19th-century atlas offers glimpse of North Sea's fish-rich past

O.T. Olsen's gorgeous 'Piscatorial Atlas' (1883) describes a world now destroyed and forgotten

Late-19th-century North Sea habitat of the herring.

Image: Wellcome Collection. Public domain.
  • In little more than a century, fish stocks in the North Sea have declined by 99%.
  • For people living today, a grey and exhausted sea is all they know.
  • O.T. Olsen's Atlas of the North Sea's fish species is a reminder of the richness that once was.

"Specialist and magnificent"

In red, an oyster bank the size of Wales, between the Dogger Bank and the coast of northern Netherlands.

In red, an oyster bank the size of Wales, between the Dogger Bank and the coast of northern Netherlands.

Image: Wellcome Collection. Public domain.

Ole T. Olsen's 'Piscatorial Atlas' is a masterclass in data presentation, and it doesn't half look bad either. As map guru Tim Bryars says: "The late nineteenth century was the heyday of the thematic atlas, but I have rarely seen one quite so specialist or as magnificent."

But the atlas does more than be clever and look cool. It's also a window into a world that's now destroyed and forgotten: one in which the North Sea – the body of water between the British east coast and the European mainland – teemed with life. Published in 1883, the atlas devotes one map each to 40-odd species of fish and crustaceans, describing their habits and habitats, and how and when to catch them. Less than a century and a half later, all are now greatly reduced, and some are functionally extinct in the North Sea.

Shifting baselines

\u200bEach map legend details when the species spawns, when and how they can be caught, what they eat, how much they weight, and what their qualities are. Anchovy, for example, is "excellent for sauce".

Each map legend details when the species spawns, when and how they can be caught, what they eat, how much they weigh, and what their qualities are. Anchovy, for example, is "excellent for sauce".

Image: Wellcome Collection. Public domain.

We think of our environment as 'normal', but that's because we don't know any better – by definition, we weren't around to experience the 'normal' from before we were born. This phenomenon is called Shifting Baseline Syndrome, and it's no coincidence that this psychological term has found wide currency in fishery science. Because only SBS and the 'generational blindness' it implies can explain how the virtual extinction of global fish stocks over the past century took place with such little notice.

Consider for a moment the North Sea's waters – grey and soupy today, as everyone thinks they've always been. But thronging its seabeds were once so many oysters, each of which can filter up to 200 litres of water each day, that the sea must have been a lot clearer, as well as healthier for other marine species.

The North Sea's native European oysters (Ostrea edulis) have been a prized delicacy for millennia. They were shipped in quantity all the way to Rome, and tasty enough to be mentioned by Pliny the Elder and Juvenal. In more recent centuries, they were the street food of the urban poor. Back in the 1850s, half a billion oysters were sold each year at Billingsgate fish market in London, harvested from the oyster beds that ringed Britain and Ireland.

Loss of biodiversity

\u201cThe conger is very voracious, will attack man in the water, is very prolific, and its youg furnish a great amount of food for other fish. It is also used for isinglass.\u201d

"The conger is very voracious, will attack man in the water, is very prolific, and its young furnish a great amount of food for other fish. It is also used for isinglass (a gelatin obtained from fish, used in making jellies, glue, etc. and for fining real ale - Ed)."

Image: Wellcome Collection. Public domain.

In particular, Olsen's atlas shows one giant oyster area bigger than Wales, hemmed in by the Dogger bank and the northern coast of the Netherlands. That patch is now gone. As it turned out, Olsen composed his atlas jut before industrial fishing would start to decimate the marine species of the North Sea.

By the end of the 19th century, the oyster catch started to dwindle, due to overfishing and pollution. By the 1970s, the Pacific rock oyster had to be introduced into the North Sea to satisfy demand. By the 1980s, the European oyster had all but vanished. Heroic efforts are being made to bring back the native oyster, but current stocks are barely 5% of what they were 200 years ago.

Compounding the loss of the oysters themselves is the loss of the reefs they build: these help regulate marine ecosystems, build a habitat for biodiversity – by providing food, nursery grounds and refuge for many fish species. Many of those reefs were destroyed by industrial trawling, which has proved equally devastating for other marine species in the North Sea.

94% decline

\u200bThe mackerel was thinly spread across the North Sea, and more numerous to the west, in the Irish Sea and in the Bristol and English Channels.

