I dont overpopulate laggons, ever (unless its with ichtyosaurus or plesiousaurus), i only had 2 liopleurodons ALONE, one single mosasarusus, and two kronosaurus.. each species in different lagoons... sooner or later, they start to starve and miss the food sources. Althou the mosasaurus will still do the animation to catch the sharks, but completely useless.
No, i dont use any mods. But i also discovered that this also happens everywhere around in land enclosures. Cant tell species but i saw a few of them already... sigh.