On Bivalves

     There is occasional debate within the vegan community about whether it is morally permissible to consume bivalves, whether doing so is consistent with the idea of veganism, and whether you should call yourself "vegan" if you do. The stance that eating bivalves is consistent with the ethical stance of veganism is sometimes called "ostroveganism" or "bivalveganism," however some people who do this just refer to themselves as "vegan," not seeing the need for a separate label when they see bivalves as consistent with veganism. This idea is relatively controversial, and it appears that most vegans are opposed to this. That said, I wanted to write a bit about the issue, and my argument for the consumption of bivalves will largely be negative utilitarian in nature. 

On the Sentience, or Lack Thereof, of Bivalves

     Firstly, I would encourage any reader to check out "On the Consumption of Bivalves" by David Cascio published on "The Animalist" Medium page. He does a great job discussing the idea of whether bivalves are sentient or not, in addition to discussing the environmental and nutritional aspects of bivalves. He argues that it is unlikely that bivalves are sentient, and even articles that are more sympathetic to the idea that bivalves may be sentient, such as the article by Animal Ethics, acknowledge that "there is still uncertainty about bivalve and snail sentience." On the flip side, a report by Wageningen University discussing behavioral adaptations of bivalves in response to their environment states "these types of papers indicate that bivalves might indeed be sentient." That said, they also acknowledge that "the quantity and nature of these available biological studies do not sufficiently demonstrate a firm conclusion that the welfare of bivalves in aquaculture is a relevant topic at the moment." Further, and this is something David Cascio discusses, the concept of "behavioral adaptations" does not necessarily equate to sentience. Plants are capable of such adaptations, and yet they are not sentient (see 1, 2, 3, 4, and 5). Thus, the data reviewed by Wageningen University does not amount to sentience, and they rightly acknowledge this. This is, of course, a nuanced topic, so I would encourage the reader to read all of the linked papers/articles and continue to look into this topic. That said, it suffices to say that there is no consensus that bivalves are sentient. 



Environmental Impacts 

     If we look at the greenhouse gas emissions of bivalves, and you can find them at the bottom of the chart, they emit 1.4 kg of carbon dioxide equivalents per kilogram of food. This is lower than basically all animal based foods, and is lower than many plant based foods. For example, tofu is listed as 3.16 kg, and rice at 4.45 kg.It is also lower than legumes (listed as "other pulses"), wheat and rye, and oatmeal. Eutrophication, which typically refers to the pollution of bodies of water with excess nutrients such as nitrogen and phosphorus, is something we need to consider as well. Eutrophication can lead to deadly algal blooms, harming marine life. Bivalves don't just perform well here, but actually help remediate this problem. While most animal based foods are predictably worse here, all plant based foods contribute to eutrophication. However, bivalves are associated with net negative nitrogen and phosphorous emissions. This is because they filter water, cleaning it, and helping to remove excess eutrophication. This study noted that "Bivalves are filter feeders, filtering water and particulates, creating substrates which provide habitat to act as nursery grounds for other species" and also notes "The most important regulating services are nutrient remediation. Cultivated bivalves remove 49,000 tonnes of nitrogen and 6,000 tonnes of phosphorus, worth a potential $1.20 billion." Regarding their first statement about bivalves providing a habitat for other species, it is indeed true that bivalves increase biodiversity, and that practices such as rope-grown bivalves minimize potential negative environmental effects of farming them.Their ability to clean water and boost biodiversity means that bivalve cultivation also plays a role in habitat restoration, including commercial bivalve farming.


     Other environmental upsides of bivalves farming is that there is no pesticides associated with it. Pesticides not only kill insects, but other animals that too, such as those that often eat insects, like birds. A concerning issue here, aside from harming animals such as birds which are known to be sentient, is that there are arguments that insects are sentient, and the Wild Animal Initiative estimates that 3.5 quadrillion insects are killed every year in the US from pesticide use. Being that there is less evidence of bivalve sentience vs many insects, this is potentially a large ethical advantage for consuming bivalves. Another consideration is that, since bivalves are farmed in water, there is likewise essentially no land use associated with them, whereas all land based agriculture uses some amount of land. Being that half of the world’s habitable land is used for agriculture, which contributes to things like deforestation, destruction of local habitats, etc. This is thus another benefit of bivalves. All in all, bivalves seem to have little in the way of incidental deaths associated with them, even much less than plant based agriculture. 

Nutrition

     Bivalves are very nutrient dense and are high in many vitamins and minerals that can be harder to get on a plant based diet, including B12, omega-3 fatty acids, choline, iron, selenium, and zinc. Being marine animals, the omega 3's are DHA and EPA, which is absent in a plant based diet unless you are supplementing algae oil, and bivalve consumption increases your omega 3 index. B12 is likewise absent in a plant based diet sans supplementation, and heme iron in bivalves might be beneficial for someone who tends towards lower iron. In addition, they also have some other nutrients such as smaller amounts of some other b vitamins, choline, vitamin a, e, calcium and some other minerals, in addition to being considered low in mercury. Further, the protein in bivalves is high quality, being an animal based protein. Thus, I think it is safe to conclude that bivalves are relatively healthy and especially compliment an otherwise fully plant based diet well. 

     Further, it could be argued that this would help some people stay vegan (or rather, ostrovegan), or perhaps help attract someone to (ostro)veganism in the first place. There is this perception among many that vegan diets are not healthy, meanwhile the available data from a survey suggests that only about 3% quit for a defined health reason, with another 3% quitting over a vague health compliant such as "didn't feel good." Either way, the nutritional aspect of an (ostro)vegan diet may seem more appealing if bivalves, which are very nutrient dense, are allowed on this diet. It could also mean that a vegan who is not supplementing B12 or otherwise not planning their diet well could get B12 and other harder to get nutrients from bivalves and potentially not run into health issues they otherwise might, perhaps preventing them from quitting veganism. Thus, even if you view bivalves as not vegan (and thus not "good" ethically), the question is whether you would want someone to be "almost vegan" or revert back to eating dairy, eggs, and maybe even meat, which would certainly be more harmful than eating bivalves.

 Conclusion 

     There is a lack of evidence for the sentient of bivalves, but an abundance of evidence that their cultivation for food is environmentally friendly, results in much less incidental deaths than any sort of land based agriculture, and that they are healthy and compliment a plant based diet well. Thus, I think there is a strong argument that bivalve consumption is ethical, regardless of whether it is considered vegan or not.