If you really want to go down that route then the human race can easily survive without clean air, water, ground or any animal life on this planet. Why would we need any of that? We, at least a few of us, could just as well be living in sealed underground bunkers powered by thermal energy while eating mushrooms all day and recycling our pee and sweat. Doesn't that sound like a lovely future? ;)
>A century ago not much seafish was available in the inlands, yet the European inland population was comparable in numbers to the current population.
They didn't need seafish because they did have enough land for agriculture, many other places, especially insular nation states and Asia in general, did not and do not have that luxury. I also doubt that current European inland population numbers are in any way comparable with the population numbers of a century ago, back in 1900 global population didn't even break 2 billion, now we are at over 7 billion.