You hypotetical proposal is imposible.
First: Like many have signaled the relation predator/pray would reach a balance sooner or later.
second: even if you take out all the predators, and the fish population increase dramatically, the enviroment wouldnt sufice to feed that many living creatures. (this has already been seen in secluded islands were there is only herbivores with no predators like that japanese rabbit island).
third: Eventually they all die before reaching what you propose, the bigger species just die giving way to smaller living things to come around untill they also evolve and die perpetuating the cicle of bullshit.
fourth: This kind of ideas are ingeneered by the actual culture that has made humanity (and industrial and tecnological progress) as a monster that is destroying the planet, is a culture of self hate. The fact is: industry as we know it, has less than 200 years, 90% of species roaming the earth disapeared on their own wayyy before industrial age. The idea that we are cousing so much "damage" is quite unrealistic (we are doing it but it doesnt mean what people think it means). The extintion of a species involve the rise of another, for example: Yeah, cities eliminate the habitat of deer, and boars, and some birds (All we like to eath, ironic isnt it?), frogs, bees, etc. but: Cockroaches are thriving, you will never find as many roaches in a forest like you find in the normal drain of a regular house... How about pidgeons? there is a lot of them, and rats? nothing like a good old fat 1kg new york sewer rat. The problem is not "we are killing the animals and insects" is that the ones that are thriving in the enviroment we created, we dont like them.
The sea will be fine, even if there is no fishes on it, some algae, bacteria, and non edible (probably toxic) stuff will take the fishes place and they will thrive on the toxic contaminated waters, there is already a bacteria that feeds on plastic...
Sorry I got all weird, happens every now and then, and I wont check this word diarreah, so sorry for the mistakes.