What specific parts of the sailfish are highly vulnerable to severe stress or injury if handled improperly during release?

Answer

Delicate gills or the base of their bill.

Improper handling, such as keeping the fish out of the water for too long or pulling too hard, can cause severe stress or injury to the sailfish's delicate gills or the base of its bill.

What specific parts of the sailfish are highly vulnerable to severe stress or injury if handled improperly during release?
oceanfishspeedBillSailfish