Ken Schultz's Field Guide to Saltwater Fish - Macaw Pets store

Known by a variety of names, the thresher shark is characterized
by its well-muscled tail, the upper lobe of which is
usually as long as the rest of the body. These sharks use their
tails to herd baitfish into a mass by slapping or thrashing
the water, then stunning or injuring fish before swallowing
them.
Grayish to dark charcoal in color, the thresher shark turns
abruptly white on the belly and may be mottled on the
lower half of the body. The thresher is further identified by
the absence of a keel on the caudal peduncle; by its small,
pointed, and broad-based teeth; and by its comparatively
smooth skin.
Longtail and pelagic threshers have moderate-size eyes,
and the first dorsal fin is set almost directly in the middle of
their backs and far ahead of the beginning of the pelvic fins.
The Atlantic and the Pacific bigeye threshers have much
larger eyes, and the rear margins of the dorsal fins are
located at least as far back as the origin of the pelvic fins.
Threshers are excellent food fish, comparable to mako
and swordfish, and they are outstanding fighters (the longtail
has been known to leap out of the water). Thresher
sharks were more popular than makos off California until
recently and are a relatively rare catch along the U.S.
Atlantic coast, although specimens in the 300- to 600pound
class are the most common size encountered from
New Jersey to Massachusetts.
The largest threshers have come from New Zealand,
where they’ve been boated in excess of 800 pounds.
The all-tackle world record for A. vulpinus is a 767-pound,
3-ounce fish taken off New Zealand in 1983.
Sharks, Thresher
Alopias species
OTHER NAMES
fox shark, longtail thresher,
pelagic thresher, sea fox,
swiveltail, thintail thresher,
thrasher shark.
Distribution. All threshers
are fundamentally pelagic
but will occasionally move
in close to shore. There are
four species, including the
pelagic thresher (A. pelagicus)
and the Pacific bigeye
thresher (A. profundis),
which occur in the northwestern
Pacific, and the
Atlantic bigeye thresher
shark (A. superciliosus),
which occurs in the Atlantic.
The longtail thresher (A.
vulpinus) is cosmopolitan in
temperate and tropical
waters.
Sharks, Thresher 209