In 1969, the CSS Hudson left Nova Scotia and voyaged out into open ocean. The research vessel was embarking on the first complete circumnavigation of the Americas. Along the journey, the Hudson made frequent stops so scientists on board could collect samples and take measurements, with special interest in microscopic plankton.
One of their largest discoveries, now known as the Sheldon spectrum, was a mathematical rule: The abundance of an organism is linked to its size. So, the smaller the organism, the more of them you find in the ocean. “Krill are a billion times smaller than tuna, for example, but they are also a billion times more abundant.”
With overfishing, humans have broken this fundamental law of the ocean. Research shows that the Sheldon spectrum no longer holds true for larger marine creatures. Humans are removing so many fish from the ocean that their populations cannot recover. Thus Sheldon’s spectrum has been disrupted and indicates larger interruptions in the marine food web and ocean ecosystem.