Hello Vasco, thank you a lot for your reply. Some food for thought (as I did not extend a full analysis of all being mentioned and shared):
First, I’ll respond to your second comment. As you can see in the numbers, fishing is responsible for more seabird deaths, but less death of mammals. But what I wanted to point out is that this is a more comparable number (and shows a group of animal can indeed suffer more by plastic than fishing or vice-versa) and it only reveals a part of the numbers, as I stated too in my response. As I said from the start: fishing is the single most cause of death in the ocean, if you include all fish, crustacea (if krills are included the numbers, the numbers of lives can be estimated to the quatrillions, as we fish 2.7 million tons of krill per year, and a krill’s weight is 1 gram per average), though we shan’t ignore the huge impact of plastic in the ocean, as the numbers shown can give higher impact to some of the groups of animals versus others.
Secondly, I read your reply from Michael St Jules, though affirming that ‘microplastic ingestion rarely causes mortality in any organism’ can’t be farther from the truth. As an example from what we already debated, this is what led to the seabird numbers (as there are dozens of studies proving that plastic debris is their cause of death, as you had also pointed out). An example of study here: https://www.nature.com/articles/s41598-018-36585-9 .
For fish, the influence of plastic and microplastic causing deaths can be seen in some rare studies, some here:
Important to note that these types of research pose a difficulty, as death because of microplastic ingestion takes a while to study and is not realistic to be done in labs/ aquaria. There are more studies on marine mammals, turtles and seabirds in their natural habitat as these are examined more commonly by WW environmental agencies when reaching the surface/ ashore (and thus the numbers can be better extrapolated) than fish, frankly revealing the massive speciesism in the marine biology/ environmental studies arena. Also, important to note that these studies we both brought above focus on microplastic, and not cover the ingestion of larger plastic litter by fish, which we know can be the cause of deaths by entanglement, filled stomach (starvation) and choking. In short, there is a clear lack of study on fish deaths by consumption of plastic debris in general.
Another fact to point out on the fishing x plastics debate is that if we immediately stop fishing, the alleviation of the impact on marine life will be immediate, and complete. If we stop using plastics today, we would still have to manage the millions of tons of plastic we had already produced, and that are still in the environment. A study shows that if we stop using virgin plastic right now, in 2050 the amount of microplastics in the ocean will more than double by 2050, coming from the existing plastic pollution: https://www.researchgate.net/publication/358446217_Impacts_of_plastic_pollution_in_the_oceans_on_marine_species_biodiversity_and_ecosystems
I am roughly aware of Brian Tomasik’s numbers on fishing as I work to fight against it myself.
Just to be dead clear, I still am in complete alignment with you regarding the impact of fishing x plastics for the ocean’s ecosystem, as a fighter for the end of fishing myself. I just wanted to shed a light on why not to de-prioritise the efforts on fighting plastic pollution for the protection of the ocean.
Thanks for the comprehensive reply! Strongly upvoted.
Secondly, I read your reply from Michael St Jules, though affirming that ‘microplastic ingestion rarely causes mortality in any organism’ can’t be farther from the truth. As an example from what we already debated, this is what led to the seabird numbers (as there are dozens of studies proving that plastic debris is their cause of death, as you had also pointed out). An example of study here: https://www.nature.com/articles/s41598-018-36585-9 .
The statement you quote refers to microplastic ingestion, but the study you link does not contain “microplastic”, so it may be focussing just on larger pieces of plastic:
There is a 20.4% chance of lifetime mortality from ingesting a single debris item, rising to 100% after consuming 93 items. Obstruction of the gastro-intestinal tract is the leading cause of death. Overall, balloons are the highest-risk debris item; 32 times more likely to result in death than ingesting hard plastic.
However, based on the other studies you linked, I agree the statement “microplastic ingestion rarely causes mortality in any organism” was misleading. I was quoting a page from Our World in Data which has meanwhile been modified, and no longer seems to discuss impacts on wildlife. However, they now have a FAQ on microplastics which reflects uncertainty about the effects on mortality, rather than confidence in the absence of effects (emphasis mine):
One challenge of microplastics is that their small size makes them easier to (consciously or not) ingest. Ingestion of microplastics could have detrimental impacts on wildlife health. The small size of these particles make them difficult to track and monitor; evidence on the impacts and behaviour of microplastics are therefore currently very limited.
I have added to the comment replying to Michael the following. “Update on 29 December 2023: Nathalie Gil pointed out some studies have concluded microplastics increase mortality”.
microplastics are debris of 0,5mm or less, so this fits the size with a lot to spare
Nitpick, microplastics have a diameter of less than 5 mm (which makes your point even more valid).
