Beware Herring Worms!!!!!!!!!!!!!!!!!!!!!!! 😱😲😳
NATURE
Worms in
Raw Seafood Have Increased 280x, But It's Not Sushi We Should Worry About
CARLY CASSELLA
20 MARCH 2020
Since the 1970s, a parasitic worm that infects
fish, squid, whales, dolphins and sometimes even us has increased globally by
283-fold, according to a new meta analysis.
That's no small amount, and yet because this creature is so tiny
and the oceans so vast, it's somehow evaded our notice until now. Not even the
researchers themselves can figure out why this parasite is "growing like
gangbusters", or what it could possibly mean in the long run.
Known as the "herring worm"
or Anisakis simplex,
this particular parasitic nematode can hide in raw seafood; if mistakenly eaten
by humans, it can cause symptoms similar to a bad case of food poisoning.
Other mammals aren't so lucky. While the fishing industry might be
inconvenienced by a rising tide of Anisakis,
this parasite poses a much bigger threat to cetaceans, such as whales and
dolphins.
Unlike humans, these marine mammals can get stuck with Anisakis for years,
and they don't have seafood processors and sushi chefs around to carefully
clean out their catch.
Aquatic and fishery scientist Chelsea Wood says consumers don't
need to be too worried; she herself continues to eat sushi regularly. Given
that the fishing industry hasn't even noticed this increase in the parasitic
worm, any risk of us ingesting it probably remains quite low. But the same
can't be said for marine mammals.
"It's not often considered that parasites might be the reason
that some marine mammal populations are failing to bounce back," says Wood.
"I hope this study encourages people to look at intestinal
parasites as a potential cap on the population growth of endangered and
threatened marine mammals."
The impact of this rising parasite on
marine mammals is currently unknown, but if the numbers are right, cetaceans
are facing a much greater risk of contracting Anisakis than half a century ago.
Analysing a total of 123 papers, the researchers reveal an
astonishing increase in Anisakis abundance
over a 53 year period from 1962 to 2015. On average, they explain, this means
we have gone from finding less than one worm in every 100 hosts to more than
one worm in every single host caught.
The global scale of this analysis was too great to pin down any
one factor driving this growth, but Wood has a strong suspicion she knows
what's going on.
"My gut is that this is about the improvements we've made in
marine mammal conservation," Wood told ScienceAlert.
"The time frame of our study directly overlaps with when a
bunch of really important marine mammal legislation went into effect like the
Marine Mammal Protection Act in 1972 and the international whaling commission
moratorium on commercial whaling which came in the 1980s."
Strangely enough, however, not all marine mammal parasites are
increasing. The authors found another similar parasite, called Pseudoterranova, which
infects fish, sea lions and other seals, remained relatively stable throughout
the same time period.
Wood says they were expecting it to be the
other way around, given how much seals and sea lions have thrived in recent
years and how much whales have struggled. So maybe Anisakis is
increasing because its life cycle has to pass through fewer hosts. Or perhaps
it has something to do with the fitness of cetaceans versus seals.
The problem is, we have no baseline for what 'natural' looks like.
The rising number of ocean worms could be a sign of the ecosystem thriving, or
they could represent a growing threat to already endangered and vulnerable
creatures like Hector's
dolphin (Cephalorhynchus
hectori).
The only studies available for analysis come from near history,
and by this time, humans had already changed the oceans in drastic ways.
This raises the question: is the abundance of Anisakis increasing
in response to human impacts, like fishing, pollution, or climate change, or is
it recovering alongside an exploited marine mammal host?
Right now, we just can't say for sure. Wood thinks the most
plausible explanation is that some marine mammals are doing well, leading to an
increase in the parasite at the expense of more vulnerable creatures who now
face an increased risk of infection. We simply need more research.
"This is the story of only two
parasite species among millions that are extant, and we encourage others to use
historical ecology approaches to track change across a diversity of marine
parasite species," the authors write.
"Only then will we have the data to indicate whether
contemporary oceans are facing a 'rising tide' of marine disease."
In this case, we completely missed out on the rise of Anisakis, and while it
might not matter to humans this time, some day it very well could.
"There are way bigger infectious disease threats that people
have to worry about, particularly for now," says Wood. The effects
of Anisakis are
pretty mild, she says, and while it's certainly not fun to barf, we've got
bigger fish to fry.
