Researchers at IMARES, part of Wageningen UR, have got smelt taken from the IJsselmeer lake to spawn, which is an unparalleled result for this species.
They are still only eggs so some caution is in order. Even so, researcher Marieke Keller has already treated everyone to 'beschuit met muisjes', the traditional biscuits with aniseed topping used to celebrate births in the Netherlands. She reckons this is fitting given the achievement. 'Smelt is a very difficult species to keep. It is quite unusual even to get them alive into the lab from the IJsselmeer and Markermeer lakes as they are very vulnerable.'
But that was not the end of the story. The researchers even managed to get the smelt to spawn 'spontaneously' by 'playing with the light and temperature'. Keller says this has never been done before in the Netherlands or the rest of Northern Europe, the natural habitat of the European smelt. Keller expects smelt young to appear in about one to two weeks in the IJmuiden lab.
The experiment is part of the Autonomous Downward Trend project, which aims to provide a picture of the entire food chain in the IJsselmeer and Markermeer lakes. The bird and fish populations in both these lakes have fallen sharply over the past few decades. It is not clear why this has happened, let alone what can be done about it. Smelt is a key component of the diet for many birds, including various terns, the sawbill and the grebe.
Climate change may be a factor. If the larvae emerge too early, there will not be much food available and a large proportion of the larvae will die. On the other hand, if the larvae emerge too late, they will not have enough time to grow sufficiently big to escape from their predators. In both cases the consequences for the food chain as a whole could be huge. That is why a better understanding is needed of the effect temperature has on the rate of development of the eggs