I am roughly aware of Brian Tomasik’s numbers on fishing as I work to fight against it myself.
Besides often having numbers, another common thread of Brian’s posts is that the impact of reducing fishing may be quite unclear due to indirect effects. To illustrate, here is the summary of How Wild-Caught Fishing Affects Wild-Animal Suffering:
Fishing imposes agonizing deaths on 1-3 trillion fish per year, as well as many other marine animals. However, (over)fishing has many other indirect effects on wild-animal suffering. This piece surveys reasons why the harvesting of wild fish might reduce as well as increase the suffering of oceanic creatures. The net impact is extremely unclear. Moreover, the sign of net impact may depend on what kind of fish is eaten—for example, catching big piscivorous fish may reduce zooplankton populations, while catching small zooplanktivorous fish may increase zooplankton populations. If you do buy fish, it’s plausible though not completely clear that unsustainable kinds are best—e.g., overfished species, those caught with bottom trawling, etc. That said, I would probably err on the side of not eating fish, especially because wild-catch fishing may increase the amount of fish farming in the future.
I guess wild animals have net positive lives, although it is quite unclear, so I think we had better minimise fishing and plastic pollution.
Just to be dead clear, I still am in complete alignment with you regarding the impact of fishing x plastics for the ocean’s ecosystem, as a fighter for the end of fishing myself. I just wanted to shed a light on why not to de-prioritise the efforts on fighting plastic pollution for the protection of the ocean.
Makes sense! I have added the following at the top of the post. “Disclaimer: plastic pollution may well kill way more animals besides seabirds and sea mammals. There are 6.20*10^14 wild fish and 1.00*10^20 wild marine arthropods, but only 6.75*10^11 wild mammals”.
Thanks for your reply, Vasco—all clear and comprehensive. I’d only dispute the claim from How Wild-Caught Fishing Affects Wild-Animal Suffering: ‘for example, catching big piscivorous fish may reduce zooplankton populations, while catching small zooplanktivorous fish may increase zooplankton populations.’ - this does not consider the full balance of the trophic chain, and the fact that if you remove big piscivorous fish, you are in fact on the SHORT TERM increasing the population of zooplankton, however, this have many complex effects, one example: the decrease in the Caribbean shark population is met by an increase in its prey, the grouper fish. The expanding grouper population takes parrotfish, normally responsible for clearing coral of algae, in greater numbers. This could explain why algae now dominates many degraded reefs in the Caribbean. It also shows how the systematic elimination of one species—a key link in a complex web of relationships—can destabilize the entire ecosystem. When it comes to wild animals, no impact is so straightforward and isolated as we’d like to measure. This is my pet critic with EA, as the difficulty in measuring the clean direct impact of efforts in wildlife conservation can be hindering funds to these efforts, however, in the larger sense, the strategy to leave the ocean alone to rebalance its ecosystems is about saving all life on Earth—therefore the investment on ocean conservation has strong direct links to Existential Risk—ours and of all life on Earth. Perhaps this is a conversation to another topic/ thread...!!
Hello Vasco, thank you a lot for your reply. Some food for thought (as I did not extend a full analysis of all being mentioned and shared):
First, I’ll respond to your second comment. As you can see in the numbers, fishing is responsible for more seabird deaths, but less death of mammals. But what I wanted to point out is that this is a more comparable number (and shows a group of animal can indeed suffer more by plastic than fishing or vice-versa) and it only reveals a part of the numbers, as I stated too in my response. As I said from the start: fishing is the single most cause of death in the ocean, if you include all fish, crustacea (if krills are included the numbers, the numbers of lives can be estimated to the quatrillions, as we fish 2.7 million tons of krill per year, and a krill’s weight is 1 gram per average), though we shan’t ignore the huge impact of plastic in the ocean, as the numbers shown can give higher impact to some of the groups of animals versus others.
Secondly, I read your reply from Michael St Jules, though affirming that ‘microplastic ingestion rarely causes mortality in any organism’ can’t be farther from the truth. As an example from what we already debated, this is what led to the seabird numbers (as there are dozens of studies proving that plastic debris is their cause of death, as you had also pointed out). An example of study here: https://www.nature.com/articles/s41598-018-36585-9 .
For fish, the influence of plastic and microplastic causing deaths can be seen in some rare studies, some here:
An interesting study with Rainbow Trouts, is that when fish is exposed to MP and a virus, the chances of dying from the virus goes from 20% than up to 80%! Study here: https://www.sciencedirect.com/science/article/abs/pii/S004896972208295X?via%3Dihub
https://iopscience.iop.org/article/10.1088/1755-1315/631/1/012006/pdf#:~:text=The%20microplastics%20can%20have%20a,oxidative%20damage%20and%20abnormal%20behavior. - This brings an analysis of the plankton Daphinia magna you also shared a study from, showing the death effects of a 0,001 millimetre of plastic (microplastics are debris of 0,5mm or less, so this fits the size with a lot to spare) on their death rate (page 5).
