In one of the towns I used to live in there was a blue ribbon trout stream, with the most productive stretch being the 20km downstream from the effluent pipe. There were 2 types of trout, one bred in the river and the other migrated to a small set of mountain streams to breed. The ones that bred in the river would produce mostly female offspring (phenotypically) even though they were 50/50 genotypically. Birth control pills, pseudo estrogens in detergents and plastics were implicated. I don’t know if plants would pick those types of chemicals up but interesting. There is a doco from a series “the doc zone” season 3 episode 8 called “the disappearing male” about a similar thing which is a good watch if you don’t mind government sponsored Canadian public television.
Maybe the females were released by fishermans asociations or by hatcheryes.
You can buy all female or 50/50 or diploid fertilised eggs.
The trout eggs from the poluted with sewage river were most likely shocked .
Its a common procedure for the trout breeders to shock the eggs so that they have more females wich is desirable because they grow double as fast than the males.
Diploid trouts wich are sterile grow even faster than females and 95 percent of the aquacultured rainbow trouts from supermarkets are triploids.
I like to say about rainbow trout thats almost like a carp but brown and brook trouts are much more sensitive to polution ( ie low oxigen) and they really need cold water.
Usually brown trouts are the coldest here and the most sensitive than even brook trout but we have here somme small deep water brook trout species that are super sensitive.
Thos tiny ,most super sensitive brook trouts we have here are called ,,fantanel,, from fantana wich means well.
In old times ,people here used to add a such small brook trout to live in a water well so that they knew the water its clean and safe to drink.
Even today in romania we call the brook trouts ,,fantanel,, wich means the fish of the well.
The hormones,estrogens from sewage ,etc,they are organic compounds wich disintegrate verry fast .
I wouldnt worry about them and i dont think il see the frogs turned homosexual in the sewage trench.
With the new regulations from the EU on the enviroment,we will soon have almost drinkable water from the sewage.
I will probably regret that theres too little fertiliser in the sewage stream
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