Besides small fish, what key invertebrate food source is vital for wild salmon, especially when small fish are scarce?

Answer

Crustaceans, such as krill and euphausiids

Crustaceans, described as tiny, shrimp-like creatures like krill and euphausiids, constitute a vital food source for wild salmon, particularly in marine areas where smaller fish are less available.

Besides small fish, what key invertebrate food source is vital for wild salmon, especially when small fish are scarce?
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