Who is S'reee from Deep Wizardry and what is their importance?

S'reee is a wizard, as well as a whale. She is just about to be promoted to Advisory Wizard when she and Ae'mhnuu are attacked by a fishing vessel. Ae'mhnuu is killed instantly and S'reee is badly injured. by one of the explosive spears now being used by hunters. Nita is called upon to heal her and as a result of Ae'mhnuu's death, S'reee is called on to become the Senior before she is ready.