A14 EZ RE THE WASHINGTON POST.SUNDAY, FEBRUARY 20 , 2022
BY MAX BEARAKwestern cape, south africa
— The tourist, in her sandals,
flower-print shirt and floppy sun
hat, was concentrating on keep-
ing a sure footing. The boulders
on this desolately beautiful
stretch of coastline were jagged
and slippery.
Then, she looked up.
Before her was a breathtaking-
ly grisly scene: six dead seals
lined up in a row, one splayed
open to reveal its inner workings,
bright red blood collecting in
pools and trickling down to the
crashing waves below. A motley
crew of younger women huddled
over the carcasses. But the tour-
ist didn’t seem fazed.
“What a shame,” she said.
“Pardon me for being nosy, but
do you know what’s killing
them?”
Tess Gridley, a scientist who
doesn’t normally study seals but
has taken it upon herself to find
out what’s been killing thou-
sands of the animals along south-
ern Africa’s Atlantic coast over
the past six months, looked be-
tween the tourist and dead seals
in front of her.
“That’s what we’re trying to
figure out,” Gridley said. The
seals were some of more than 50
she has necropsied on the re-
gion’s beaches.
Marine species on the coasts
around Cape Town are facing
multiple crises. A bird flu out-
break last year took out nearly a
fifth of an endangered cormo-
rant population in South Africa.
Local penguin numbers are de-
clining precipitously, in part be-
cause overfishing is depleting
their sources of food. Further
north, in Angola, fish stocks are
plummeting as climate change
rapidly warms the ocean.
But seals? Who cares about
seals? Most fishermen certainly
don’t — the mischievous crea-
tures snack on their catch. And
while they may be cute, they
aren’t endangered, not even
close. Furthermore, seal mortal-
ity is famously high — as much as
40 percent of pups don’t survive.
So who’s to say that the current
die-off is even abnormal?
Gridley, 40, is convinced this is
abnormal, and a mystery worth
solving that has potential impli-
cations reaching far beyond
seals.
“Seals are just gone from
whole areas of coast, and no one
has batted an eye,” she said. “I’m
filling a gap because it seems
nobody else will.”
It is understandable why en-
dangered bird populations get
attention. Bird flu can jump to
mammal populations and, at
worst, turn into a pandemic.
More commonly, it can infect
poultry and ostriches, both of
which factor heavily into the
South African diet and economy.
But Gridley’s leading theory
for what’s killing the seals is also
a toxin that in high concentra-
tions can pose a threat to hu-
mans and their food.
Domoic acid, released in some
algae blooms, is ingested by
plankton and then moves up the
food chain through shellfish and
anchovies and so on. In humans,
it can cause what is called amne-
sic shellfish poisoning, which, as
the name suggests, primarily af-
fects memory, but also balance,
and can be fatal.
Domoic acid poisoning has
been linked in peer-reviewed
studies to sea lion die-offs in
California. In some instances, the
animals were seen stumbling,
bewildered, along coastal roads,
their memory and balance seem-
ingly gone.
“There are huge parallels” be-
tween California and South Afri-
ca, said Frances Gulland, com-
missioner of the U.S. Marine
Mammal Commission. “And
that’s concerning in part because
the economic impacts were mas-
sive in California. When domoic
acid spiked in samples, the whole
shellfish industry shut down for
months.”
In the late 1990s, Gulland and
other researchers faced a similar
mystery to Gridley’s, but public-
ity and public interest in the sea
lion die-off led to a spate of
funding for research that ulti-
mately proved domoic acid’s
treacherous but largely invisible
threat to marine populations. It
also helped describe how warm-
ing waters and increased agricul-
tural runoff led to more harmful
algal blooms.
Through a U.S. government-
funded program called Mussel
Watch, California now regularly
tests ocean water and marine
organisms for domoic acid and
other toxins, and has tied the
legality of seafood harvests and
sales to toxin levels found in
those samples.South Africa lacks that kind of
long-term study, said Grant
Pitcher, a specialist scientist at
the South African government’s
fisheries, forests and environ-
ment department. The capacity
to test for the toxin is also
unavailable in South Africa.
Much of the suspicion that
domoic acid is to blame in South
Africa is based on odd behavior
by South African seals similar to
what was seen in California be-
fore they die, Pitcher said.
“We know the same problem-
atic species producing toxins
predominate here as in Califor-
nia, and the timing of algae
blooms has coincided with the
seals dying,” he said. “As for the
seals dying, we really don’t have
much monitoring or samplingbeyond what Tess is doing.”
Gridley is systematically try-
ing to get to the bottom of South
Africa’s seal die-off, roping in
veterinarians, algae experts and
chemists who donate their spare
time.
