LIMA (Reuters) - Peru said on Friday that it might restrict shark fishing to curb the illegal slaughter of up to 15,000 dolphins per year - used as bait by informal fisherman - following the release of footage documenting the practice.

Video taken by NGO Mundo Azul broadcast on Thursday shows Peruvian fisherman harpooning dolphins, whose capture is banned under Peruvian law, before skinning and throwing their bloodied parts back into the ocean to lure sharks.

Mako and other shark species are sold legally for export, especially to Asian countries who consume their fins as a delicacy.

"We will pursue those committing these crimes," Deputy Minister of Fisheries Paul Phumpiu told reporters. "We are considering all forms of action, from bans and restrictions to - in extreme cases - the prohibition of (shark) commercialization."

Phumpiu said that a government investigation into the process should be completed by mid-2014.

Mundo Azul estimates that between 7,000 and 15,000 dolphins are killed in Peru every year because of the technique.

"It is clear that the entire fishing fleet for sharks in Peru is involved in a systematic killing of dolphins," said Stefan Austermuhle, executive director of Mundo Azul.

(Reporting by Lucas Iberico-Lozada and Reuters TV; Editing by Sandra Maler)