Salmons’ sacrifice ‘helps shape the future’
THEY are known for making a gruelling – and ultimately fatal – upstream journey to reproduce, but their sacrifice benefits future generations.
According to scientists at Glasgow University, the decaying bodies of salmon fertilise the waters and help fry to grow.
A study found that rivers lacking dead salmon have fewer insects for young salmon to feed on, meaning surviving fish are smaller and belong to fewer families. The resulting loss of genetic diversity could make these salmon populations more vulnerable to extinction as their surroundings change.
The university’s Professor Neil Metcalfe explained: ‘The longer-term consequences of these parental nutrients are bound to be complex, but these findings indicate that salmon shape their environment in a way that alters their destiny.
In a detailed study of burns in the north of Scotland, the researchers tested what happened when they manipulated levels of nutrients that would come from decaying salmon carcasses during the winter spawning season.
Five stretches of water received the normal level of nutrients, while another five had low nutrient levels – but all ten got the same number of salmon eggs from the same group of families.
Evolutionary ecologist Dr Sonya Auer said yesterday: ‘Our surveys, backed up by DNA fingerprinting, show that fewer families of young salmon survived in the streams that lacked parent carcasses.’