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pelagic thresher shark pictures
Shark Picture Database
Names: Pelagic thresher, thresher
shark, fox shark, whiptail shark.
Short, stocky, cylindrical body. Upper body colouration slate blue or grey.
Ventral colouration pale. Extremely long upper caudal lobe (same length as
body). Eyes large with slitted black pupils and black irises. Snout and mouth
small. Body broadens around gill areas. Distinct crease/concavity above gills.
Pectoral fins long and mildly spatulate. Fins may be slightly dusky.
Maximum recorded size: 365cm. Mature: 250-300cm
The pelagic thresher spends most of its life in oceanic environments far from
shore but approaches seamounts and deeper reef slopes in order to visit cleaning
stations and sometimes to feed.
Wide ranging in tropical and temperate seas. Absent from the Atlantic but
Probably feeds on small schooling fishes and mid-water cephalopods.
Whips with its long tail in order to stun schooling prey then returns and
consumes incapacitated animals.
At cleaning stations the pelagic thresher stalls in mid-water and drops its tail
to signal to cleaner fish to approach.
with one viable offspring in each of its uteruses. Unborn you feed on
unfertilized eggs (oophagy).
The IUCN lists the Pelagic Thresher Shark as 'Vulnerable'. Justification: All
members of genus Alopias, the thresher sharks, are listed as Vulnerable globally
because of their declining populations. These downward trends are the result of
a combination of slow life history characteristics, hence low capacity to
recover from moderate levels of exploitation, and high levels of largely
unmanaged and unreported mortality in target and bycatch fisheries.
The Pelagic Thresher Shark (Alopias pelagicus) is a large, wide-ranging
Indo-Pacific Ocean pelagic shark, apparently highly migratory, with low
fecundity (two pups/litter) and a low (2-4%) annual rate of population increase.
This species is especially vulnerable to fisheries exploitation (target and
by-catch) because its epipelagic habitat occurs within the range of many largely
unregulated and under-reported gillnet and longline fisheries, in which it is
readily caught. Although this species is reportedly relatively common in some
coastal localities, current levels of exploitation in some areas are considered
to be unsustainable. Overall, it is considered highly likely that serious
depletion of the global population has occurred.
Citation: Reardon, M., Márquez, F., Trejo, T. & Clarke, S.C.
2009. Alopias pelagicus. In: IUCN 2013. IUCN Red List of Threatened Species.
Version 2013.2. <www.iucnredlist.org>.
Monad Shoal, Malapascua Island, Philippines.
The common thresher shark Alopias vulpinus is very similar and shares much of
the pelagic thresher's range. It has a proportionately smaller eye, a larger
first dorsal and grows tmuch larger dimensions.
The bigeye thresher shark Alopias superciliosus prefers deeper water and has
larger eyes than the pelagic thresher. Most notably, the bigeye thresher has a
deep horizontal groove above each gill and eye, and a tail that is not as long
as its body.
Reaction to divers:
A shy species that is usually difficult to approach. Divers at thresher shark
cleaning stations may be able to get close by remaining still and initially
avoiding eye contact. Use of rebreathers can be beneficial.
By far the best location to watch pelagic thresher sharks is Monad Shoal off of
Malapascua Island in the Philippines. The thresher dives take place just after
dawn on a deep ledge about 15 minutes from Malapascua.
Divers swim along the reef slope past numerous cleaning stations until they find
one that the threshers are approaching. Then they drop to the sand and wait for
the threshers to get used to their presence. Sometimes the sharks approach
extremely closely but they are never threatening.
Another good location for pelagic thresher encounters is at Elphinstone Reef in
Egypt. The thresher sharks at this location are less guaranteed and they are
often harder to get close to but many divers have had good experiences here.