Historically, that oil had commercial uses, helping drive directed fisheries around Norway, Iceland, and Greenland. The 2019 review reports that targeted fisheries declined during the twentieth century as demand for liver oil fell. Today, most Greenland sharks caught in commercial operations are taken incidentally rather than in major directed fisheries.
The shift reduced one form of pressure.
It did not remove human risk.
Longlines set for Greenland halibut can catch Greenland sharks.
Trawls can catch them.
Gillnets can catch them.
Large sharks may become badly entangled.
Some die before release.
Others may suffer injuries that make their survival uncertain.
NOAA identifies bycatch reduction as a key conservation need.
For a species with such late maturity, even low levels of unintended mortality deserve attention.
Historical fishing may still matter today
A fast-reproducing fish population can sometimes recover noticeably within a few years if fishing pressure falls.
Greenland sharks may operate on a different timescale.
If large mature females were removed heavily in the early twentieth century, some of the animals that would replace them might only recently have become reproductive.
That possibility makes population recovery extraordinarily difficult to measure.
The 2019 management review specifically warns that the species' slow life history likely means recovery from population impacts will also be slow.
This creates a disturbing conservation problem.
Humans can damage such a population quickly.
Nature may need centuries to reverse the damage.
Our political and management systems rarely plan on that scale.
A century is short in Greenland shark conservation
Governments often set environmental goals for five years, ten years, or perhaps several decades.
For a female shark that may not mature until roughly 150 years old, even a fifty-year conservation program represents only part of one generation.
That means success cannot always be judged by rapid population growth.
Researchers may have to look for other signs.
Reduced bycatch.
Improved survival.
Healthy distribution.
Presence of juvenile size classes.
Protection of possible nursery areas.
Continued survival of large adults.
Conservation becomes an act of trust in biological processes that may unfold more slowly than anyone managing them will live to see.
We still do not know where many of them are born
For an animal with such a famous lifespan, basic reproductive geography remains poorly known.
Scientists do not yet have a complete map of mating areas, pupping grounds, and nursery habitat.
Researchers have proposed expanded tagging and survey programs to find these critical places.
That knowledge could change conservation.
If pregnant females gather in particular regions, those places may need special protection.
If juveniles occupy certain fjords or deep-water areas, fisheries could be modified there.
The problem is that Greenland sharks do not make such information easy to obtain.
A pregnancy may be rare to encounter.
A mature female may be older than the scientists handling her by a century.
Every captured animal therefore becomes an unusual opportunity to learn.
Reproduction may contain surprises still waiting to be discovered
The classic published observation of a pregnant Greenland shark involved ten near-term pups, each roughly several dozen centimeters long. Researchers have also observed females carrying hundreds of large ovarian eggs, creating questions about how many eggs are actually fertilized and how reproductive development proceeds.
Scientists believe Greenland sharks give birth to live young rather than laying external egg cases, but many reproductive details remain unresolved.
Gestation length is particularly intriguing.
Other deep-water sharks can have remarkably long pregnancies.
If Greenland shark metabolism stretches reproduction in the same way it stretches growth, gestation may prove lengthy as well.
For now, that remains a question rather than a fact.
The correct response to missing data is not to invent a dramatic number.
It is to recognize how much of the shark's life still lies outside scientific observation.
The shark's flesh carries another Arctic adaptation
Sharks must balance salts and water inside their bodies differently from bony fish.
Compounds including urea and trimethylamine oxide, or TMAO, play important roles in that balance and in stabilizing proteins.
Greenland shark flesh has long been considered unsafe or unpleasant when eaten fresh in significant quantities. Traditional preparation in Iceland involves prolonged processing and fermentation to produce hákarl.
Scientific reviews discuss TMAO and its breakdown products as part of the explanation for historical reports of illness after consuming raw Greenland shark.
This detail has little to do with lifespan directly.
It does show how completely the shark is adapted to an environment that would challenge familiar vertebrates.
Cold water.
High pressure.
Unusual chemistry.
Slow metabolism.
Long life.
None of these traits exists alone.
The Arctic is not a frozen museum
It might be tempting to imagine Greenland sharks living in a world that barely changes.
The opposite is becoming increasingly true.
The Arctic is warming rapidly.
Sea ice is changing.
Ocean temperatures and currents are shifting.
Prey distributions are changing.
Human vessel traffic and fishing patterns can move into areas once difficult to access.
A species adapted to slow biological change may now face fast environmental change.
The 2019 conservation review identifies climate change, fisheries, vessel activity, pollution, and other human pressures as concerns for Greenland sharks.
This creates one of the strangest mismatches in modern ecology.
A shark can take more than a century to mature.
Its environment can change noticeably within a decade.
Evolution gave the shark an exceptionally slow clock.
Humans are speeding up the world around it.
Long life is not always an advantage
Extreme longevity sounds like biological power.
It can also create vulnerability.
If an animal lives for centuries because natural adult mortality is normally low, its population may not be built to replace large numbers of adults quickly.
A new source of mortality can therefore have an outsized effect.
Fishing is the clearest example.
An animal that would naturally survive for another hundred years can be removed in a few minutes by a net.
The shark's adaptations to cold, pressure, starvation, and aging offer no protection against industrial fishing gear.
Evolution prepared it for the Arctic.
Evolution did not prepare it for steel cable.
The oldest animals may be especially valuable
Large female sharks are likely to be among the oldest.
They may also be the animals most important for reproduction.
That combination creates a conservation concern sometimes seen in other long-lived marine species.
The individuals most impressive to humans may also be the individuals a population can least afford to lose.
A five-meter Greenland shark could represent several centuries of survival.
Its body has endured climate shifts, changes in prey, parasites, injuries, and countless winters.
If it is a mature female, it may also carry the reproductive future of a population that replaces adults extraordinarily slowly.
Size therefore becomes more than spectacle.
It becomes time made visible.
The 2016 study changed how scientists looked at every large shark
Before the eye-lens work, researchers already suspected extreme longevity.
After the paper, every large Greenland shark carried a new question.
How old is this individual?
A four-meter shark may be older than any person alive.
A five-meter shark may predate modern industrial society.
The animals look almost unchanged from one encounter to another.
The age is invisible.
Nothing on the skin says 120 years or 350 years.
That invisibility is part of the fascination.
We are accustomed to age changing appearance.
Human bodies visibly age over decades.
Greenland sharks often already look ancient when they are young by their own standards.
Their rough skin, cloudy eyes, scars, and slow movement encourage us to read age into appearance even when we cannot know it.
The lens provides something appearance cannot.
Evidence.
The age estimate also changed the meaning of a scar
Imagine seeing a long scar on a Greenland shark.
When did it happen?
Last year?
Twenty years ago?
A century ago?