"We need to keep as many alive as possible, because we depend upon their existence more than we realize."
No, we don't. It seems you have accepted the enviro-socialist premise that all life is connected (Gaia hypothesis), that the earth is alive.
Consider that we killed nearly all of the largest organisms ever to live on earth - the Blue Whale. Removing that top carnivore in the Antarctic Sea did nothing except make a lot of krill very happy.
The food chain stayed as it was (minus Blue Whales) and when they came back, little or nothing changed.
But there were unhappy krill. ;-(
The interdependence bit is simply not the major factor the enviro's want us stupid, taxpayers to believe
Just ask yourself,"Is this world
any worse off without the Sabre-tooth tigers?"If I were in charge,that fish would be on a slab in a Japanese fish market.