oceans and lakes overcrowded with fish if female lay thousands of eggs?

You're right to wonder why oceans and lakes aren't overflowing with fish if females lay thousands of eggs! Here's why that doesn't happen:

* High Mortality Rate: A huge number of fish eggs and larvae never survive to adulthood. They become food for predators (like other fish, birds, and marine mammals), get swept away by currents, or succumb to disease. Only a tiny fraction of eggs ever develop into mature fish.

* Limited Resources: Even if many fish survived, there's a limit to the food, space, and other resources available in an ecosystem. Overcrowding leads to competition, which can result in starvation, disease, and even population crashes.

* Natural Predators: Predators play a crucial role in keeping fish populations in check. Without them, populations would explode and disrupt the delicate balance of the ecosystem.

* Environmental Factors: Climate change, pollution, and habitat destruction can also impact fish populations, limiting their ability to thrive even with high egg production.

* Life Cycles and Spawning Patterns: Not all fish species lay thousands of eggs. Some have fewer eggs but provide more parental care, increasing their offspring's chances of survival.

In short, while fish lay many eggs, a combination of natural factors like predation, limited resources, and environmental pressures ensures that populations remain relatively stable.