In this tweet I want to talk about #Seaspiracy. The documentary has gone viral and is causing a lot of reactions. Compared to scientifical research, which is very multidimentional and hard to grasp, the documentary offers an "extreme" view on the issues concerning the ocean.

This is probably why it has gone viral. People need extreme. This, however, usually means neglecting certain facts. And that is true for this documentary as well. Seaspiracy has a lot of misinformation of about the issues concerning the ocean.

The fact that there is a devaluation of the thruth is a serious problem in the society that we're living in today. Because the documentary contains a lot of misinformation I would like to debunk some of the claims made.

First of all, the overall message in the documentary is fairly OK. Climate change is a big problem, pollution is a big problem and overfishing is a big problem. But several claims made in the documentary are misleading and some are 100% false.

1. No more fish in the oceans by 2048.
This is not true, you can just wipe this from your memory and forget you ever heard of it. Back in early 2000, some scientists published a paper where they looked at the historical decline in fish abundance, and they modeled it into the

future. It said that by year this-and-that the ocean would no longer contain any fish. But, a whole bunch of other scientists debunked this because of a lot of wrong assumptions, and the paper was actually retracted.

2. Sustainable fisheries don't have a definition, and they don't exist.
Neither of these claims are true. There is a definiton of sustainable fisheries. One that takes the analogy of a bank, and another that is brought forward by scientists (sustainability yield curve).

According to the UN food and agriculture organization, about 2/3 of our fisheries are managed at a sustainable level.

3. Phytoplankton needs whale poop.
The documentary is saying that phytoplankton is important for the ocean and that is takes a lot of carbondioxide out of the air, which is true. Then it basically claims that the poop from dolphins and whales is what the phytoplankton needs, and

without whales and dolphins the phytoplanktons are going to die and then the ocean is going to die, and ultimately the humans will die. This is absolutely wrong. Phytoplankton needs iron to photosynthesise, and the ocean has iron deficit. BUT, phytoplankton mostly gets their

nutrition including iron from a lot of physical processes in the ocean. Most of the nutritions they get comes from "upwelling", a process where cold and nutritious water comes from the depths. They also get nutrition from the gas exchange between the ocean and the atmosphere, and

from freshwater running into the oceans from rivers and streams. Dolphin and whales doesn't really play an important role for phytoplankton.

4. Sharks in trophic cascades.
It's hotly debated in the scientific community. In the marine food chain, it says that sharks are the top predator and if you remove the sharks you get new top predators consuming too much of the ones below them and you get an unbalanced ecosystem.

There's no real definitive studies showing that sharks play a role in this phenomenom called trophic cascade. Some papers have studied it but most have been refuted. There are a number of papers that refute the claims that reef sharks play an important role in coral reefs.

The thing is that the marine food chains are super complicated. Much more complicated than food chains on land. There are just so many levels an so many animals within each level, so if you get rid of one animal then there is another animal that takes its place.

There has been no simple cases where the exploitation of one leads to the increase of the other and leads to the decrease of the next one, at least in terms of sharks.

5. Fisheries are blamed for everything wrong in the ocean.
Simply not true. I'm not saying that commercial fisheries are the good guys, they definitely have bad sides like bycatch, trawling and habitat destruction, overfishing, and slavery (mostly in illegal fisheries).

So, there are important issues that we need to deal with. Speaks about the great pacific garbage patch and how almost 50% of the plastic in this garbage patch is fishing nets. The documentary then claims that NGO's are not doing anything to tackle fisheries, which is not true.

Another thing in this is that you can't extrapolate what is happening in the great pacific garbage patch to the whole world. If you're looking on a global scale, only 10% of plastic pollution comes from fisheries, e.g. fishing vessels, fishing nets, fishing ropes, etc.

However, 80% comes from land-based resources. So 80% comes from you and me and everybody else that lives on land, it's got nothing to do with fisheries. So if humans would cut our general plastic consumption (plastic straws etc.) it would have a huge impact on the oceans.

6. Turtles are treathened by extinction because of bycatch.
This is not true. Historically, turtle population have declined drastically, but that is because of the historical exploitation of the eggs and the adult females. People would eat the eggs, or eat the females for meat or

for the shell (especially the hawksbill turtle because their shells are so beautiful). So it's through this historical exploitation that led to the major declines in total populations. Today, yes, they are caught as bycatch in fishing nets by commercial fisheries, and this is

messing up their recovery, but this is by no means the main purpose as to why total numbers have declined. A lot of fisheries are trying to reduce their total bycatch. There's a really cool invention called a turtle exclusion device in the nets which is like a little box in the

net that a turtle can escape through. Bycatch is still an issue, but it is not the main reason for the population decline, and fisheries are trying to lower the bycatch.

7. Coral bleaching.
Why this is brought up is beyond my comperehension. This has NOTHING to do with fisheries. It is because of temperature increase and climate change. This is a hugely accepted scientific fact.

I see that I'm missing a claim, so I'll add it below.

8. It takes up to 20kg of fish to make a 1kg salmon.
100% nonsense. The feed factor for salmon is about 1.2, which means that it takes 1.2kg of food to produce 1kg salmon. Salmon is the most efficient animal to produce. This claim will be cut from the documentary by Netflix.