The eels we find in our Somerset waterways and wetlands may
spend more than 25 years in freshwater, on average males spend 10–14 years in
freshwater and females 12- 20 years. We can only age eels by examining the
otoliths or ‘ear stones’ in their head which lay down growth rings like the
rings of a tree.
On dark nights in autumn and winter, normally with the river
in flood, silver eels migrate en masse down our river catchments. They are
single-minded in their quest and, surprisingly, will move overland through wet
grass to get to a stream or river from an isolated pond. They will even swim
into noisy pumps and turbines in order to reach the sea.
In the last few years some pumping stations have been
adapted to use ‘fish friendly’ pumps but many remain as either obstructions to
this migration or as outright ‘killers’.