Kind: captions
Language: en
sharks are turning up at U.S beaches
farther north sooner and staying for
longer ditching their usual Hangouts for
cooler Waters now when white sharks and
other sharks like bulls and tigers are
moving further north it's less
exploratory and more we're going here to
hang out for a while so it's an
incredible change experts say that
historically many sharks are pretty
predictable in their migration patterns
most sharks they have sort of like a set
course and this set pattern of like
where they go when they go once they're
sort of adults they sort of go back and
forth between these places tiger sharks
typically spend the winter and tropical
waters around Florida and the Bahamas
but travel North in the summer seeking
cooler temperatures but these days their
summer vacations are starting sooner
about for every one degrees Celsius
above the long-term average we see
sharks our tiger sharks extending their
movements about about 200 and and 50
miles further north and in off like the
Northeast like off of like New England
they're starting to come there about two
weeks earlier that has been a big change
the water off the U.S Northeastern Coast
has historically been too cold for tiger
sharks to comfortably thrive in the
average sea surface temperature of the
Earth's oceans has increased steadily
about point 14 degrees Fahrenheit per
decade from 1901 to 2020. in the Gulf of
Maine is one of the fastest warming
bodies of water in the world averaging a
record high sea surface temp of 59.9
degrees Fahrenheit in the fall of 2021
more than four degrees more than the
long-term average this temperature shift
might mean tiger sharks that prefer
tropical water temps could start to move
in I think tiger sharks to some degree
can act kind of like a canary in the
coal mine because their movements are so
intertwined with water temperatures but
it's not just tiger sharks that are
affected by changes in water temperature
on the West Coast baby white sharks are
being spotted unusually far north in
areas like Northern Monterey Bay as a
result of a heat wave in 2014 warmer
water temperatures are motivating tiger
and great white sharks as well as bull
sharks to move to different areas for a
couple of reasons one is most sharks are
considered cold-blooded their body
temperature matches that of their
environment if Waters get too warm
they'll seek out cooler spots another
reason is that what sharks eat is moving
as temperatures get too hot for prey to
thrive they move out and their predators
follow
when apex predators like sharks who are
at the top of their food chains move
into an area it directly affects the
prey already living there if you're a
straight bass and you're in an area that
suddenly sharks start coming through
you're probably gonna leave that area or
you're going to change what time of day
you go to those areas to try and avoid
that predator and that can have a huge
impact on an ecosystem so there's
potential that sharks are putting in a
new predation pressure into these
systems that they haven't seen before
and it'll take time for them to adjust
to it as well since 1970 the global
population of oceanic sharks and Rays
has decreased by more than 70 percent a
dramatic decline bringing some species
to the brink of Extinction one study
found overfishing to be the main driver
of the decline and these new Ventures
also put sharks in danger drawing them
away from parts of the ocean that are
protected from fishing and interference
like mining or drilling they'll probably
have to deal with human encounters more
both in terms of humans being scared but
more importantly of them
getting fished or or killed
advertently and inadvertently and as
ocean temperatures continue to Trend
upwards sharks fish the plants the birds
everything that relies on the ocean is
sensitive to those temperature changes
and they all have thresholds these
changes in shark migration tell us that
even small changes in temp can have a
major impact on life in the ocean
and that we're only just starting to see
the effects of those changes and
fluctuations in patterns that are likely
just beginning
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