for example your idea on over-fishing. this over-fishing is generally done by the larger fishing companies. local fisheries have incentive to keep the population in check as they cannot just migrate to another fishing area. that means that over generations those locals will have learnt a lot about this very thing. usually bigger business is a bit more careless, as they generally have more options to go to if one is depleted.
That spiecies are declining due to human impact is a bit of a tough conclusion to draw and i'd like to see how specifically this is proven. Not to say that this doesn't happen, but people are often quick to judge eachother and look at human impact on things, all the while spieces have been going extinct and new ones have been rising up from long long before humans were around.
this study and data since 1950, most likely looks at the impact of fisheries on the area. no doubt. but did it look also at the time before fisheries to see what was happening tot the population then? Is there a good baseline made? I'm pretty sure they won't have the same data pre-fisheries and compare the two, but only look at the data they gathered while the fishing was already going on.
Don't take this as an attack on your opinion, i'm a bit skeptical on anything really, and don't disagree that humans ofcourse in areas have negative impact on nature due to their disregard of it. It jjust pains me to see a lot of small local businesses getting hurt because some studies point to them as a source of a problem while often these studies are fairly shallow. even 50 years of data has potential to be a 1-sided data collection, aimed at proving a specific point instead of trying to show data which might prove OR disprove it. (in a lot of these situations it's practically impossible to gather good baseline data to compare to, as human interactions have been present from before the data collection started, i am aware of that.)