We currently farm 550 aquatic species for food around the world, and octopus is about to become the newest addition to that list. But a concerned team of international researchers write that farming these cephalopods at industrial scales will dramatically intensify the environmental impact of aquaculture–and put us in ethical hot water, too.
Wily, territorial, and difficult to breed in captivity, octopus might seem like an unconventional choice for aquaculture. Yet a growing number of countries, including Italy, Australia, Japan, China, and Spain, are trying their hand at ‘ranching’ these animals, whereby wild-caught juvenile octopus, or eggs from a hatchery, are raised in captivity. Japan, in particular, is making headway–promising that by next year it will successfully be producing fully-farmed, market-ready octopuses.
But adding octopus to aquaculture’s repertoire will worsen its already strained environmental record, write the researchers in the journal Issues in Science and Technology.
Like conventional fish farming, farming octopus at high densities would produce large amounts of faecal waste that would escape into the surrounding environment, polluting it. The application of antibiotics to octopus pens–an essential for keeping diseases in check–would similarly infect the sea or soil where octopus are farmed. Octopus are large animals, meaning that farming them would also require more space, most likely leading to the destruction of natural habitat in cases where the animals are contained in pens on land–a problem that already blots aquaculture’s record.
But perhaps the biggest threat that the researchers foresee is that octopus are carnivorous animals that would require vast amounts of feed, made from wild-caught ocean fish. Already, aquaculture uses up one-third of the global fish catch. Octopuses have a feed conversion ratio of 3 to 1, the researchers write, meaning they need three times their body weight to sustain them. Thus, producing large quantities of farmed octopus would likely worsen global overfishing.
Beyond the environmental impacts, the welfare of these animals in captivity is also much harder to ensure than regular fish, the researchers caution. Studies point to the impressive cognitive abilities of octopus, and their behavioural complexity. As relatively solitary animals, they are also often aggressive towards others in their vicinity. Conventional aquaculture–where animals are confined in crowded enclosures with little to occupy them–would be unsuitable for the needs of these animals, the researchers say. If farmers did try to accommodate their needs, that would likely require more space, possibly compounding some of the already-existing environmental challenges of aquaculture.
These factors would seem to thoroughly destroy the case for octopus farming, yet there are powerful financial incentives driving this trade. The push towards octopus aquaculture comes as wild stocks of these animals are gradually being depleted by overfishing, the researchers explain. In parallel, a growing market for octopus, mainly in wealthy nations, is fuelling research and investment in this lucrative–albeit challenging–form of aquaculture. As investment grows, the researchers fear that “the technology may well become available to farm octopus at an industrial scale”–making it a reality.
In the face of this, the researchers make the case that we really don’t need to farm–or necessarily even eat–octopus, at all. The countries where they’re in demand are largely food secure, and octopus is not required for human wellbeing, they point out. Rather, it’s something of a luxury food.
Ultimately, they frame this strange new environmental conundrum as an opportunity to avoid some of the blunders we’ve already made with industrial food production on our planet. “There are better directions for the future of farming,” the researchers say.