Complex sentence: She stays with 50,000 eggs for six weeks (incubation period), but when the eggs hatch, she is already dead from starvation or is too weak to fight off predators, so they kill her.
Split into simpler sentences: She stays with 50,000 eggs for six weeks (incubation period). When the eggs hatch, she is either already dead from starvation, or is too weak to fight off predators, so they kill her.