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By Phil Colarusso
Thousands of silver fish flashed around my head in every direction. The school of pollock seemed to be everywhere at once and their sheer abundance was disorienting. It’s easy to understand how difficult it must be for a predator to pick out individual fish in this incredible moving mass of life.
I’ve only had the pleasure of being enveloped by large schools of fish a few times in my diving career. Even so, today’s schools are typically small compared to historical accounts of fish abundance. Mariners in the 19th century and earlier reported schools streaming past their boats for hours at a time, so they probably had millions of fish. In 2013, it’s rare to find these massive congregations.
We used to believe the bounty of the seas was endless. We’ve since learned that fish, like other natural resources, are finite. Slow declines in abundance can go undetected by fishermen, scientists and the public. But, if these changes continue over a long time, lower levels of abundance become the new normal state.
Scientists have coined the term “shifting baselines” to describe this phenomenon. Each generation of scientists regards the state of the natural world during their career as the normal state, but in reality, small changes over multiple generations result in dramatic differences. The ocean that I swim in now is a very different place than the ocean of Jacques Cousteau in the 1960s.
The logical question to ask is: “Where did the bounty go?” Unquestionably, a large percentage of it went into fishermen’s nets to feed the world’s growing human population, but that’s not the only thing that’s going on. The oceans are part of a system with a large number of interlocking components involved in an elaborate balancing act. A significant change in one piece inevitably has implications (both positive and negative) for others. For example, in New England, the overfishing of cod resulted in skate and dogfish populations exploding. Simply stopping the fishing of cod may not be sufficient to restore populations to their historic levels: cod fishing ended on the Canadian side of Georges Bank more than a decade ago with little population recovery.
However, while my oceans are different than the oceans of Cousteau, they’re still special places. As I was surrounded by pollock, it was impossible not to be filled with hope.
About the author: Phil Colarusso is a marine biologist in the Coastal and Ocean Protection Section of EPA New England, and is an avid diver. He’s living the dream in Wenham with wife JoAnn, two kids, dog and white picket fence.