Question

If fish populations in the Antarctic were to decline, what would be the best way for the smaller toothed whales to adapt?

Answer 1

Answer:

Beat more baleen whales

Explanation: 

Smaller toothed whales are secondary consumers of fish. If the fish population declined, the populations of leopard seals, elephant seals, and penguins; animals which make up a large portion of the whales' diet; would likely also decline. 
To survive, the smaller toothed whales would have to eat more animals that feed primarily on krill instead of fish, such as seals (not leopard or elephant seals) and baleen whales.