Could this Asp-Turtle keep itself satiated?

Question

The asp-turtle is a truly huge reptilian whale

Its dimensions are 40m across and 200m long. To achieve this, its bones and tissues are very strong, strong enough to allow it to swim like a smaller animal, such as a blue whale. These stronger tissues do not need extra energy to form, and only the muscles need extra energy (because they do more work)

They swim using their tail, which is whale-like, and a pair of large flippers found on their shoulders. They are pleustonic, spending almost their entire lives floating with their backs and nose out of the water. Their head and neck is a lot like a turtle, though with a relatively large snake-nose that points up for easier breathing. They breathe air. The rest of their anatomy is like that of a whale

The oceans they inhabit are very much like oceans on Earth in reality, as is the atmosphere. However, unlike Earth there are more large sea-creatures, and there is around 10% more energy being pulled in by marine producers

Could this species realistically get enough nutrients and oxygen to stay alive in the conditions described above?

Answer 1

I worry the pleustonicity will be too limiting.

A thing that size will be a filter feeder. That is the only way to get enough food. Big whales are all filter feeders. But whales have the entire water table to work from. Whales pursue agglomerations of food wherever they might be from shallow to deep. Your creature stays on the surface and so is limited to filterfeedable food that might be at the surface.

The other question is how well the turtle body plan would lend itself to the filter feeder lifestyle. Not too well I suspect. Dailey had a fine question about exactly that: How Would a Filter-Feeding Marine Turtle Feed?