Final answer:
Estuaries are excellent nursery grounds for commercial fish and shellfish due to the abundance of nutrients and the relatively low number of predators.
Step-by-step explanation:
Estuaries are perfect nursery grounds for many commercial fish and shellfish because they contain large amounts of nutrients and relatively few large predators. Estuaries provide a protected area where the young offspring of crustaceans, mollusks, and fish can begin their lives. The mixing of fresh water from rivers and salt water from the ocean creates a unique environment that supports the growth and development of these commercial species.