the first graph is completely useless, how can you distinguish between all these similar shades of light blue?
That still doesn't cut it: there are 18 fish in the graph key but at first glance the graph has around half that number. The others can be seen if you zoom right in but it's still not easy to hover over the pixel-wide slivers of similar blue.
That said I don't think the tonnage details are the point of this graph but rather a more general message: "Tuna fishing increased 6-fold over 65 years, skipjack makes up most of the increase". I think it communicates this message well. Perhaps more "infographic" than "graph"?