The athlete, who blasted the meat industry for 'animal torture' last year, reposted a graphic image from Save The Reef of the annual culling of cetaceans that takes place in the Faroe Islands.
He also included the photo's original caption, which described how the animals are killed - a 'tradition' that has allegedly been going on since 1584.
'Stabbed with a spinal lance'
"The fishermen enter the water in boats and as soon as pods of whales arrive close to the bay, they surround them and lead them towards land to be beached and slaughtered," the Instagram post reads.
"When the whales are close enough, a hook is inserted into their blowholes to bring them further up the shore and their necks are then stabbed with a spinal lance and their spinal cords are severed, which further cuts the blood supply to its brain.
"The whale loses consciousness and dies within a few seconds."