Earlier this week, deep-sea ecologist, and conservation biologist, Andrew Thaler Tweeted out this strange, and shocking, bit of information
There's a globe-spanning layer of mesopelagic fish that is so dense it distorts SONAR. For decades we had no idea what created the Deep Scattering Layer or why it moved. We still know almost nothing about it.— Andrew Thaler (@DrAndrewThaler) June 21, 2021
It contains 65% of all fish biomass.
Marine Ecology has Dark Fish. https://t.co/2ghU52smax
In that Twitter thread he links to a 2014 phys.org article explaining that 95% of the world’s fish biomass are mesopelagic fish — fish that live between 100 and 1000m below the surface. This is 10-30 times more than previously thought. Fish that live that deep have evolved to have enhanced pressure sensitivity, larger eyes for seeing in the dim light of the deep and, apparently, are much too wily to be captured by fishing nets. This means we haven’t really been eating them, but we also haven’t really been studying them either. They are “Dark Fish,” as it were.
What does this ACTUALLY mean? It means that there are way more UNKNOWN fish living out there in the oceans than we ever thought possible. This is great news! It means that waters previously thought to be “ocean deserts” may actually be sustaining vibrant life deeper down than we can see. It means that the largest fish stock in the oceans isn’t in coastal areas but in the central parts of the oceans. And it means that fishing has not yet touched 95% of fish biomass. The oceans are healthier than previously thought. You love to hear it.
It has been estimated statistically that around 18 species of large marine animals (over 1.8m long) remain undiscovered. Presumably some or all of these are Dark Fish.— Robert Haynes (@RobertHaynes_1) June 21, 2021
The whole thread is fascinating and full of biologist jargon and delightful fish-related science puns
So in order to investigate this, we'll need to build a Large Haddock Collider…— Fully Vaccinated Jon (@JonS253) June 21, 2021
Nothing to see here folks. Move along. Move along.
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