerland, through Germany, France and Luxemburg, to the lowlands in the Netherlands where it drains into the North Sea
Summary
Sturgeons (order Acipenseriformes; sturgeons and paddlefish) only occur in the Northern Hemisphere (Billard and Lecointre 2000). Most sturgeons are long-lived, large-bodied, late-maturing fish that undertake long-distance anadromous migrations through marine, estuarine and riverine habitats (Bemis and Kynard 1997). Due to these life history characteristics and their anadromous nature, sturgeon populations are affected by (marine) overfishing and river engineering. According to the IUCN Red Data List, at present 85% of all Acipenseriformes are endangered, making it the most threatened order of vertebrates in the world This conservation status is a wake-up call to restore their populations, migration routes, and core habitats in their natal rivers and estuaries (for spawning, nursery, and salt/freshwater acclimatisation)
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