Studying fish stocks from the past in order to figure out the future

Scientists know that fishing stocks the world over are at risk, both from changes due to global warming, and due to over-fishing (and there have been many reports and articles predicting dire forecasts for the health of the fishing stock in the world's oceans). However, in a more detailed and back-looking approach, researchers are studying historical records to see what fish stocks were like just hundreds of years ago, and try to use that data to correlate into estimates of what the future will hold. They are getting hold of historical tax records and logs maintained by sailors, and studying them to determine the long-term impact.
The research was carried out by Members of the History of Marine Animals Project (HMAP), and they came out with results detailing the change in fish species over the past few hundred years that shocked them, and about which they believe that the level of public awareness is low (link to article):

The scale of humanity's impact has shocked them. "I was surprised by the magnitude of the depletion of species and its universality around the globe," Dr. Andrew Rosenberg, an HMAP project leader told CNN. "The extent of it was really quite dramatic. We've fundamentally changed ecosystems without realizing that was possible." HMAP research has revealed a picture of a remarkable wealth of life in the seas as recently as 200 years ago, which has now largely been lost.
Before whaling began in the waters to the south of New Zealand around 1800, the population of whales was roughly 30 times higher than today. In the 17th century the waters around southwest England were home to blue whales, as well as large numbers of porpoise, dolphins, and blue and thresher sharks. Around the world the inshore regions of our seas are estimated to have on average held 10 times the amount of life two or three hundred years ago than they do today.

The oceans are a fundamental factor in the continuance of the human species, whether that be due to the effect they have on global climate, or due to the fact that many geographical concentrations of humanity are dependent on sea life as a major source of nutrition. For the fisheries around the world to have lost so much correlates with earlier research from a couple of years back that stipulated the dangerous position that many of the world's fishing stocks are in. We already see this in the restrictions on the amount of fishing allowed in many regions around the Atlantic in order to conserve the fish population.
At the same time, the research also found that there is hope. If scientifically imposed restrictions on fishing are imposed, fish stocks have bounced back, with the example of the regeneration of the North Sea (Atlantic) herring stocks. If Governments have the courage to thwart the short term interests of the commercial fishing industry, then fish stocks (and the larger species such as whales and other larger fish) can come back.