Gridley and her husband are
whale and dolphin experts —
Gridley focuses on bioacoustics,
how those animals communicate
— and are largely self-funding
the seal work with the help of
online donations. Gridley’s 77-
year-old father takes quasi-fo-
rensic photos of the dead seals.
Interns lug equipment and label
jars of seal organs preserved in
formaldehyde for testing later
on. She’s largely taught herself
how to cut open a seal, and
brings some of them, kept coolon bags of ice, to her home
outside Cape Town, where
necropsies are easier than
among the boulders.
“My kids are so tired of dead
seals,” she said, wincing. “They
are so over it.”
The die-off began last Septem-
ber. High tides coughed up doz-
ens of dead seals per mile. Even if
many people along the coast
have mixed feelings about seals,
it has been a shocking — and
pungent — event. Concerned citi-
zens eventually found Gridley,
most via social media, where
Gridley’s nonprofit, Sea Search,
is active.
“I walk a lot along the beach
with my dogs,” said Marianne
Franck, 70, a recent retiree. “One
day, I found 40 of the dead seals.
They were on top of each other,
just, like, you know, dumped
there. Oh, the stench! And the
maggots! And the pups who had
survived crying like little lambs.
And all you can do is just say
goodbye.”
A regular Monday morning for
Gridley now includes receiving a
stream of images of dead seals
from vigilant volunteers up and
down the coastline. She might
then go survey one stretch or the
other. Some days there are doz-
ens of carcasses, some fresh,
others picked up by beach clean-
ers and left in wheelbarrows
with plastic bags over their
heads, yet more presumably
swept back into the sea by large
swells.
The particular kind of seal
that’s been dying — the Cape fur
seal — is thought to number
around 2 million. Their large
population contributes to the
lack of urgency in studying them.
Funding around the cormorant
die-off, for instance, has been
easier to come by.
“We’ve been able to do PCR
tests on hundreds of the birds,”
said David Roberts, a clinical
veterinarian at the Southern Af-
rican Foundation for the Conser-
vation of Coastal Birds. The gov-
ernment has also participated
more actively. Thousands of sick
cormorants were euthanized be-
fore they could pass along the flu,
many of them by having their
necks manually broken before
being discarded in garbage bags.
There were days last September
when more than 500 were being
found dead, Roberts said.
“Seals are much harder tohandle. You need a big truck,
multiple people to carry them,
maybe even a stretcher,” he said.
“If the seals had been dying of
bird flu, it would have been
emergency. But we don’t think
that’s the case.”
Proving domoic acid poison-
ing is a particularly difficult
endeavor anywhere, but espe-
cially in South Africa. The acid
disappears from a dead animal
within hours of death, so freshly
dead specimens are essential.
Even with volunteers sending
images, luck plays a huge part in
the process. The acid also causes
the seals to vomit, which can
decrease the presence of the acid
in the stomach, making it harder
to find.
Because there are no testing
facilities in South Africa, Gridley
has planned on sending some of
her preserved samples to Britain
or the United States. Brains and
other organs require permits to
ship internationally because they
are animal parts, but seal feces
can be sent without one. (“Send-
ing poo, well, that’s easy!” she
remarked excitedly.)
The likelihood that one factor
— domoic acid, in this case — is
solely to blame is unlikely. With
climate change and overfishing
dramatically reshaping marine
ecosystems, the answer is almost
always multifactorial.
“We have to be really sure its
domoic acid before we say that
publicly,” said Gridley. “It has the
potential to cause real alarm, so
we’re not rushing to any conclu-
sions.”
Due diligence likely means at
least dozens more necropsies.
It is not just grim work, but it
is hard. On a recent, blazingly hot
morning, Gridley clambered
among the boulders bleached
white by gull droppings toward
two seals lying motionless. One
was just in a deep slumber, and
bolted awake, as if from a dream,
to find an equally shocked hu-
man peering at it.
The other, however, was dead.
Gridley and three interns
dragged it toward the shade of a
boulder, holding it by its fins and
neck skin. They laid it next to five
others.
“Okay, ladies, let’s get system-
atic about this. Lay them out in
order of freshness,” she said,
gravely. And then, knife in hand,
to herself: “Alright Tess, just get
this done.”A mystery inSouth Africa:What’s killingthe seals?Thousands have washed ashore, and a
whale expert is trying to figure out whyPHOTOS BY SAMANTHA REINDERS FOR THE WASHINGTON POSTTess Gridley, near left, and her team of university students —
Nicole Kieswetter, C atherine Nadin and Maguiña Ramilo
Henry — have necropsied dozens of dead seals that have
washed up on South Africa’s beaches in recent months. “Seals
are just gone from whole areas of coast, and no one has batted
an eye,” the whale and dolphin bioacoustics expert said. “I’m
filling a gap because it seems nobody else will.”The Cape fur seal is thought to number around 2 million. The large
population contributes to the lack of urgency in studying them.