NEWSLETTER
3/2010 14. March 2010
NEW
PARTNERS:
Shark
Specialist Group (IUCN) (Homepage)
Maldives
Whale Shark Research Programme (MWSRP) (Homepage)
Dr.
Richard Pillans, CSIRO Marine and Atmospheric Research, Brisbane,
Australia
Umberto
Scacco, I.C.R.A.M (Istituto Centrale per la Ricerca scientifica e
tecnologica Applicata al Mare) Roma, Italy
Dr.
David Rowat, Chairman, Marine Conservation Society, Victoria,
Seychelles (Homepage)
Dr.
Giuseppe Notarbartolo di Sciara, Honorary President, Tethys
Research Institute, Milano, Italy (Homepage)
Feodor
Litvinov, Atlantic Scientific Research Institute of Marine
Fisheries and Oceanography, Kaliningrad, Russia
Dr.
Jenny Ovenden, Molecular Fisheries Laboratory, St. Lucia,
Australia (Homepage)
Partner
in Google-Maps
LAST
UPDATES:
27.02.2010:
197 new data, 235 new analysed papers
14.03.2010: 241 new data, 248 new analysed papers
NEXT
UPDATE:
Sunday,
28. March 2010
STATISTIC:
Currently
this database contains 6.937 papers (4.524 about recent sharks, rays
and chimaeras, 2.413 about fossil sharks, rays and chimaeras). Out of
this 6.937 papers, 3.088 papers had been evaluated , and there is the
possibility of free downloading 706 papers.
MEETINGS:
ICES
Annual Science Conference 2010
20-24 September
Nantes,
France
Session E:
Elasmobranch Fisheries: Developments in stock
assessment, technical mitigation and management
measures
http://www.ices.dk/iceswork/asc/2010/ThemeSessions/Session%20E%20synopsis%20final.pdf
http://www.ices.dk/iceswork/asc/2010/themesessions.asp
All
abstracts
must be received on or before Thursday 15 April 2010
Early
registration opens March 2010
Early
registration deadline Tuesday 31 August 2010
The II
Colombian Meeting on Chondrichthyans
16-20
August 2010
Cali
(Colombia)
The
deadline for abstracts is May 14, 2010.
Further information
on the Meeting is on the SQUALUS FOUNDATION website
(www.squalus.org).
NEW
PAPERS:
FOSSIL:
BECKER, M.A. &
WELLNER, R.W. & MALLERY, C.S. & CHAMBERLAIN, J.A. (2010);
Chondrichthyans from the Lower Ferron Sandstone Member of the Mancos
Shale (upper Cretaceous: Middle Turonian) of Emery and Carbon
Counties, Utah, USA.; Journal of Paleontology, 84 (2): 248-266
LANE, J.A. (2010);
Morphology of the Braincase in the Cretaceous Hybodont Shark Tribodus
limae (Chondrichthyes: Elasmobranchii), Based on CT Scanning.;
American Museum Novitates, 3681: 1-70
WHITENACK, L.B. &
GOTTFRIED, M.D. (2010); A Morphometric Approach for Addressing
Tooth-Based Species Delimitation in Fossil Mako Sharks, Isurus
(Elasmobranchii: Lamniformes).; Journal of Vertebrate Paleontology,
30 (1): 17-25
VISAGGI, C.C. &
GODFREY, S.J. (2010); Variation in Composition and Abundance of
Miocene Shark Teeth from Calvert Cliffs, Maryland.; Journal of
Vertebrate Paleontology, 30 (1): 26-35
SHIMADA, K. &
EVERHART, M.J. & DECKER, R. & DECKER, P.D. (2010); A new
skeletal remain of the durophagous shark, Ptychodus mortoni, from the
Upper Cretaceous of North America: an indication of gigantic body
size.; Cretaceous Research, 31 (2): 249-254
RECENT:
PÉREZ-JIMÉNEZ,
J.C. & SOSA-NISHIZAKI, O. (2010); Determining reproductive
parameters for population assessments of two smoothhounds (Mustelus
californicus and Mustelus lunulatus) from the northern Gulf of
