No.
There is no line to the Cíes Islands from Bueu. Bueu is a departure port for Ons island, another island in the same national park. There is no service to the Cíes from here, though.
The nearest port that works
From Bueu, the practical move is to head to Cangas do Morrazo and board there: €24 per ticket and 7 departures a day in high season.
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If you want more flexibility, Vigo runs up to ten daily departures in summer and is the cheapest port.