Seaweed aquaculture is expanding rapidly as a sustainable food and material source, with generally positive welfare implications compared to animal aquaculture.
Seaweed farming is notable for its relative absence of direct animal welfare concerns - macroalgae have no nervous system or pain receptors. The welfare considerations are primarily ecological: poorly sited seaweed farms can reduce water flow and light penetration, affecting the animals living in and around the farm site. Dense seaweed cultivation alters habitat structure in ways that benefit some species (providing shelter) and disadvantage others (reducing phytoplankton and light). From a welfare perspective, seaweed aquaculture compares extremely favorably to fish and shellfish farming, making it an attractive component of sustainable ocean food production. Its expansion as an alternative protein and material source reduces pressure on more welfare-problematic animal production systems.