Seaspiracy, a filmmaker sets out to document the harm humans do to marine life and uncovers alarming global corruption.

Has this convinced you to stop eating fish?

  • uthredii@lemmy.mlOP
    1·
    4 years ago

    I guess they wanted to show that there are an astronomically large number of plastic particles floating around. Maybe it would be more relevant to say how the current concentration of plastic particles affects sealife but I don’t think this is very well understood at the moment.

    I believe this is the paper they were referencing regarding the pacific bluefin tuna. It states that:

    The ratio of SSB in 2014 relative to the theoretical unfished2SSB (SSB2014/SSBF=0, the depletion ratio) is 2.6%

    Which is what was said in the documentary. I am not an expert so I don’t know the nuances between the IUC data you gave and this data.

    Another misleading claim: If one species go extinct, the population of its pray repidly explodes and consumes the next trophic level until they go extinct, and then starves to extinction. This starts a chain of extinctions. This is not an ecologically realistic scenario

    What part of this is unrealistic?

    • Zalamander@lemmy.ml
      3·
      4 years ago

      Yeah, I get what they mean - that there quantity of micro plastics is very large, and that that is an issue. In order to make that point, they make a claim that sounds quantitative “500 x # of stars in milky way = # of microplastic particles in the ocean”.

      I see it this way. There are 6.022 x 10^23 carbon atoms in 12 g of pure carbon. Since there are about ~ 2 x 10^11 stars in the milky way, I can easily hold 3 trillion times as many carbon atoms as there are stars in the milky way on the palm of my hand! But this is not really an impressive feat.

      Without explaining how a microplastic particle is defined, their statement gives us quite literally no information. So it really is a meaningless statement.

      I am not saying that it is not true that there are a lot of microsplastics, and I am not saying that it is not an issue. What I don’t like is the form of the statement.

      About the tuna, first: they claim that the species is listed as endangered, but it is listed as vulnerable.

      You can see here: https://www.cnbc.com/2019/01/05/tuna-sells-for-record-3-million-in-auction-at-tokyos-new-fish-market.html And here: https://www.deseret.com/2020/1/7/21054116/the-worlds-priciest-tuna-japan-kiyomura-kimura-sushi-endangered

      That they are talking about Pacific Bluefin Tuna. You can also see on the video that it is Pacific Bluefin Tuna. Here you can see that it is listed as vulnerable: https://www.iucnredlist.org/species/170341/65166749 So, that is an outright lie.

      They then show the following graph:

      They are citing data from the organization that you cited above. Here is a more recent report: https://www.wcpfc.int/node/47311

      Their claim in the documentary is very clear: The total population today is 3% of the population in 1970, and that it has been sharply decreasing.

      Even if we put aside the fact that the SSB is not equal to the population, this is not even true for the SSB! The SSB has been increasing since 2011, and it is at 6.4% of the estimated unfished levels last year. You can try comparing the graph that they show with the graphs in the document, and you can easily confirm that they just made up that graph. They are fabricating data, and I don’t think that that is acceptable.

      Now, with regards to the SSB, the SSB is a parameter that does tell you about the health of the population, as it is the amount of individuals of reproductive age that are found in the area. However, you can’t just say that the SSB is equal to the population. The reality is a lot more complicated.

      With regards to the third part:

      How is this different from removing the shark and saying: “Tuna are apex predators”

      ?

      Both predation and food supply play a role in controlling the carrying capacity. While it is possible for an ecological imbalance to result in an extinction, it is not what will generally happen. Population dynamics are complex!