- The sizes of certain species of fish that qualify as “newsworthy” have diminished over time, a new study has found.
- The authors scoured English-language newspapers going back to 1869, searching for terms like “massive” and “giant” in mentions of noteworthy fish landings, and compared the reported lengths with the largest specimens on record for that species.
- They found that for some “charismatic megafish,” such as whale sharks and manta rays, the size that qualified as large has declined over time.
- That shifting baseline could pose a problem for conservation efforts because it gives the impression that “there are still a lot of very large fish in the sea,” marine ecologist Isabelle Côté said.
Hyperbolic headlines can be like catnip for newspaper editors. So when a local fisher hauls in what looks like a record-breaking catch, it often makes news. But a recent study has found that the size of some these noteworthy fish has diminished over time, even as reporters continue to tag them with superlatives such as the “largest” and “mammoth.”
“[T]he fact that the media use similar adjectives to describe fish that are increasingly small is worrisome because people’s opinions are often shaped by what they read in the media,” Isabelle Côté, the study’s senior author and a professor of marine ecology at Simon Fraser University in Canada, said in an email.
Scientists have ample evidence that centuries of fishing in the world’s oceans has depleted stocks. And the fish that make it to market are also often smaller than those sold in the past. Côté said she started thinking about how well the media understood these changes when she noticed a photograph of a massive fish in an old newspaper.
“[I]t made me wonder whether journalists were now using the same language to report on fish that were quite a bit smaller,” she said.
That question set her and her colleagues to work scouring the English-language press as far back as the mid-1800s for mentions of catches of standout fish. They used terms such as “monster,” “gigantic” and “whopper” to filter their results. They ended up with more than 260 articles that included a realistic measure of the fish’s size and that also allowed them to determine what kind of fish it was.
Next, the researchers looked at the reported fish lengths in comparison to the largest recorded size of that species.
Broadly, they found that “the relative length of the largest fish worthy of a headline has declined over time,” they write Feb. 15 in the journal PeerJ. That wasn’t too much of a surprise, Côté said, given that they expected to find a “shifting baseline” of what constituted a “newsworthy” specimen. Shifting baseline syndrome refers to our acceptance that the reduced size of something over time — fish stocks, for example, or the individual fish themselves in this case — is actually the norm.
But the analysis also revealed that the declining size trend only held for certain types of fish. Big fish such as whale sharks (Rhincodon typus), manta rays (Mantaobula spp) and ocean sunfish (Mola spp.) frequently enticed reporters into covering their capture. Fishers don’t usually set out to catch these “charismatic megafish,” which also tend to be larger than many other species, Côté said, so just the fact that they’d been landed was interesting.
Between 1869 and 2015, however, the lengths of fish that qualified as “giants” declined. During the study period, the researchers found that charismatic fish that made the newspapers were on average about half the size of the species’ biggest specimen on record. These species also tended to face higher threats of extinction, the analysis showed.
The team did not find a shifting baseline with sport fish. Reported catches of open-ocean, or pelagic, sharks and billfishes, which include marlins and sailfish, were typically described as large when their lengths actually fit that description.
Côté said that was probably because better records of these fish existed, from tournaments, for example, making it easier for reporters to get more accurate information. In fact, the dearth of data available on charismatic species makes it difficult to track the declining sizes of these fish, “not because the trends are not declining but because the data have not been collected,” she said.
“Given that we have lots of evidence for declines of other species (like pelagic sharks),” Côté added, “it’s probably safe to assume that this is the case for most of the charismatic species too.”
The lack of hard numbers, in combination with news reporting on large fish that make headlines, “can generate an impression (especially among people who don’t have first-hand experience of the ocean) that there are still a lot of very large fish in the sea,” she said.
“It then becomes hard to convince those people that there is a problem.”
Banner image of a male whale shark at the Georgia Aquarium in the United States by Zac Wolf via Wikimedia Commons (CC BY-SA 2.5 ).
John Cannon is a Mongabay staff writer based in the Middle East. Find him on Twitter: @johnccannon
Francis, F. T., Howard, B. R., Berchtold, A. E., Branch, T. A., Chaves, L. C., Dunic, J. C., … & Côté, I. M. (2019). Shifting headlines? Size trends of newsworthy fishes. PeerJ, 7, e6395. doi: 10.7717/peerj.6395
Pauly, D. (1995). Anecdotes and the shifting baseline syndrome of fisheries. Trends in Ecology & Evolution, 10(10), 430. doi: 10.1016/S0169-5347(00)89171-5
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