For any animal, releasing sperm cells requires a bit of time and energy. Using up so much energy can keep them from the other required work of survival, including finding food and water or sleeping.

The amount of sperm released decreased sharply with each mating during a single day, reducing the males' fertilization rate.

On average, the males were able to mate 19 times per day. The team was most interested in the amount and quality of the sperm after each of these matings. During the first three matings, the fish ...

This impacts reproduction due to the fact that groupers only reproduce at spawning events, when fish from a certain area congregate to find a mate at a specific location a handful of times per year.