Chesapeake, according to research by Dr.
Robert Orth, Professor of Marine Science at
the Virginia Institute of Marine Science.
GEORGE GRALL, NATIONAL AQUARIUM
Morgan Denney, an aquarist who takes care
of seahorses at the National Aquarium in
Baltimore, said pollution limits for the Bay
created by the U.S. Environmental
Protection Agency in December 2010 will
likely help seahorses, if regional states put
these limits into action by building
improved pollution-control systems.
Populations of these romantic creatures are
in trouble around the world, partly because
of the disappearance of the seagrasses they
depend on for shelter, Dr. Vincent said. This
loss is caused both by pollution and by bottom trawling by fishing boats that clear-cut
the bottom and kill everything in its path,
shrimp and other prey, which they vacuum
up with their long snouts.
“A reduction in nutrient pollution would
help the eelgrass, and the seahorse population would be expected to bounce back as
well,” Denney said, as he fed brine shrimp
to a lined seahorse in a tank.
“We are losing seahorse populations
because of accidental capture in non-selec-
tive fishing gear that just grabs everything,
and because of the loss and damage to their
wild habitats,” said Dr. Vincent. “Seahorses
live in the world’s most important and most
threatened marine habitats, like seagrasses,
mangroves, coral reefs, and estuaries. Those
are all in trouble, and seahorses with them.”
Because they prefer saltier waters, lined sea-
horses tend to remain in the southern half
of the Bay, and even there, they are relative-
ly rare. The Virginia Institute of Marine
Science surveys the Bay every year by drag-
ging a net to sample for fish. In 1,224 trawls
last year, researchers only found 48 lined
seahorses, according to the Virginia Institute
of Marine Science.
Globally, other factors are also causing declines
in seahorses, including the catching of millions of them off Southeast Asia and Africa to
be ground up and sold in Chinese traditional
medicines, according to Dr. Vincent.
About 48 species of seahorses—from sea
dragons to pot-bellied seahorses—inhabit
the world’s oceans and bays, and 20 percent
of these species have been identified by the
International Union for the Conservation of
Nature as endangered or vulnerable.
Dr. John Musick, Emeritus Professor at the
Virginia Institute of Marine Science, said not
enough data have been collected over time to
conclusively determine whether lined seahorses are in decline in the Bay. But he said it
is logical to assume that seahorse numbers
have probably fallen over the decades as the
amount of underwater eelgrass covering the
Bay’s bottom has shrunk.
Seahorses are also often netted for sale as
pets in fish tanks, or dried and sold in
tourist shops. Dr. Vincent said the most significant cause of seahorse deaths, however,
is the shrimp industry, because it employs
both bottom trawling (which catches seahorses and rips up their seagrass homes)
and the removal of mangrove forests
(another seahorse habitat) for shrimp farms.
For this reason, the simplest thing people
can do to save seahorses is to stop eating
shrimp, Dr. Vincent said. Investments to
reduce pollution and restore eelgrass in the
Chesapeake Bay would also help, she said.
The Chesapeake Bay is home to a single
species, the lined seahorse, which is classified as threatened by the the International
Union for the Conservation of Nature.
Lined seahorses get their names from their
zebra-like stripes. They range from Nova
Scotia to Uruguay, grow to about eight
inches in length, live about four years, and
are masters of changing colors to match
“As the grasses decline, those animals that
depend on the grasses for their cover and
their habitat have to decline too,” Dr.
Musick said. “If there is no cover, there is no
place for the seahorses to live.”
More than half of the Chesapeake Bay’s eelgrass has died since the early 1970s.
Nitrogen and phosphorus pollution from
sewage plants, farms, lawns, and other
sources has stimulated algal blooms that
darken the waters, blocking sunlight that
eelgrass needs to grow.
Seahorses are worthy of the public’s attention, Dr. Vincent said, not only because they
are beautiful and fragile, but also because
their reproductive systems are so rare in the
animal kingdom, with the males acting as
the “Mr. Moms” by carrying the developing
embryos and giving birth.
“It would be a terrible tragedy,” Dr. Vincent
said, “if our lack of attention to our oceans and
bays resulted in us losing this most marvelous
of innovations, the male pregnancy.”
The fins of seahorses are tiny, and so they
are easily buffeted by currents. To survive,
seahorses cling to underwater grasses with
their prehensile tails and hide using
chameleon-like skin. They ambush small
Climate change also could be playing a role in
the eelgrass decline, by creating spikes in sum-
mer water temperatures that cook the fragile
submerged plant, which is sensitive to heat
and at the northern edge of its range in the
Tom Pelton is Senior Writer and
Investigative Reporter for the
Chesapeake Bay Foundation.
Read his blog, Bay Daily, at