Serina

Coventina tosses her children to her eldest daughter Ula before filthy, greedy, pirates took her onto their ship. Ula swims quickly away and rests at a large flat rock with her sisters. She hears her mother's singing voice and turns round, to see the ship crashing into dangerous rocks and it sinking to the floor of the sea.
For seventeen years later, the siren sisters have survived together, without their mother nor father who was human and died years before.
Talya just turning seventeen, is able to sing to attract a husband, and sing with her older sisters. She finds herself being away from her sisters for the first time when she wonders farther than normal and a dangerous storm takes her even further away.

Meanings of the names from oldest to youngest:
Ula ( sea jewel)
Assan ( waterfall)
Orabel ( beautiful sea coast)
Vanora ( white wave)
Talya ( dew of heaven)