Each Autumn museum staff take up spawning sea trout that have made their way up the fish ladder and squeeze them for milt and roe. For genetic variation, several different males and females are chosen. The milt and roe are mixed in the same bowl. In order to prevent the eggs from developing too fast, the incubator is kept at 4 degrees C.

 

 

 

 

One litre roe contains 6-8 000 eggs and can be fertilised by a drop of milt the size of a pinhead. The roe in the picture is just over 3 months old.