The mackerel was thinly spread across the North Sea, and more numerous to the west, in the Irish Sea and in the Bristol and English Channels.

Image: Wellcome Collection. Public domain.

Between 1889 and 2007, a statistical study of historical fish catch data shows, fish landings from bottom trawl catches in England and Wales declined by a jaw-dropping 94%. In other words: the modern fish stock in the North Sea is just one-seventeenth the size it was in the late Victorian era. That implies "an extraordinary decline in (…) fish and a profound reorganization of seabed ecosystems", the study says. No prizes if you guess what caused the decline: more than a century of industrialised trawling.

This figure applies to so-called 'demersal' (or bottom-dwelling) species like cod, plaice, haddock and halibut. In particular, haddock had fallen to less than 1% of its former volume, halibut to one-fifth of 1%. Another study suggests that the current biomass of large fish in the North Sea is up to 99.2% lower than if no fishing had occurred.

Bottom-trawling is the main method of catching bottom-living fish today. First attested in the 14th century, the process was industrialised from the late 19th century, first with the advent steam trawlers, and greatly expanded in the 20th century. Already in 1885, the UK government examined claims that industrialised fishing depleted stocks and damaged habitats. But conservation efforts came to nothing, among others by the absence of hard data.

Common Fisheries Policy

\u200bShrimp fishing grounds all hug the coast - but are largely absent from the Norwegian and Danish coasts.

Shrimp fishing grounds all hug the coast - but are largely absent from the Norwegian and Danish coasts.

Image: Wellcome Collection. Public domain.

In fact, the increasingly effective methods of industrial fishing have masked the negative effects they have had on fish stocks. According to the study cited above, the recent history of fishery in England and Wales can be divided into four phases:

  • From 1889 to the onset of WWI: the fishery fleet is converted from sail to steam. Fishing is rapidly industrialised and intensified. Stocks start to decline, but this is compensated by massive expansion of the catch areas.
  • The interbellum (1919-1939): In a second wave of expansion, fishing vessels go as far away as the Arctic and West Africa, managing to increase catches until the late 1950s.
  • From the end of WWII to the early 1980s: fast-declining fish stocks in the North Sea and beyond. As a protective measure, Iceland and other countries declare Exclusive Economic Zones of 50, then 200 miles.
  • From 1983: the UK (and Ireland) join the European Economic Community, and must adhere to the Common Fisheries Policy.

The CFP is a compromise, forcing EU member states to adhere to fish quotas in order to allow the stocks to recover from overfishing. However, it is estimated that quotas have always been up to 35% higher than the levels advised by scientists as sustainable. In order to minimise displeasure of the fishing industry, the CFP has prioritised maintaining catch levels over maintaining stock levels.

Fighting over a comb

\u200b"Very wholesome, nutritious and savoury," the herring is "as pleasing to the eye as the taste is grateful to the palate. It is also food for all fish."

"Very wholesome, nutritious and savoury," the herring is "as pleasing to the eye as the taste is grateful to the palate. It is also food for all fish."

Image: Wellcome Collection. Public domain.

As a result, it is estimated that stocks of demersal fish in the North Sea have declined by 42% since the early 1980s. "In many cases, today's fisheries are sustained by populations of species that should be considered commercially extinct," says the study. The end of the line has been a long time coming:

  • In 1889, Britain's sail-powered fishing fleet landed twice as many fish as today's highly sophisticated vessels.
  • In 1910, British fishermen landed four times as many fish as they do today.
  • The peak year for North Sea fishing was 1938, when 5.4 times more fish were landed in the UK than today.
  • Mackerel fishing ceased in the 1970s due to overfishing. The same could soon happen for herring, cod and plaice.

For the Leave campaign in Britain's 2016 Brexit referendum, the British fishing industry and its perceived suffering at the hands of EU bureaucracy was a major issue. Brexit meant 'taking back control' of British waters and the fish that swim in them, doing away with the limiting quotas imposed by Brussels.

But the baseline has shifted; the piscatorial richness that informed Olsen's atlas and which once filled the North Sea has gone. And duelling with the European Union over those dwindling fish stocks feels a bit like what Borges said about the absurdity of the Falklands War: "a fight between two bald men over a comb."

See every page of Olsen's 'Piscatorial Atlas' in great detail here at the Wellcome Collection.

