The science of sustainable seafood, explained

Some thoughts on WWF’s Living Planet Report

The conservation world was abuzz last week with the release of World Wildlife Fund’s (WFF) Living Planet Report, a documentation of how humans have impacted Earth’s other living creatures. The report covers all aspects of planetary change with a particular focus on biodiversity loss and habitat degradation. It provides a good, albeit sobering, summary of the state of Nature and wildlife and calls for a global push to strengthen the Convention on Biodiversity (a multilateral treaty between most of the world’s countries) to conserve as much as we can by 2050. We recommend reading the report, or at least the executive summary, here.

Overwhelmingly, this is an important document that we hope leads to more and better conservation measures that protect our planet; however, there are a few issues we had with the report we think are worth pointing out in order to strengthen the policy process and focus.

The press release and characterization of data

It is disappointing when organizations poorly explain the science behind the flashy numbers highlighted in the press release. WWF made a poor choice in their characterization of the decline of species. The big number in the Living Planet Report is that 60% of animal populations have declined since 1970. However, the way that the public understands a ‘population’ is different than scientists. Indeed, that is a staggering figure that needs to be addressed, but a population decline is different than saying, “Humanity has wiped out 60% of animals since 1970” as The Guardian did. Ed Yong at the Atlantic covered the explanation behind that number well:

Ultimately, they found that from 1970 to 2014, the size of vertebrate populations has declined by 60 percent on average. That is absolutely not the same as saying that humans have culled 60 percent of animals—a distinction that the report’s technical supplement explicitly states. “It is not a census of all wildlife but reports how wildlife populations have changed in size,” the authors write.

To understand the distinction, imagine you have three populations: 5,000 lions, 500 tigers, and 50 bears. Four decades later, you have just 4,500 lions, 100 tigers, and five bears (oh my). Those three populations have declined by 10 percent, 80 percent, and 90 percent, respectively—which means an average decline of 60 percent. But the total number of actual animals has gone down from 5,550 to 4,605, which is a decline of just 17 percent.

This needs to be explained in the press release! When science is misleading in the press, anti-science groups get ammunition to push a bad narrative and erode public trust in science. The ‘Global Warming Pause’ is a good example of this.

Further, the incredibly frustrating myth that all fish will be gone by 2048 was started by a press release (in fact, fisheries have a tremendous potential to be much larger and sustainable by then). Science and conservation need to be more explanatory with their public communications.

Fishing false equivalence

The Living Planet Report does a great job covering the scale of degradation humans have caused. Humans have transformed Earth’s land to build cities, pave roads, develop infrastructure, grow food, and raise livestock—WWF estimates around 75% of total land is degraded or threatened by humans. The scale of the Anthropocene is truly remarkable.

This terrestrial transformation has caused species extinction rates not seen since the last asteroid and is mostly responsible for the population declines cited above. The biggest threat to biodiversity on land is further human encroachment on wild spaces. As Earth’s population continues to rise, solutions will need to protect nature, but also allow for humans to live a dignified life, e.g. increased urbanization.

The ocean is different, though. The biggest threat to biodiversity in the ocean is excess carbon dioxide in the atmosphere causing global warming and ocean acidification. In terrestrial ecosystems, primary productivity (the first stage in any food web) comes from land, which humans directly threaten, while in the ocean, primary productivity comes from photosynthesizing plankton, which are not directly impacted by humans (i.e. fished) but are threatened by climate change. Coral reefs and kelp forests, two of the largest and most important oceanic habitats, are also mainly disappearing because of climate change.

WWF does an admirable job addressing climate threats to biodiversity in their report, but their coverage of fishing fallaciously makes a false equivalence to terrestrial impacts. They begin their coverage of fishing by stating that, “Almost 6 billion tonnes of fish and invertebrates have been extracted from the world’s oceans since 1950” with no mention that fish reproduce differently than creatures on land and most fish consumed today are sustainably caught, i.e. renewable! We catch fish to eat, but those fish are replaced the next year. On land, once you clear a forest, it takes centuries to get to the same kind of biodiversity that was once there.

This is a major reason we, along with several other resource-based organizations, advocate that eating fish in place of other animal protein is good for the planet. Compared to terrestrial livestock, fish have no land-use, no fresh water use, no fertilizer runoff, often lower carbon emissions, have fewer habitat impacts, and are renewable. Highlighting the ‘6 billion tonnes’ number is another poor communication choice by WWF.

Fishing data

WWF hyped 60% of population declines, but did not go into any specificity with fish. Here is some relevant information: for the fish populations where we have good data (a little over half of world fish catch), abundance declined on average 38% between 1970 and 2016; however, populations are trending up thanks to improved management. For the other half of world fisheries, we don’t have good data to estimate the amount of decline, but these are largely unmanaged fisheries and most scientists believe the decline has been worse.

Costello et al. 2012 estimated a 10-20% decline between 1979 and 2009 for the large unassessed fisheries of the world.

These estimates are only for the exploited populations of the ocean—most fish species and most biomass in the ocean are not fished; there is no reason to believe there has been any major decline of those populations due to direct human impacts. Indeed, Christensen et al. 2014 estimate that while high trophic level predatory fish have declined by two-thirds in the last 100 years, their prey have doubled; and since there are far more prey fish in the ocean than predators, the total number of fish (and biomass) could be higher now than 100 years ago.

It may also be worth pointing out that only one marine fish has gone extinct. It was a small endemic species wiped out by an El Niño event.

The report also includes in-depth coverage of Global Fishing Watch and the ‘footprint’ of fishing. The paper they cite used low-resolution data that dramatically overestimated the footprint of fishing. Ed Yong at the Atlantic wrote about that paper and its controversy as well.

Surprisingly, the report has no mention of offshore oil drilling. Not only does oil drilling contribute to climate change, but it has a huge capacity to decimate wildlife e.g. The Exxon Valdez and Deepwater Horizon oil spills. Oil companies are the biggest threat to the ocean.

In sum: WWF’s Living Planet report has great potential to be a valuable policy tool going forward. We hope it leads to widespread terrestrial protections and progressive development policies that enable people to live dignified lives alongside nature. We wish it had a better press release and covered the ocean in a different way.

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