1M chinook salmon released into Sacramento River

https://www.sfgate.com/bayarea/article/Quite-a-sight-1M-chinook-salmon-released-into-12887949.php

The article says that only 1 in 1000 to 1 in 10000 are expected to return---pretty long odds.

Read the part about return rate again.

"On this particular release, the success: We may get 1,000 to 10,000 fish back out of the million," said Harry Morse with the CDFW."

That makes the return rate ("odds") between 100 to 1 and 1,000 to 1, so it's not quite as pessimistic.