98 Sharks: The Animal Answer Guide
are still sharks with low reproduction rates (see chapter 6). Some dogfish
stocks have been fished down as much as 95%, leading to restricted catches
and a “Do Right by Dogfish” campaign to reduce overexploitation.
Some other abundant sharks include Blue, Silky (Carcharhinus falci-
formis), School or Tope, and Gummy (Mustelus antarcticus) sharks—all of
which are targets of major fisheries. Among batoids, Bat and Cownose rays
occur in schools of thousands and even millions of individuals (see “Do
sharks form schools?” in chapter 4). Spotted Ratfish may be the most abun-
dant chimaera, with an estimated 200 million in Washington State’s Puget
Sound, an area of about 2,600 km^2 (1,000 square miles). That’s roughly
77,000 ratfish per square kilometer, or about one ratfish every 10 m^2
(equivalent to an area of 30 by 30 ft).
It’s hard to say what the rarest shark, skate, ray, or chimaera might be.
The rarer species are certain small sharks and rays that are endemics (con-
fined to a very small geographic region). Many elasmobranchs are threat-
ened from overfishing and have declined greatly in numbers (see chapter
10). Sawfishes as a group are among the most depleted because they live
near shores and in estuaries, habitats that put them in contact with people.
Even when they are not targeted by fisheries, their saw can become entan-
gled in any kind of net, and they drown or are killed so that someone can
claim the saw as a trophy (even though possession of one is illegal).
Some of the least known sharks, such as small deepwater species, may
or may not be rare; we don’t know for sure because they are difficult to
capture or live in places that are poorly explored or hard to get to. These
include some surprisingly large species, such as the Goblin Shark, which
can grow to 3.3 m (11 ft) long and weigh 159 kg (350 lb); fewer than 50
specimens are housed in museum collections. Among rare large sharks, the
5.5-m-long (18-ft) Megamouth Shark gets the most attention because it
wasn’t discovered until 1976 and, as of 2012, only 54 individuals have been
seen.
Several sharks are known from only one or a few specimens that are
housed in museum collections. The Irrawaddy River Shark, a carcharhi-
nid, is known from a single museum specimen that was caught in the late
1890s at the mouth of the Irrawaddy River in Myanmar. A close relative,
the Northern River Shark, may have a total global population of only 250
mature individuals. The Pondicherry Shark (Carcharhinus hemiodon) of In-
dia is known from only 20 specimens and hasn’t been seen since 1979. Hap-
loblepharus kistnasamyi is a rare shark known only from three adult speci-
mens, all collected from a small area near Durban, South Africa. Among
skates, the Pita Skate (Okamejei pita) is also known from only a single female
specimen collected in 1992 from the northernmost corner of the Persian/
Arabian Gulf. The Ornate Sleeper Ray is known from two museum speci-
http://www.ebook3000.com