Why did the sturgeon disappear?
‘This large fish is relatively easy to catch with traditional fishing gear. Ever since the Middle Ages the sturgeon has been heavily under threat from the fishing industry. In addition, many barriers have been erected in the Rhine, such as weirs and dams. River pollution was never an issue for the sturgeon because it had already disappeared by then.’
Now we are going to try to reintroduce the sturgeon. Is there any point?
‘Certainly. The fishing industry no longer poses a heavy threat to river life and many obstacles have now gone. Take the Haringvliet Dam, for example. Soon it will be left open. And these days the Rhine is less polluted. Moreover, climate change is making the sturgeon’s current habitat in the Gironde less suitable – the level of reproductive success there is now low – while by contrast the Rhine and Elbe are suitable as future habitats.’
How great is the chance of success?
‘That is difficult to estimate. The severity of some of the problems involved is unclear. Take the fishing in the North Sea. The key questions are in how many fishing activities is the sturgeon bycatch and can the fish be returned unharmed to the sea after the right treatment. While the Rhine is cleaner, its "estuarine character" – a dynamic river mouth where fresh water gradually becomes salt – has been lost. There are indications that habitat of this kind is less essential for success than was previously thought, but for the time being it remains unclear.’