How an ocean
ecosystem can change following decline of an apex predator
Date: February 13, 2019
Source: University of Miami Rosenstiel School of
Marine & Atmospheric Science
A new study
has documented unexpected consequences following the decline of great white
sharks from an area off South Africa. The study found that the disappearance of
great whites has led to the emergence of sevengill sharks, a top predator from
a different habitat. A living fossil, sevengill sharks closely resemble
relatives from the Jurassic period, unique for having seven gills instead of
the typical five in most other sharks.
These
findings are part of a long-term collaborative study between shark researcher
Neil Hammerschlag from the University of Miami (UM) Rosenstiel School of Marine
and Atmospheric Science, and wildlife naturalist Chris Fallows from Apex Shark
Expeditions.
The research
focused on the waters surrounding Seal Island in False Bay, South Africa, a
site well known for its "flying" great white sharks that breach out
of the water when attacking Cape fur seals. Since the year 2000, the research
team has spent over 8,000 hours observing great whites from boats, during which
they recorded 6,333 shark sightings, and 8,076 attacks on seals. These data
revealed that for more than a decade, great white numbers were relatively
stable, but in 2015 sightings began to drop off steeply.
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