Sharks are especially vulnerable to habitat destruction and fishing
pressure
because they have slow rates of maturation and reproductive turnover.
Sharks
are unusually long lived and give birth to relatively minuscule numbers
of
young when compared to other types of fish. Many species breed only
every
other year and have 13 month gestation periods.
Because sharks have been so efficient as predators and foragers they
are a
phenomenally successful group of animals that have gotten away with
such low
reproductive rates; however, the introduction of modern fishing methods
and
industrial fallout have been devastating to shark populations
world-wide.
Shark populations are slow to recover from over-harvesting and several
U.S.
species are considered threatened or endangered with regional
extinction.
Virtually all historic commercial shark fisheries in the U.S. and
abroad
have ended in the population crash of the species of shark being
targeted.
Historically, commercial shark fisheries have exhibited a boom/bust
cycle of
over-harvest and decline where the fishery invariably ends with an
abrupt
and resounding crash.
While commercial fishing mortality of sharks in U.S. waters has
averaged
20,000 metric tons per year, computer modeling and statistical analysis
indicates that anything above 10-12,000 metric tons will eclipse the
targeted sharks species abilities to reproduce at sustainable rates.
According to National Oceanic Atmospheric Administration (NOAA),
between the
early 1970's and late 1980's the abundance of many of many shark
species
found along the southeast coast of the U.S. has declined as much as 80
percent.
In addition to being directly targeted in various commercial and
recreational fisheries throughout the world, sharks are all too often
captured incidentally as by-catch in tuna and billfish fisheries. Shark
by-catch in large-scale high-seas fisheries around the world could be
as
much as 50% of the reported take of commercial shark fisheries. The
number
of sharks caught annually by various high-seas fisheries between 1989
and
1991 has been estimated at 11.6 to 12.7 million. To this day a
complete
accounting of shark and ray catches is lacking all the while the
fisheries
continue to expand.
In many cases this by-catch is discarded. It is also estimated that
numerous
high-seas commercial fisheries discard more than 210,000 metric tons of
elasmobranches annually.
The oceans of the world are being purged of sharks and large fish. The
demand for shark meat, fins, and cartilage are at an all time high.
World
population of humans is at an all time high and continues to grow.
There has
been little or nothing at all done on the international level. While
the UN
has rendered oversized drift gill-nets illegal there is inadequate
enforcement and a lack of overall judicial fortitude regarding high
seas
poaching and over-harvesting. Some nations have taken steps
independently
but these efforts are often last resorts applied to an already crashing
shark fishery. Local independent grass-roots education and advocacy are
crucial to the efforts of wildlife conservationists and management
officials. Scientific research is crucial to our understanding and
protection of sharks from over exploitation. Many important species,
which
are protected on a local or regional basis, are now understood to be
highly
migratory and therefore exposed to fisheries and poaching pressures
outside
of those relative protected zones. A more comprehensive monitoring and
management plan is needed to address these issues in order to assure
the
future presence of the worlds sharks, the great fishes and sea turtles.