An Ocean-Dwelling Fish Genetically Adapted to Freshwater in Just 120 Years

[Judi Lynn]

Nature is incredible.

PURDUE UNIVERSITY 24 JUN 2018

Steelhead trout, members of the salmon family that live and grow in the Pacific Ocean, genetically adapted to the freshwater environment of Lake Michigan in less than 120 years, according to new research.

Steelhead were intentionally introduced into Lake Michigan in the late 1800s in order to bolster recreational and commercial fisheries. In their native range, which extends from California to Russia, steelhead hatch in freshwater rivers, migrate to the ocean, and return to freshwater to spawn.

This migration allows steelhead to feed in the ocean, where they can grow larger and produce more eggs than if they remained in freshwater streams for their entire lives.

The steelhead introduced into Lake Michigan continue to spawn in small freshwater tributaries and streams, but now treat the entirely freshwater habitat of the Great Lakes as a surrogate ocean.

More:
https://www.sciencealert.com/an-ocean-dwelling-fish-genetically-adapted-to-freshwater-in-just-120-years

[Uncle Joe]

1. That was a good read

Thanks for the thread Judi Lynn

[mr_lebowski]

2. I didn't read but I'd guess there's genes in many fish allowing for survival in wide salinity ranges

Esp. those where they can generally live in fresh OR salt water, and all they have to do is adjust where they feed as adults ... if cut off from where they would normally do so. Probably take a lot longer to adapt to laying eggs in salt water for a fish that normally lays them in fresh water ... but fish that lay eggs in fresh water probably long ago developed the ability to live even if they can't back to the ocean. Seems like something that would happen fairly regularly over the millions of years of their evolution.

[marble falls]

3. Goood stuff!