Important to note that these types of research pose a difficulty, as death because of microplastic ingestion takes a while to study and is not realistic to be done in labs/ aquaria. There are more studies on marine mammals, turtles and seabirds in their natural habitat as these are examined more commonly by WW environmental agencies when reaching the surface/ ashore (and thus the numbers can be better extrapolated) than fish, frankly revealing the massive speciesism in the marine biology/ environmental studies arena. Also, important to note that these studies we both brought above focus on microplastic, and not cover the ingestion of larger plastic litter by fish, which we know can be the cause of deaths by entanglement, filled stomach (starvation) and choking. In short, there is a clear lack of study on fish deaths by consumption of plastic debris in general.
Another fact to point out on the fishing x plastics debate is that if we immediately stop fishing, the alleviation of the impact on marine life will be immediate, and complete. If we stop using plastics today, we would still have to manage the millions of tons of plastic we had already produced, and that are still in the environment. A study shows that if we stop using virgin plastic right now, in 2050 the amount of microplastics in the ocean will more than double by 2050, coming from the existing plastic pollution: https://www.researchgate.net/publication/358446217_Impacts_of_plastic_pollution_in_the_oceans_on_marine_species_biodiversity_and_ecosystems
I am roughly aware of Brian Tomasik’s numbers on fishing as I work to fight against it myself.
Just to be dead clear, I still am in complete alignment with you regarding the impact of fishing x plastics for the ocean’s ecosystem, as a fighter for the end of fishing myself. I just wanted to shed a light on why not to de-prioritise the efforts on fighting plastic pollution for the protection of the ocean.
Thanks for sharing and for the debate.
Thanks for the comprehensive reply! Strongly upvoted.
The statement you quote refers to microplastic ingestion, but the study you link does not contain “microplastic”, so it may be focussing just on larger pieces of plastic:
However, based on the other studies you linked, I agree the statement “microplastic ingestion rarely causes mortality in any organism” was misleading. I was quoting a page from Our World in Data which has meanwhile been modified, and no longer seems to discuss impacts on wildlife. However, they now have a FAQ on microplastics which reflects uncertainty about the effects on mortality, rather than confidence in the absence of effects (emphasis mine):
I have added to the comment replying to Michael the following. “Update on 29 December 2023: Nathalie Gil pointed out some studies have concluded microplastics increase mortality”.
Nitpick, microplastics have a diameter of less than 5 mm (which makes your point even more valid).
Besides often having numbers, another common thread of Brian’s posts is that the impact of reducing fishing may be quite unclear due to indirect effects. To illustrate, here is the summary of How Wild-Caught Fishing Affects Wild-Animal Suffering:
I guess wild animals have net positive lives, although it is quite unclear, so I think we had better minimise fishing and plastic pollution.
Makes sense! I have added the following at the top of the post. “Disclaimer: plastic pollution may well kill way more animals besides seabirds and sea mammals. There are 6.20*10^14 wild fish and 1.00*10^20 wild marine arthropods, but only 6.75*10^11 wild mammals”.
Thanks for your reply, Vasco—all clear and comprehensive. I’d only dispute the claim from How Wild-Caught Fishing Affects Wild-Animal Suffering: ‘for example, catching big piscivorous fish may reduce zooplankton populations, while catching small zooplanktivorous fish may increase zooplankton populations.’ - this does not consider the full balance of the trophic chain, and the fact that if you remove big piscivorous fish, you are in fact on the SHORT TERM increasing the population of zooplankton, however, this have many complex effects, one example: the decrease in the Caribbean shark population is met by an increase in its prey, the grouper fish. The expanding grouper population takes parrotfish, normally responsible for clearing coral of algae, in greater numbers. This could explain why algae now dominates many degraded reefs in the Caribbean. It also shows how the systematic elimination of one species—a key link in a complex web of relationships—can destabilize the entire ecosystem. When it comes to wild animals, no impact is so straightforward and isolated as we’d like to measure. This is my pet critic with EA, as the difficulty in measuring the clean direct impact of efforts in wildlife conservation can be hindering funds to these efforts, however, in the larger sense, the strategy to leave the ocean alone to rebalance its ecosystems is about saving all life on Earth—therefore the investment on ocean conservation has strong direct links to Existential Risk—ours and of all life on Earth. Perhaps this is a conversation to another topic/ thread...!!