Danger
for the Basking Shark
DNA
Testing Reveals Continued, Illegal Trade In Fins Of Endangered Basking
Sharks
Science Daily — Despite regulations by some countries to protect
the behemoth basking shark from further population declines, a new
study published in the current on-line edition of Animal Conservation
reports that the world’s second largest fish is still being
killed for its high-priced fins.
Growing up to 40 feet long, the filter-feeding basking shark is
considered to be extremely vulnerable to fishing pressure, perhaps
more so than most sharks, because it grows slowly, matures late,
and has low numbers of offspring, resulting in naturally small populations.
Historical commercial fishing for its meat and vitamin-rich liver
oil frequently resulted in rapid collapses of its populations. (Credit:
Sally Sharrock--The Shark Trust)
Scientists from the Guy Harvey Research Institute at Nova Southeastern
University and the Pew Institute for Ocean Science at the University
of Miami, both in Florida, and from England’s Imperial College
and Durham University used a novel, streamlined DNA analysis method
to document the presence of fins from basking sharks in the Hong
Kong and Japanese fin markets, and even in the USA where this species
has been completely protected by fishery regulations since 1997.
“The demand for basking shark fins, which can fetch prices
in excess of $50,000 (USD) for a single large fin, is continuing
to drive the exploitation, surreptitious and otherwise, of this
highly threatened species,” says Mahmood Shivji, Ph.D., director
of the Guy Harvey Research Institute (GHRI), who led the research
group. “This finding, along with our recent research documenting
extremely low genetic diversity in basking sharks worldwide, raises
urgent concerns about the longer-term health of this species.”
Growing up to 40 feet long, the filter-feeding basking shark is
considered to be extremely vulnerable to fishing pressure, perhaps
more so than most sharks, because it grows slowly, matures late,
and has low numbers of offspring, resulting in naturally small populations.
Historical commercial fishing for its meat and vitamin-rich liver
oil frequently resulted in rapid collapses of its populations. Because
of concerns about its vulnerability and downward trajectory of its
stocks, the basking shark is protected from landing and trade by
national legislation in the waters of several countries. It is listed
as “Endangered” by the World Conservation Union (IUCN)
in parts of its range and on Appendix II of CITES (The Convention
on International Trade in Endangered Species).
“Our findings suggest that preventing worldwide collapse of
basking shark populations will require expanded protection for this
vulnerable species and better enforcement of existing fisheries
and trade rules,” says Ellen Pikitch, Ph.D., a co-author and
executive director of the Pew Institute for Ocean Science at the
University of Miami Rosenstiel School of Marine and Atmospheric
Science.
One of the major problems with monitoring the trade in shark products
to prevent exploitation of protected species is the difficulty in
identifying detached body parts and processed products accurately
to species-level. The rapid and low-cost DNA forensics test for
basking sharks developed and used by Shivji and colleagues generates
a simple, DNA fingerprint unique to basking sharks.
“The simple-to-use DNA forensics test developed and used by
the research team should make it more efficient to screen large
numbers of shark products in the trade stream, making detection
of basking shark products and assessment of compliance with national
fisheries and international CITES regulations much easier in the
future,” according to Jennifer Magnussen, the paper’s
lead author and a graduate student at GHRI.
The Guy Harvey Research Institute is a scientific research organization
based in Ft. Lauderdale, Florida, at the Oceanographic Center of
Nova Southeastern University (NSU). GHRI was established in 1999
as a collaboration between the renowned marine artist Dr. Guy Harvey
and NSU’s Oceanographic Center to conduct solution-oriented,
basic and applied scientific research needed for effective conservation,
biodiversity maintenance and understanding of the world’s
wild fishes. For more information, visit http://www.nova.edu/ocean/ghri.
The mission of the Pew Institute for Ocean Science is to advance
ocean conservation through science. Established in 2003 by a generous
multi-year grant from the Pew Charitable Trusts; the Pew Institute
for Ocean Science is a major program of the University of Miami
Rosenstiel School of Marine and Atmospheric Science For more information,
visit http://www.pewoceanscience.org.
Note: This story has been adapted from a news release issued by
Pew Institute for Ocean Science.
Marine
Scientists Monitor Longest Mammal Migration
Science
Daily — Marine scientists recently published a research paper
in the science journal, biology letters, that found humpback whales
migrate over 5,100 miles from Central America to their feeding grounds
off Antarctica; a record distance undertaken by any mammal.
Kristin Rasmussen, a biologist with
Cascadia Research Collective, and lead author in the study, finds
the record-breaking migration interesting, but is most pleased that
the study validates a long held assumption that humpback whales
travel to warm water areas during the winter.
