Environmental and animal rights groups in Mexico are training their sights on the growing number of "swim with dolphins" enclosures on the nation's coasts.

The movement scored its first victory Thursday, when federal regulator authorities said they had ordered a dolphinarium just south of the resort city of Cancun closed because it had not filed an environmental impact statement.

The facility operated by Grupo Dolphin Discovery said it had been operating for two years with all appropriate permits. But it acknowledged it had only filed its impact statement in January.

On Friday, the animal-rights group PETA sent a letter to Mexican authorities asking that dolphin acts be included under a Quintana Roo state law that bans the use of animal acts in circuses. PETA said the dolphins suffer stress.