What is a suggested secondary role for the dramatic display of the sailfish's raised dorsal fin?

Answer

Intraspecies communication or dominance signaling.

Studies suggest that the deployment of the highly visible sail, marked with contrasting blue-black spots, may play a role in signaling dominance or communication between individual sailfish.

What is a suggested secondary role for the dramatic display of the sailfish's raised dorsal fin?
oceanfishspeedBillSailfish