Days after voting to ban the use of dolphins captured during the controversial Taiji dolphin hunts, the Japanese Association of Zoos and Aquariums (JAZA) has revealed that notorious hacking group Anonymous has stolen the phone numbers and email addresses of its members, as well as other sensitive data.

JAZA said in a statement that the network of hackers and activists managed to infiltrate two JAZA websites, retrieve member-only information and publish the data online. In response, the body temporarily shut down the websites affected by the security breach.

Among the data stolen are details of species procurement (including the Taiji dolphin hunts) and the breeding records of animals held by JAZA members.

The data was released around 60 days ago, along with messages protesting against the capture and display of dolphins and killer whales at Japanese aquariums. It was only after the recent vote thatJAZA chose to reveal details about the leak, which included the email addresses and phone numbers of around 2,350 individuals employed at 130 of JAZA’s 152 member facilities, of which 63 are aquariums and 89 are zoos.

“We are at risk of further attacks, so we stepped up security. We have also alerted member facilities and asked them to change their workers’ email addresses,” said a spokesperson for JAZA.

Japan’s Taiji dolphin hunts have gained notoriety in recent times thanks to documentary film The Cove, which shows the brutal manner in which the highly-intelligent cetaceans are being hunted. JAZA represents aquariums which have taken dolphins from these hunts and was recently almost kicked out of the the World Association of Zoos and Aquariums (WAZA) before banning the use of dolphins captured using the drive fishing method. In response to the ban, five of JAZA’s aquarium’s have said they may leave the association.

Anonymous had previously criticised Japan over its whaling activity and had levelled a number of threats against the country in a series of YouTube posts in 2013 and 2014. At this time, it is unclear what the hacking group’s next move is.