Old snapshots document fish populations, curb “shifting baselines syndrome”
Most vacation snapshots spend their days languishing in photo albums, shoeboxes, or hard drives, not really doing anything useful. But thanks to a new field of research called historical marine ecology, some old holiday photos might actually help us understand fisheries.
Loren McClenachan, one such researcher, was recently profiled in Smithsonian Magazine. A graduate student at the Scripps Institution of Oceanography in San Diego, McClenachan scours old newspapers, travel photos, ships' logs, cannery records, and other records to get a sense of fish populations and sizes in previous decades and centuries. A series of snapshots illustrates how fisheries around the Florida Keys have changed in recent decades: the earliest photos show fish large enough to swallow a small child whole, while the most recent photos show fish that could barely threaten a finger.
The historical research of McClenachan and others can help address something called the shifting baselines syndrome. This term was coined by fisheries scientist Daniel Pauly in 1995 to describes the tendency of people to think that the natural world that they have seen in their lifetime is "normal," when in fact the ecosystems are severely degraded and continuing to degrade. Over time, a baseline — like what makes a "good season" for Pacific salmon — can gradually shift, giving us a false perspective and affecting policymaking or individual actions.
As an example, the film "Empty Oceans, Empty Nets" (which aired on PBS a few years ago) included an interview with Linda Greenlaw, swordfish-catching boat captain and author of "The Hungry Ocean." Greenlaw was opposed to swordfish boycotts by chefs and other regulatory proposals because she thought that the oceans were in good shape. After all, she was still catching "big" swordfish and making a decent living. However, a "big" swordfish to her was about 150 pounds. Go back a few decades and you'll find that "big" fish were two or three times heavier (see Carl Safina's "Song for the Swordfish" in Audubon for details). And if a 150-pound swordfish becomes the baseline for current fishery regulators, that promotes the false impression that there are plenty of big fish out in the oceans, therefore possibly delaying regulations. One can imagine a policymaker thinking, "Well, if this professional swordboat captain says that the oceans look healthy to her, maybe we don't need to restrict fishing." This shifting of baselines can continue for generations.
Another example of a shifting baseline was mentioned on KQED's Quest, during a segment about proposed marine protected areas (MPAs) off the coast of California. MPAs are areas in which no fishing will be allowed, essentially offering fish a safe haven, a place where their young can thrive and where fish can survive the nets and hooks long enough to reach breeding age. Protected areas are one of the few bright spots in ocean management — scientists are finding that fish populations and diversity increase rapidly in the protected areas, as well as that the surrounding areas benefit because fish move out of the protected areas to find new feeding and breeding grounds. Quest interviewed a middle-aged commercial fisherman who was opposed to MPAs because he thought that they weren't needed and would be a financial hardship for the industry. He said that the ocean near the San Francisco Bay was the healthiest he'd ever seen it.
That might be true, but how was the ocean's health before the California water project started pumping huge amounts of water from the Delta to the Central Valley and points further south? Or before most of the wetlands on the edges of S.F. Bay were drained or filled? Or before the S.F. Bay Area became heavily urbanized and a huge source of water pollution?
Without accurate baselines from the past, we can't answer those important questions, so it's great to read about researchers like McClenachan using creative approaches to learn about the fisheries of the past.
Photo of men and fish from the Dale M. McDonald Collection of the Florida Keys Public Libraries subject to a Creative Commons License. More photos of fish are in the Florida Keys Public Libaries' "Dead Fish" photo set.
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