"It was very exciting because for years everyone said humpback
whales could be found in warmer waters during the winter months,
but this was the first time we were actually able to quantify this
on a global scale, and relate it to these long distance migrations"
said Rasmussen.
Researchers conducted the survey by identifying individual humpback
whales on their wintering area off Central America, and then comparing
these with whales identified on their feeding areas off Antarctica.
Identification of individual whales is accomplished by comparing
a unique set of markings on their fluke, like a "fingerprint,"
with a catalog of photographs held by the Antarctic Humpback Whale
Catalog at the College of the Atlantic in Bar Harbor, Maine.
The scientists found some humpbacks traveling from Antarctica across
the equator to as far north as Costa Rica to overwinter, a distance
of approximately 8,300 kilometers or about 5,157 miles. The authors
noticed that the presence of cold water along the equator coincided
with the occurrence of this northerly wintering area, not only in
the eastern Pacific, where the Central American whales were studied,
but also in the eastern Atlantic, where another southern hemisphere
humpback whale population can be found north of the equator during
winter.
Daniel Palacios, an oceanographer working out of NOAA's Southwest
Fisheries Science Center laboratory in Pacific Grove, Calif., correlated
sea-surface temperature with the whale migration by using data collected
from satellites and distributed by the National Oceanographic Data
Center.
"This study was possible thanks to the availability of reliable,
high-resolution sea-surface temperature data collection that cover
even the most remote regions of the globe," said Palacios.
Note: This story has been adapted from a news release issued by
NOAA National Marine Fisheries Service.
Beached whales
back in the swim thanks to new rescue technique
MICHAEL BYRNES
IN HOBART
THE Australian
island of Tasmania, which has more mass whale strandings than anywhere
else in the world, has developed the first technique to successfully
rescue the giant mammals.
The new method, in which nets were positioned under whales with
the help of jet-propulsion powerboats, was used for the first time
last week to free seven of the creatures from a sandbar at Strahan
on Tasmania's rugged west coast.
"It relies on having the right nets, the right boats, and also
there's a risk of entangling the whales in the nets," Rosemary
Gales, who led the rescue, said. "These are potentially quite
dangerous operations."
Sperm whales of up to 50 tonnes are often stranded in Tasmania.
"We get to practise," Ms Gales, who works for Tasmania's
department of primary industries and water, said. "There doesn't
seem to be an equivalent in the northern hemisphere of the real
hot spot we have here in Tassie," she said.
Smaller stranded whales are relatively easy to rescue. But for the
sperm whale giants, jet boats are used to dig holes around the semi-submerged
animals. Nets are then brought in to pull the whales into the holes
and into increased flotation. "It's a power thing, really,"
Ms Gales said. "The jet boats we were using were about 350
horsepower. They can achieve very shallow draft, and there's no
props, so there's no risk of injuring the animal."
In the past, little could be done to save stranded sperm whales.
However, this is the third time the technique has been used successfully
- each of them in Tasmania - and the first time it has been used
on more than one animal.
The victims of single strandings are usually old, sick whales, or
young animals which have made a mistake.
Mass stranding hot spots seem more likely to be caused by the shape
of the sea floor. Tasmania's north-west coast is very tidal, which
can take an animal from safe, deep water to a stranding in a matter
of hours.
Big seas on Tasmania's west coast may also deposit so much material
in the water that it interferes with whales' sonar and echo-locations,
Ms Gales said.
Other theories put forward have blamed the earth's magnetic field
and other magnetic fields created by man-made cables and the like.
Some say noise may affect whale acoustics.
For some species with strong social bonds, when one strands, the
rest follow. Ms Gates said: "Who knows what they're thinking.
Are they stupid or incredibly wonderful?"
GRIM TOLL'S SUDDEN RISE
ABOUT 30 whales are reported stranded in Tasmania each year. At
an average of one every 12 days, this is more than the other two
hot spots, New Zealand and the North Sea. The Western Isles have
the highest number for Scotland, with the Firth of Forth and the
coastal area of Aberdeen second and third.
Accounting for 80 per cent of whale mass strandings in Australia,
Tasmania has been reporting sharply increasing numbers of strandings
since the early 1980s. Nobody knows whether strandings are increasing,
or whether only reports are rising.
According to the latest data, only around five strandings a year
were being reported in Tasmania between the early 1900s, soon after
whaling stopped, and the early 1960s. In the mid-1960s this shot
up to around ten, then rose to 20 in the mid-1980s, and to around
30 from the 1990s on.
