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Human Activity and Super-speed Fishy Evolution

Evolution is a long and slow process. However, the human activity has pushed this million-years long process into an ultra fast process which only takes decades. How could this happen?

Currently, due to human interference, the environment has been changing very fast. The animals are changing, while it might sound cool that these animals can adapt so quickly, these are the proof that they are under severe environmental stress.

Overfishing is one example of how human activity affects the fish species like salmon and cod. Chinook salmon took 30-40 years to have their size only 3/4th their usual size after they were over-harvested in the early 1900s. Now, the average chinook salmon adult fish is 20% smaller, mature earlier, and with only 75% live expectancy compared to their ancestors.

In general, humans favor longer-living and bigger fish catches. The smaller fish are less likely to be caught by humans. Most of the fishes that mature earlier also enable them to have offspring earlier too. This might sound advantageous, but this change actually poses dangers to the salmon farming industry as the quick-maturing fish reach smaller market sizes faster.

So it just affects the economy right?

Sadly, the changes in their sizes are shown to impact the ecosystem too. Aside from the changes in their life-cycle biology, the chinook salmon hyper-speed evolution impacts both the ecosystem and human life. As you might already know, salmonids (or salmons in general) travels miles and miles for their entire life. Along with their travel, they help transport nutrients from one place to another place with their eating process. At the end of the life cycle, there is also a significant reduction in egg production with an average reduction of 16%. This reduction in egg production and body size ultimately affects fisheries and also fish caught by the rural people who rely on wild-caught fish for daily consumption.

However, the demand for these fishies is not decreasing, in fact, the fish demand is continuously increasing. Currently, most of the fish in the US and EU markets are farm-raised. Hopefully, the policymakers will not let the fishermen catch the smaller fish because if they do, imagine what could happen to the wild population when they can no longer 'super-evolve' to avoid being extinct.

I love to eat fish, and I still eat them because I think the wild-caught fish has a lower carbon footprint so I think I am partly responsible for the demand. Writing this article, I just realized how important it is to know how your food is produced. The changes with salmon biology show how real the human impact is on nature.

How about you, have you noticed any changes in the animal (behaviors or biology) in your environment due to human activities?

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