Ok guys, I figured out exactly what is causing this. There is actually a hole in the landscape in the water area where the sharks are. This means that this area is accessible to the sharks for spawning/swimming purposes, but it also means that you can get there too. If a shark is green, it means he has been killed already and you are just missing one of the brood or something. There is a small hole in the water area that you can just swim through to go into a weird land of clipped images and lost sharks. So just look for it and you can complete the challenge. I discovered this for myself in Yaks Bend server just now. You’ll probably have to wp out though, because I couldn’t find the exit for the life of me.