Strange Maps #1021

Got a strange map? Let me know at strangemaps@gmail.com.

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Reactive oxygen species (ROS) accumulate in the gut of sleep-deprived fruit flies, one (left), seven (center) and ten (right) days without sleep.

Image source: Vaccaro et al, 2020/Harvard Medical School
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An unexpected culprit

The new research examines the mechanisms at play in sleep-deprived fruit flies and in mice — long-term sleep-deprivation experiments with humans are considered ethically iffy.

What the scientists found is that death from sleep deprivation is always preceded by a buildup of Reactive Oxygen Species (ROS) in the gut. These are not, as their name implies, living organisms. ROS are reactive molecules that are part of the immune system's response to invading microbes, and recent research suggests they're paradoxically key players in normal cell signal transduction and cell cycling as well. However, having an excess of ROS leads to oxidative stress, which is linked to "macromolecular damage and is implicated in various disease states such as atherosclerosis, diabetes, cancer, neurodegeneration, and aging." To prevent this, cellular defenses typically maintain a balance between ROS production and removal.

"We took an unbiased approach and searched throughout the body for indicators of damage from sleep deprivation," says senior study author Dragana Rogulja, admitting, "We were surprised to find it was the gut that plays a key role in causing death." The accumulation occurred in both sleep-deprived fruit flies and mice.

"Even more surprising," Rogulja recalls, "we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies." Fruit flies given any of 11 antioxidant compounds — including melatonin, lipoic acid and NAD — that neutralize ROS buildups remained active and lived a normal length of time in spite of sleep deprivation. (The researchers note that these antioxidants did not extend the lifespans of non-sleep deprived control subjects.)

fly with thought bubble that says "What? I'm awake!"

Image source: Tomasz Klejdysz/Shutterstock/Big Think

The experiments

The study's tests were managed by co-first authors Alexandra Vaccaro and Yosef Kaplan Dor, both research fellows at HMS.

You may wonder how you compel a fruit fly to sleep, or for that matter, how you keep one awake. The researchers ascertained that fruit flies doze off in response to being shaken, and thus were the control subjects induced to snooze in their individual, warmed tubes. Each subject occupied its own 29 °C (84F) tube.

For their sleepless cohort, fruit flies were genetically manipulated to express a heat-sensitive protein in specific neurons. These neurons are known to suppress sleep, and did so — the fruit flies' activity levels, or lack thereof, were tracked using infrared beams.

Starting at Day 10 of sleep deprivation, fruit flies began dying, with all of them dead by Day 20. Control flies lived up to 40 days.

The scientists sought out markers that would indicate cell damage in their sleepless subjects. They saw no difference in brain tissue and elsewhere between the well-rested and sleep-deprived fruit flies, with the exception of one fruit fly.

However, in the guts of sleep-deprived fruit flies was a massive accumulation of ROS, which peaked around Day 10. Says Vaccaro, "We found that sleep-deprived flies were dying at the same pace, every time, and when we looked at markers of cell damage and death, the one tissue that really stood out was the gut." She adds, "I remember when we did the first experiment, you could immediately tell under the microscope that there was a striking difference. That almost never happens in lab research."

The experiments were repeated with mice who were gently kept awake for five days. Again, ROS built up over time in their small and large intestines but nowhere else.

As noted above, the administering of antioxidants alleviated the effect of the ROS buildup. In addition, flies that were modified to overproduce gut antioxidant enzymes were found to be immune to the damaging effects of sleep deprivation.

The research leaves some important questions unanswered. Says Kaplan Dor, "We still don't know why sleep loss causes ROS accumulation in the gut, and why this is lethal." He hypothesizes, "Sleep deprivation could directly affect the gut, but the trigger may also originate in the brain. Similarly, death could be due to damage in the gut or because high levels of ROS have systemic effects, or some combination of these."

The HMS researchers are now investigating the chemical pathways by which sleep-deprivation triggers the ROS buildup, and the means by which the ROS wreak cell havoc.

"We need to understand the biology of how sleep deprivation damages the body so that we can find ways to prevent this harm," says Rogulja.

Referring to the value of this study to humans, she notes,"So many of us are chronically sleep deprived. Even if we know staying up late every night is bad, we still do it. We believe we've identified a central issue that, when eliminated, allows for survival without sleep, at least in fruit flies."

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