Shifting baselines back 1000 years

The health of most fish populations is measured by the current population size compared to an estimated "unfished" population size. While fisheries biologist recognize that the estimates of the unfished population size is not exact, what if they're off. Waaaaay off.

Scientists at the Oceans Past meeting in Vancouver, Canada report that

...fish stocks were already depleted before the industrial exploitation of the 20th century made the situation even worse. "We used to think that if we could get fish stocks back up to the levels of the 1970s we would be well on the way to recovery," says Holm. This now seems to be an optimistic idea.

The concept of shifting baselines is not a new one. Scientists Jeremy Jackson and Daniel Pauly were early adopters of a term to describe the way significant changes to a system are measured against previous baselines, which themselves may represent significant changes from the original state of the system. Most of our fisheries baselines are from right before industrialized fishing began, leaving us with only about 50 years of irresponsible fishing to recover from.

If humans have been overfishing the oceans for 1000 years, what does this mean for our perceptions of what makes a healthy ocean ecosystem? How does this affect how conservation groups, seafood buyers and individuals act when they talk about or buy seafood? Should our definition of a fishery's recovery change? And is the need for recovery more urgent if overfishing has been happening for a thousand years instead of 50?

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