Some
Bottlenose Dolphins Don't Coerce Females To Mate
Science Daily — Mating strategies are straightforward in bottlenose
dolphins, or are they? Much of the work carried on male-female relationships
in that species to date show that males tend to coerce females who
are left with little choice about with whom to mate.
Two bottlenose dolphin males butt heads in Doubtful Sound, New Zealand.
(Credit: Susan Maersk Lusseau, 2002)
This explains
the complex relationships we observe in male bottlenose dolphins,
which are only paralleled by human social strategies: the formation
of alliances and alliances of alliances, also called coalitions.
These alliances and coalitions are then used to out-compete other
male bands to access females.
A population of bottlenose dolphins in Fiordland, New Zealand, may
be rewriting the textbooks. In this population males form alliances
and coalitions and have complex social relationships, but they do
not coerce females into mating.
David Lusseau, in a study published this week in PLoS ONE, posits
that the complexity of male social relationships in this population
emerge to compete for female choice. Male coalition formation is
observed during fights in this population. Usually coalition formation
will be driven by short-term gains for the helper (for example access
to females). But there do not appear to be any short-term benefits
in coalition and alliance formation in this population. Instead
one male band seems to spend much more time with sexually receptive
females and females with new calves than others.
Lusseau says: "In a mating system driven by female selection
being able to exclude other males from the vicinity of oestrus females
means that individuals can be more readily picked as a favourite
partner."
The old saying seems to hold true for these dolphins: "far
from the eyes, far from the heart."
Citation: Lusseau D (2007) Why Are Male Social Relationships Complex
in the Doubtful Sound Bottlenose Dolphin Population
Site
Of Human-dolphin Partnership Becomes Protected Area
Science Daily — The government of Myanmar has established
a protected area for, of all things, a partnership between fishermen
and a small, gray beakless dolphin with a knack for herding fish
into nets, according to the Wildlife Conservation Society (WCS).
Specifically, some 70 kilometers of the Ayeyarwady River have been
protected to safeguard the cooperative fishery. It also supports
one third of the river's population of Irrawaddy dolphins, a species
that is threatened throughout much of its coastal and freshwater
range.
Fishermen plying the waters of Myanmar's Ayeyarwady River have formed
a partnership with the waterway's Irrawaddy dolphins, which drive
fish into the waiting nets. (Credit: B. Smith/Wildlife Conservation
Society)
"This
is a big step forward toward saving this cetacean in the Ayeyarwady
River and the fishery that benefits both humans and dolphins,"
said WCS researcher Brian D. Smith, who has conducted research on
the species in the region for several years. "Balancing the
protection of a critically endangered wildlife population with local
livelihoods and preservation of a unique cultural tradition is a
win-win situation for all."
The fascinating partnership involves fishermen summoning the dolphins
to voluntarily herd schools of fish toward the boats and awaiting
nets. With the aid of the river-dwelling dolphins, the fishermen
can increase the size of their catches by threefold, and the dolphins
appear to benefit by more easily preying on the cornered fish in
both nets and on the muddy banks of the river.
The Irrawaddy dolphin grows to some 2 to 2.5 meters in length (6.5
to 8 feet) and frequents the coasts, estuaries, and freshwater lagoons
of Southeast Asia. It is threatened throughout its range by incidental
catches and in several areas by habitat degradation.
The dolphin population in the Ayeyarwady River is one of the most
threatened, specifically by electrocution from illegal electric
fishing and entanglement in gill nets, and from mercury poisoning
and habitat loss from gold mining operations in the river. Recent
surveys of the river conducted by the Department of Fisheries and
WCS found that the species range had declined by some 60 percent,
and that only 59 to 72 individuals remained in a region some 1000
kilometers from the sea. In response to these findings, the World
Conservation Union (IUCN) designated the population as "critically
endangered."
The new protected area will boost awareness about the Irrawaddy
dolphin and its unique role in the river's livelihoods, as well
as enforce the prohibition of electric fishing, gold mining, and
other threats, and initiate a systematic monitoring program for
the species. Another positive development is a recent ban on gold
mining in the Ayeyarwady and a recent survey conducted by WCS and
the Myanmar Department of Fisheries found that the ban had been
100% effective on eliminating this threat from the river.
"If the protected area proves successful at conserving dolphins
and enhancing the livelihoods of local fishermen, it could be used
as a model for extending similar protection to other river segments,"
added U Mya Than Tun, Senior Scientist with the Myanmar Department
of Fisheries.
Note: This story has been adapted from a news release issued by
Wildlife Conservation Society. |
