Human Problems (from a shark’s viewpoint) 189
extinction. The northwest Atlantic Barndoor population is now thought to
have recovered to 1960s population levels.
The most critically imperiled batoid group is the sawfishes (Pristidae),
also victims of bycatch despite reduced targeted fishing. Sawfishes were
once reasonably common throughout the waters around Mexico, Central
America, western and eastern South America, most of Africa, Madagascar,
the Arabian peninsula, India, Southeast Asia, the Mediterranean, the Phil-
ippines, and New Guinea. At one time, Lake Nicaragua contained a breed-
ing population of Largetooth Sawfish, thought to have been the largest
sawfish population in the world. Commercial exploitation began in 1970,
with 60,000 to 100,000 sawfish caught over a five-year period. By the early
1990s, no more sawfish could be captured. Their capture finally became il-
legal in 2006.
Once found throughout the tropics in coastal areas with nearby riv-
ers, sawfish ranges have shrunk drastically as the number of highly mobile
adults has declined. Australia probably houses the largest populations, fol-
lowed by the lower Amazon river basin and southern Florida. Although lit-
tle directed fishing now occurs for sawfishes, they often become hopelessly
entangled in nets of all types because of their tooth-studded snouts. Such
bycatch remains the major threat to U.S. federally listed species such as
the Largetooth Sawfish, which was once found in the Gulf of Mexico and
ranged up the east coast to New York. Sawfish in the United States now oc-
cur only in extreme south Florida. According to some experts, sawfishes are
arguably the most imperiled marine fishes in the world.
Visitors to the Georgia Aquarium in
Atlanta view one of the two captive
juvenile Whale Sharks there. Sev-
eral countries have protected Whale
Sharks, the world’s largest fish, be-
cause of their great value in the dive
tourism industry. Photo by Zac Wolf,
Wikimedia Commons, http://commons
.wikimedia.org/wiki/File:Male_whale_shark
_at_Georgia_Aquarium.jpg