The ocean is really big and its teeming with life.As earlier responses have noted, this is an exceedingly common misperception. It further fails to acknowledge harms done.
Estimates are that upwards of 90% of all marine animal life has been destroyed largely by human activity.
Vast fisheries have utterly collapsed, notably Grand Banks cod off Newfoundland, sardines off California, orange roughy, and more. Surviving fisheries are hugely impacted, often with both far fewer and far smaller individuals than in historical records.
Records and understand themselves are exceptionally limited, as major scientific study of the oceans dates only to the mid-20th century, after which much of the harm had already been done.
A fascinating trivium is that there is more oil floating in tankers over the oceans than there are fish swimming in it.
And, as myshpa noted, the deep oceans tend not to have much biological activity. Fish (and plankton) aggregate near continental boundaries where upwelling provides essential nutrients. Sunshine and water alone are vastly insufficient.
Map of global fisheries / fish stocks: <https://www.theglobaleducationproject.org/earth/fisheries-an...>
State of fisheries: <https://worldoceanreview.com/en/wor-2/fisheries/state-of-fis...>
Notably this map showing sustainable- / over-exploitation status: <https://worldoceanreview.com/en/files/2013/04/wor2_c3a_s52_3...>
