When the Polynesian Voyaging Society’s two double-hulled canoes embark on their unprecedented worldwide sail next month, they aim to spread a message to protect what the group has dubbed "Island Earth." But they’ll need the help of environmental leaders back home to put that call for stewardship into practice.

On Wednesday, members of about 21 environmental groups and state and federal agencies gathered on the deck of the renowned Hokule‘a canoe to pledge support for the voyaging society’s upcoming circumnavigation. Each signed a promise to further goals at home consistent with that journey, and to improve how the islands’ coastal resources are managed.

"We are sailing to protect what we value and love about our home," PVS President Nainoa Thompson said at a briefing with those representatives before the signing. "It’s for our children, but it’s about taking care of our children’s home. The people standing behind this table are the power behind it."

The legally nonbinding pledge calls on the local signatories to work to restore fishponds and fish populations close to shore to help boost local food sources — and to eradicate invasive species, reef-killing sediment and debris from marine habitats — along with 18 other conservation measures. They used a special smudge-proof pen to sign the waterproof document, which Hokule‘a’s crew will take with it on the journey during the next four years.

Among those who signed were William Aila, the state’s chief land management official, who heads Hawaii’s Department of Land and Natural Resources.

The voyage, called Malama Honua, "has already resulted in change, positive change," Aila said Wednesday.

"You carry the aloha that Hawaii is known for, the forgiveness that Hawaii is known for," he told Thompson. "Everyone here, wishing you folks calm waters and smooth winds, understands that change has already come about" because it’s brought together key environmental and conservation leaders, he added.

Hokule‘a and its new escort canoe, the Hikianalia, are slated to leave Sand Island for Hilo on May 17. From Hilo, the two canoes will leave on the voyage’s first leg, to Tahiti.