Spawning of salmon is such a peculiar process it‘s been featured in many documentaries and even animation a number of times. Salmon travel thousands of miles across the ocean to spawn in the place they were born themselves. However, some of them don‘t make it back. Now scientists say that by dying these fishes are actually helping their offspring.
This migration is so exhausting many salmons don’t make it much further. Hundreds of fishes die after spawning and decay in these waters. Now scientists from The University of Glasgow say that these decaying bodies of fish actually fertilize the area, creating environment which is beneficial for younger fish and maintains their genetic diversity. The streams that have less of these rotting fishes have less food – less insects that are one of the most important sources of food for salmon offspring. This means that more salmon offspring does not survive for a longer time.
Interestingly, areas with less decaying bodies of salmon favour a smaller number of families. This means that genetic diversity is lost and the newborn fish are less fit for survival in the changing climate. Scientists came to these conclusions after an experimental research. They manipulated levels of nutrients from decaying carcases in several streams: five of them received reduced level of nutrients, while the other five got the usual amount of nutrients from rotting carcases. Other parameters of these streams and the offspring in them did not differ. Scientists returned five months later to observe the impact of these differing levels of nutrients.
Scientists noticed that reduced levels of nutrients from decaying parents caused reduction in food for the offspring. This meant that survival rates were much lower and gene pool was also impacted in a negative way, as was revealed by DNA fingerprinting. Professor Neil Metcalfe, coordinator of the study, said: “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 very own destiny.”
While the picture may seem grim, dying adult salmon fertilize waters for the better life of their offspring. It may be a morbid image, but it is a vital piece of the process.
Source: The University of Glasgow