[ELi5] How do fish get in lakes/ponds when there is no inflow of water
In: Biology
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Some fish eggs are believed to be resistant to the acid on bird’s digestive tract. So, sometimes a bird may swallow an egg, and if the egg is shat on a lake….
Basically they got cut off.
There is an interesting lake in my country, Lake Taal its actually a Caldera of an active volcano that used to be connected to the sea. A few centuries ago in recorded history an eruotion cased it to be blocked from the sea.
Saltwater fish eventually evolved to survive the lake.
https://www.cntraveler.com/stories/2013-01-21/taal-lake-luzon-philippines-maphead-ken-jennings
There is a lot of doubts fish eggs sticking to the feet and feathers of waterfowl. Maybe it occurred, maybe it didn’t a lot of it is unproven. Some fish eggs have even survived going through the gut, and viable eggs have been hatched from duck poop in a lab.
The most common answer is modern lakes and rivers might have been interconnected during prehistoric floods and ice ages.
And in the case of some species like trout, it’s because humans brought them there. Brown trout are pretty much all over the world. For example, upstream of the waterfalls in Yosemite, Europeans either hand carried buckets of fish, or on packed mule/horse trains. As a way to store food they could later catch.
Today, all over the world, various government agencies stock fish for recreational fishermen, transported on tanker trucks or even released from helicopter and airplane.
Stocking is very common in Maine and the Department of Inland Fisheries and Wildlife publishes a report with the number of each species/size stocked in each body of water.
In some lakes and ponds, humans send a truck full of fish to “stock” the lake, this is common practise where I live (Canada)
1. Birds bringing eggs by accident
2. Huge Floods (e.g. like currently in Germany)
3. Lakes etc. separating over time, cutting off parts.
4. Seasonal changes, flooding etc.
I literally was just watching a TikTok of planes dropping fish like crop dusters into lakes in Utah…Eli5
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