Are you suggesting we should prefer to eat fish from species that are already overfished, to make their populations even more depleted and thus reduce the number that are suffering?
If that were the only important effect, maybe, because I’m also suffering-focused. But I’d rather say that I’m clueless about whether eating fish is good or bad. There are also other effects, like on small wild aquatic (and for farmed species, terrestrial) arthropods that could end up dominating and could go the other way, but I haven’t thought enough about them. I think this is a reasonable position whether or not you’re suffering-focused, as long as you’re roughly utilitarian of some kind.
I think even with this line of thinking, the growth of insect farming specifically for use as feed for farmed aquatic animals probably tips this in the direction of “bad”.
(Edited to correct my math and add the example at the bottom.)
That sounds possible to me, but again I feel very unsure and would want to work through some models before deciding. It still seems possible to me that the effects on wild arthropods (aquatic and terrestrial) could outweigh, even vastly outweigh, the effects on farmed insects. It could depend on which arthropods you count, what probabilities you assign to their consciousness and their expected moral weights, though, e.g. mites, springtails and zooplankton might be too unlikely to be conscious or not matter enough overall, but I suspect the number of them affected will be far more numerous than the number of affected farmed insects, at least in expectation.
10^18 copepods (small crustaceans) according to Tomasik, 2009.
On the other hand, I expect the number of farmed insects to reach on the order of 10^11 to 10^12: 500,000 tonnes in 2030 by dry weight or dried protein meal, and about 0.05 grams per dried black soldier fly larva, but they live around 14 days before slaughter, so I’d estimate the number alive at any time in 2030 to be:
So that’s at least around 1,000,000x more wild arthropods than farmed arthropods. On the other hand, we should expect a greater share of the farmed insects to be affected, possibly a far greater share, and insects should matter more on average and in expectation, but 1,000,000x is a lot.
For example, springtails are estimated to be “100,000 individuals per square meter of ground” (wiki). To match the number of farmed black soldier fly alive at any moment in 2030, you would need to affect 1 million square meters, or 1 square kilometer of soil (in a way that has a modest impact on their population or average welfare). When you scale that down to individual consumption choices, probably less than 1 millionth of this, it doesn’t seem crazy for the springtails to be affected more, and possibly much more, in expectation. If a single farmed salmon is fed 1 kg of dried BSF larva meal*, that’s something like 20,000 individual BSF larvae who would have lived around 14 days each. I think it’s likely that more than 1 square meter of soil (so possibly more than 100,000 springtails per moment) is affected for more than 14 days in expectation for a few kg of other feed for one farmed salmon. So springtails could be affected far more.
*This is probably an overestimate, maybe 10x too high or more. Farmed salmon convert around 1 kg of dry feed into 1 kg of wet weight gained, and have final weights of around 3 to 6 kg, but insects would probably only make up around 5-15% of their feed by weight even for those that do include insects in their diets (similar to current fishmeal inclusion rates), and the vast majority probably still won’t.
Are you suggesting we should prefer to eat fish from species that are already overfished, to make their populations even more depleted and thus reduce the number that are suffering?
If that were the only important effect, maybe, because I’m also suffering-focused. But I’d rather say that I’m clueless about whether eating fish is good or bad. There are also other effects, like on small wild aquatic (and for farmed species, terrestrial) arthropods that could end up dominating and could go the other way, but I haven’t thought enough about them. I think this is a reasonable position whether or not you’re suffering-focused, as long as you’re roughly utilitarian of some kind.
I think even with this line of thinking, the growth of insect farming specifically for use as feed for farmed aquatic animals probably tips this in the direction of “bad”.
(Edited to correct my math and add the example at the bottom.)
That sounds possible to me, but again I feel very unsure and would want to work through some models before deciding. It still seems possible to me that the effects on wild arthropods (aquatic and terrestrial) could outweigh, even vastly outweigh, the effects on farmed insects. It could depend on which arthropods you count, what probabilities you assign to their consciousness and their expected moral weights, though, e.g. mites, springtails and zooplankton might be too unlikely to be conscious or not matter enough overall, but I suspect the number of them affected will be far more numerous than the number of affected farmed insects, at least in expectation.
Globally, there are an estimated
10^17 to 10^19 terrestrial arthropods alive at any moment, according to Tomasik, 2009 and Bar-On, Phillips, and Milo, 2018. Tomasik, 2009 has a breakdown.
10^18 copepods (small crustaceans) according to Tomasik, 2009.
On the other hand, I expect the number of farmed insects to reach on the order of 10^11 to 10^12: 500,000 tonnes in 2030 by dry weight or dried protein meal, and about 0.05 grams per dried black soldier fly larva, but they live around 14 days before slaughter, so I’d estimate the number alive at any time in 2030 to be:
(14 days alive per BSF larva produced) * (1 year/365 days) * (500,000 tonnes of dried BSF larvae produced/year) / (0.05 grams/dried BSF larva produced) = 3.84 * 10^11.
So that’s at least around 1,000,000x more wild arthropods than farmed arthropods. On the other hand, we should expect a greater share of the farmed insects to be affected, possibly a far greater share, and insects should matter more on average and in expectation, but 1,000,000x is a lot.
For example, springtails are estimated to be “100,000 individuals per square meter of ground” (wiki). To match the number of farmed black soldier fly alive at any moment in 2030, you would need to affect 1 million square meters, or 1 square kilometer of soil (in a way that has a modest impact on their population or average welfare). When you scale that down to individual consumption choices, probably less than 1 millionth of this, it doesn’t seem crazy for the springtails to be affected more, and possibly much more, in expectation. If a single farmed salmon is fed 1 kg of dried BSF larva meal*, that’s something like 20,000 individual BSF larvae who would have lived around 14 days each. I think it’s likely that more than 1 square meter of soil (so possibly more than 100,000 springtails per moment) is affected for more than 14 days in expectation for a few kg of other feed for one farmed salmon. So springtails could be affected far more.
*This is probably an overestimate, maybe 10x too high or more. Farmed salmon convert around 1 kg of dry feed into 1 kg of wet weight gained, and have final weights of around 3 to 6 kg, but insects would probably only make up around 5-15% of their feed by weight even for those that do include insects in their diets (similar to current fishmeal inclusion rates), and the vast majority probably still won’t.