The basking shark is a species of shark found in between
the coast and pelagic zone, or area close neither to
the shore nor the floor of the ocean, of waters ranging
from boreal to warm-temperate. They are most likely
to be found around continental shelves, and it is not
uncommon to see a basking shark near land, such as in
bays. Basking sharks migrate seasonally, plunging to
waters about 3,000 feet deep in the winter.
The length of the basking shark's gestation period
is not known with certainty, it is believed to last
for over a year, and perhaps for even two or three years.
Mating is believed to occur every two to four years
in the early summer, and females give birth to a small
number of live pups in the late summer. The basking
shark reaches sexual maturity between the ages of six
and 13 years, and is believed to live for about 50 years.
The basking shark is the second-largest extant species
of fish, outstripped in size only by the whale shark.
On average, the basking shark measures about 20 to 26
feet in length and weighs about 5.2 tons. The largest
accurately measured basking shark, however, measured
46.4 to 58.1 feet in length and an enormous 19 tons
in weight. Some basking sharks may still measure over
30 feet in length, though large-scale fishing has made
them rare.
Despite what its size may lead one to think, basking
sharks are not dangerous predators. In fact, they are
passive filter-feeders, subsisting on plankton and small
fish and invertebrates. The basking shark is notable
for its enormous jaw, typically measuring about three
feet in width, which allows it to open its mouth very
wide and filter up to 1,800 tons of water per hour.
It typically feeds at or close to the surface of the
water.
Likely on account of its size, the basking shark has
few natural predators. Orcas, or killer whales, have
been observed feeding on basking sharks, though no other
animals seem to pose a threat to the basking shark.
Great white sharks may, however, scavenge on the remains
of deceased basking sharks. Lamprey eels may attach
themselves to basking sharks, but they are unlikely
to be able to harm the sharks due to the basking shark's
thick skin.
Though the basking shark faces few natural threats,
humans pose a danger to it. Fisheries have long favored
the basking shark because of its slow motion, docile
nature, and previous abundance, a fact that likely contributed
to the major decline that the basking shark's population
has suffered in numbers. In the past, the basking shark's
presence along the Canadian Pacific coast was considered
a nuisance, and the basking shark was subject to eradication
efforts by the government in that area.
The basking shark has been issued a conservation status
of vulnerable, an issue to which many countries have
responded positively. A major way in which this has
occurred is through the protection of basking sharks
in territorial waters and the restriction of basking
shark product trade by various countries. An effort
to locate any basking sharks that may still live along
the Canadian Pacific coast and follow their recovery
is also being made.
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