Shifting Baselines

“Nature has no hope in the absence of history.” Carl Safina in Shifting Baselines: The Past and the Future of Ocean Fisheries

We face a paradoxical bind, needing simultaneously to look backward and move forward. It’s dangerous, warn the editors of “Shifting Baselines: The Past and the Future of Ocean Fisheries,” to “ignore historical change and accept the present as natural.”

First coined in 1995 by marine ecologist Daniel Pauly, the term “shifting baselines” describes a widespread tendency to assess change using too recent a reference point – typically how conditions appeared early in a researcher’s life or career. When that pattern extends across generations, it can lead to a persistent ratcheting down of expectations – coming to accept as “normal” simplified food webs with less diversity and resilience.

Shifting baselines can, for example, prompt us to celebrate a population rebound that looks impressive in the context of a 30-year time span but pales in comparison to the population and range of that species 300 – or 3,000 – years ago.

Lisa Kerr, a fisheries ecologist at Gulf of Maine Research Institute (GMRI) in Portland, acknowledges how hard it can be for marine researchers to find appropriate reference points against which to measure change in fish stocks. Fisheries managers, she says, typically rely on data from 1980 onward. A longer historical context would be valuable, but is not always possible due to limited data.

To glimpse how ecosystems functioned before significant human influence, researchers may have to use archaeological records. Karen Alexander, a historical marine ecologist and one of the editors of “Shifting Baselines,” notes that is particularly true in New England, given its long history of exploiting marine resources. Findings from Native American middens on North Haven, dating back more than 3,000 years, reveal that even those early inhabitants changed the ecosystem.

Today, calculating reference points to gauge change is further complicated by the rapid pace at which ecosystems are transforming in response to climate change. While there’s still value in understanding early historical baselines, Kerr explains, as warmer and more acidic waters alter the productivity and distribution of species, some “may not have the capacity to recover to [their] historical biomasses.” In looking backward, therefore, some researchers now concentrate not just on historical stock levels but on past climate trends – to understand how populations and ecosystems responded during warm years.

“Rate of change” is a concept far too few people understand, Alexander says, particularly in reference to how climate change impacts compound over time – making cumulative effects difficult to address by the time they register. Climate disruptions can upset the “distribution and timing” of many species, she adds, disturbing the coordinated biological activities in complex, interconnected ecosystems.

Marine scientists have traditionally tracked seasonal variations and population cycles. Now, Kerr explains, warming is transforming the ecosystem, prompting a “really active conversation” among scientists and policy-makers about how to best to manage resources in the face of more linear change. “We’re kind of turning [the concept] on its head, asking should we shift our baselines for management” forward – to the recent past, Kerr says, and potentially keep shifting them to reflect the evolving ecosystem when waters warm further.

As climate change intensifies, recent data take on added importance. Tracking physical conditions and ecological populations is more critical than ever as baselines are continually redefined. And yet, there’s been a “huge degradation in our ability to understand the Gulf of Maine” over the past five to ten years, says Andrew Pershing, chief scientist at GMRI, as both the federal government and international bodies have dropped long-term monitoring efforts.

Jeffrey Runge, a GMRI researcher and professor at the University of Maine School of Marine Sciences, has felt a growing sense of frustration watching the abandonment of data sets for plankton extending back more than half a century – losing track of species at the base of a marine food web just when the ecosystem is undergoing dramatic change. He points to the example of the copepod Calanus finmarchicus, a species he describes as “wildly successful across the whole North Atlantic” historically– supporting predators from small fish like herring and mackerel up to cetaceans like the right whale. However, rapidly warming waters in the Gulf of Maine have caused substantial declines in its population here since 2010.

The University of Maine lost funding last year for its Calanus monitoring sites in the Gulf of Maine, even as Canadian researchers were reporting a continuing drop in the Bay of Fundy Calanus population. Right whales that used to feed there had disappeared in recent years, and in 2017 they showed up instead in the Gulf of St. Lawrence, where Calanus still abound. Because the whales were not expected there and no shipping or fishing regulations to protect them were in place, 12 of them died – a devastating loss for an endangered species with fewer than 465 whales left on the planet.

Loss of data does not always lead so directly to loss of life, but managing blindly – without sufficient science to track baselines disrupted by climate change – can put more species and fisheries at risk. Pershing appreciates the pressures facing government agencies with flat budgets, but can’t fathom the choice to abandon long-term data sets that help anchor scientific understanding at a time of accelerating change. These decisions, he fears, “are really going to bite us as we grapple with what this ecosystem will be in the future.”

© Marina Schauffler, 2018. All Rights Reserved. Column reprints available upon request.