Sounds like you’re worried about transporting the creatures up the water column. “By-catch” of the human-driven circulation if you will.
I was thinking of the opposite problem. The creatures stay in the deep. But as we “mine” the deep cold water by drawing it up, there’s a net motion of thermal energy down. Despite the fact warmer water floats on colder.
The end effect is we pollute their deep cold environment by making it an equally deep but warmer environment. Which may upset their delicate sensibilities and ecosystems.
The deep ocean is a lot like a desert. It’s biologically inhospitable and anything surviving there is barely getting by in some carefully honed narrow niche. Whacking a deep ocean or a desert has a lot more opportunity to create mass die-offs than does whacking a thriving temperate forest.
Thats why you’d pump the hot water down and mix it with the water in the depths ?
BUT, reducing the temperature of the waters surface reducing the cooling of the earth… because warmer water loses heat faster, that would be to space on a clear night , it can be backward to desired effect… Cooling the surface can increase the average temperature of the ocean … thus making the treatment backfire ??
Basically warm ocean surfaces is a symptom of global warming. There’s no treatment of that symptom.