I can tell you that as a child (35 years ago) I spent hours in the water observing fish with my goggles, snorkel and fins; to the point that once my mom thought I had drowned because I was no longer moving.As someone who dives both the med and the Atlantic and channel often I dare to say that the difference is huge in the amount of fish you encounter.
They are all very different habitats as well so it Is difficult to draw a direct comparison.
What baseline are we measuring against? The situation how it was a century ago or a decade ago?
Today, you are lucky if you see any fish outside of a maritime natural park.
I was snorkeling on a Greek island with my son 2 years ago and he was super excited because he saw a fish, it made me sad because of where we (humans) have gotten ourselves.
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