For all the fish we eat and ships we sail, humans still know very little about the seas that sustain us. We know even less about how climate change is affecting those waters over time.
“We’re about a century behind—both in understanding our impacts as well as protecting the things that need protecting,” said Elizabeth and Lee Ainslie Assistant Professor of Environmental Studies Loren McClenachan, a marine ecologist. She notes that the United States created its first national park on land in the 1870s, but the first marine sanctuary didn’t come until 100 years later.
McClenachan delves into the past to gain insights about the state of our oceans and rivers today. To do this she relies on a range of historical sources: old maps, photos, newspaper articles, restaurant menus, and even the occasional pirate journal.
By studying nautical charts from the 1770s, for example, McClenachan and fellow researchers documented a loss of more than half the coral in the Florida Keys over the past two and a half centuries. She has also used historical records in Maine to chronicle ongoing changes in the fishing industry.
While shifts in marine ecosystems aren’t always clear cut, she says, they usually result from climate change, overfishing, or some combination. The goal is to clarify the scope of those shifts, try to tease out what’s driving them, and find solutions.
McClenachan combs through libraries and archives to find gold mines of ecological detail, talking along the way with locals who often have lots of relevant and revealing information filed away in their heads. At one public library in Key West, it was only after three weeks of back-and-forth with the archivist that he mentioned a box of what turned out to be “absolutely stunning” old fishing photographs, which she used to study changes in the catch.
Above, Key West trophy fish c. 1956, Courtesy of Monroe County Public Library.
Above left and right, 1965–1979 period, Courtesy of Monroe County Public Library.
Above, Key West trophy fish, 2007, Photograph by Loren McClenachan.
“It’s like detective work,” McClenachan said. “You have to be flexible, and almost opportunistic, in terms of what you can study, based on what historical record exists.”
That’s where pirate journals and menus come in. “I’ve done a lot of work on tasty things,” she said with a laugh. “Things that pirates would be interested in eating, for example, like turtles, because there’s a longer-term record of those things based on human interest.”
McClenachan had been interested in both environmental science and history as an undergrad at Middlebury College. While a grad student at the University of Oregon, she attended a workshop that brought together ecologists, historians, and fisheries scientists. That led to the “a-ha moment” when she realized she could combine her interests into the discipline of historical ecology.
Most of her research, she says, is aimed at using long-term trends to inform better management and conservation of marine life—not just for the sake of the ecosystems themselves but also for the people who rely on them.
“In a lot of cases, we’re interested to know: How exceptional is what we’re seeing now?” she said. Historical records such as annotated maps can reveal long-forgotten places, such as turtle nest beaches or coral reefs, where marine ecosystems once thrived. “The loss of that memory inhibits our ability to really understand how these systems worked,” she said.
Certain populations of turtles, birds, and other animals can rebound quickly when conservation and restoration efforts take hold. “In some cases, it’s happening much faster than people would have expected,” McClenachan says. Her research has found that Maine alewife populations, for example, have proliferated quickly after dam removals, reviving historic local fisheries.
But she warns that if climate change and overfishing continue, some vital species, like coral attached to the bottom, may have no way to adjust to shifting ocean ecosystems. And warming water temperatures could cause a mismatch in migration that could leave predators without prey; changes in spawning times could also disrupt the food web, McClenachan said.
More optimistically, McClenachan hopes that the resilience evident in success stories like the reintroduction of alewives to Maine rivers—along with having a sense of the world our ancestors once knew and what we’re in danger of losing—can encourage more ambitious restoration efforts. “That’s one of the reasons that I’m really excited about doing this kind of work,” McClenachan says. “I see that it is possible to turn some of these things around.”
Loren McClenachan in the news
NPR‘s Morning Edition, The Salt, What’s On Your Plate: Old Hawaiian Menus Tell Story Of Local Fish And Their Demise
The Washington Post‘s Health & Science: The reality of ‘Finding Nemo‘s‘ marine life
WNYC Studios‘ Radiolab: Big Fish Stories Getting Littler