Each autumn, seals with lungworm infection are common ‘patients’ at Sealcentre Pieterburen, a seal rehabilitation centre in the Netherlands. They are among one of three groups that the seal rehabilitation centre takes in. The other two groups are pups that have lost their mothers – often due to human disturbance – and seals harmed by pollution in the sea. The centre aims not only to rehabilitate seals, but also to educate their visiting public on the Wadden Sea ecology, including relations with humans (Horst, 2021). Caretakers and veterinarians work to remove the internal lungworm parasite from seals and release the seals back into the Wadden Sea. Paradoxically, the common seal population in the Netherlands is at ‘carrying capacity’, meaning it has stopped growing because of limited food availability (Van der Zande et al, 2018: 4– 5). As such, despite the effort of caretakers and veterinarians, many seals – which are the top predators – may die because of pressure on food resources (Van der Zande et al, 2018: 4– 5). While animal welfare advocates argue for continued rehabilitation of individual seals to prevent the animal's suffering, ecologists call for a strategy that considers the health of the whole population (Felix, 2018; Van der Zande et al, 2018). Those at the seal rehabilitation centre try to navigate both positions. They have undertaken a science project which I will call ‘Project B’, asking which of those sick seals should be rehabilitated.

Inspired by multispecies approaches (Haraway, 2008; Van Dooren, 2014; Tsing, 2015; Lowe and Munster, 2016), I ask how lungworms, seals and humans navigate life and death with science Project B at the seal centre, as they become participants in practices of care and biopolitics. To help focus on how different beings are involved, and how they influence each other's actions, I draw on material semiotics. In this framework, the actorenacted (human or nonhuman) acts and influences others intentionally or unintentionally and is simultaneously enacted by others in a network. The ‘actor-enacteds’ are not in control but become in relation to others (Law and Mol, 2008: 58).