The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past.
We need more celebrations like the one we hold today, with more proud families and happy graduates ready to go out and make a positive difference in the world.
Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time.