The Evolution of Fish

Written by Alex Ortmann, ESLLC 2016-2017

Researchers from the University of Turku, in Finland, published a new studying showing the removal of fish on a sized based scale leads to massive gene expression changes in experimentally exploded fish.  The studies were done on experimental zebrafish populations, where over five generations, the largest fish where harvested by either removing the largest ones directly, or removing the fish randomly by size. After, the fish populations where allowed to recover for six generations. The findings revealed that experimentally removing fish by size caused a difference in the expression of 4,000 genes some associated with changes at the DNA level. Furthermore, after six generations of recovery, the genes never went back to their original state.

These findings bring up strong problem threatening both the health of our oceans and the fishing industry, which is a major source of food for billions around the world. The removal of the largest fish from a population, results in the small gene pool to bread. Therefore, the fish population grows closer in physical characteristics, and has a dramatic decrease in genetic variation. This means a fish population is more susceptible to widespread die offs, but is also much less likely to adapt to changes in the environment or climate which will likely come in the future. However, if policy is instituted, protecting the larger individuals of a species, the recovery rate of fish populations could increase, and be more sustainable in the future.


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