California, Mexico.; Bulletin of Marine Science, 86 (1): 1-11
BALLANTYNE, J.S. &
ROBINSON, J.W. (2010); Freshwater elasmobranchs: a review of their
physiology and biochemistry.; Journal of Comparative Physiology B:
Biochemical, Systemic, and Environmental Physiology, xxx: 19p
STEVENS, J.D. &
BRADFORD, R.W. & WEST, G.J. (2010); Satellite tagging of blue
sharks (Prionace glauca) and other pelagic sharks oV eastern
Australia: depth behaviour, temperature experience and movements.;
Marine Biology, 157 (3): 575-591
McCOMB, D.M. &
FRANK, T.M. & HUETER, R.E. & KAJIURA, S.M. (2010); Temporal
Resolution and Spectral Sensitivity of the Visual System of Three
Coastal Shark Species from Different Light Environments.;
Physiological and Biochemical Zoology, 83 (2): 299-307
FELDHEIM, K.A. &
CHAPMAN, D.D. & SIMPFENDORFER, C.A. & RICHARDS, V.P. &
SHIVJI, M.S. & WILEY, T.R. & POULAKIS, G.R. & CARLSON,
J.K. & ENG, R. & SAGARESE, S. (2010); Genetic tools to
support the conservation of the endangered smalltooth sawfish,
Pristis pectinata.; Conservation Genetics Resources. In Press.
FELDHEIM, K.A. &
CHAPMAN, D.D. & SWEET, D. & FITZPATRICK, S. & PRODOHL,
P.A. & SHIVJI, M.S. & SNOWDEN, B. (2010); Shark virgin birth
produces multiple, viable offspring.; Journal of Heredity. In Press.
SCACCO, U. & LA
MESA, G. & VACCHI, M. (2010); Body morphometrics, swimming
diversity and niche in demersal sharks: a comparative case study from
the Mediterranean Sea.; Scientia Marina, 74 (1): 37-51
CONRATH, C.L. &
MUSICK, J.A. (2010); Residency, space use and movement patterns of
juvenile sandbar sharks (Carcharhinus plumbeus) within a Virginia
summer nursery area.; Marine and Freshwater Research, 61 (2): 223-235
OVENDEN, J.R. &
MORGAN, J.A.T. & KASHIWAGI, T. & BRODERICK, D. & SALINI,
J. (2010); Towards better management of Australia’s shark
fishery: genetic analyses reveal unexpected ratios of cryptic
blacktip species Carcharhinus tilstoni and C. limbatus.; Marine and
Freshwater Research, 61 (2): 253-262
VIGNON, M. &
SASAL, P. & JOHNSON, R.L. & GALZIN, R. (2010); Impact of
shark-feeding tourism on surrounding fish populations off Moorea
Island (French Polynesia).; Marine and Freshwater Research, 61 (2):
163-169
MØLLER, P.R. &
NIELSEN, J.G. & KNUDSEN, S.W. & POULSEN, J.Y. & SÜNKSEN,
K. & JØRGENSEN, O.A. (2010); A checklist of the fish fauna
of Greenland waters.; Zootaxa, 2378: 1-84
MISCELLANEOUS
Category: Paleontology
• Sharks
Posted
on: February 22, 2010 7:49 AM, by Brian
Switek
A
restoration of the giant, durophagous shark Ptychodus,
courtesy paleo-artist Matt Celeskey.
The study of prehistoric sharks is
no easy task. Specialists in other branches of vertebrate
paleontology at least have the reasonable hope of discovering
complete skeletons of their subjects; except in instances of
exceptional preservation the scientists who study sharks typically
only have teeth and a few vertebrae to work with. Still, you can
tell a lot about a shark by its teeth, and a new study published in
Cretaceous Research suggests that one peculiar form was a
shell-crushing giant.
Thanks to Jaws,
"Shark Week", and other sensationalist films the word
"shark" most immediately conjures up images of streamlined
predators with triangular, razor-sharp teeth. For much of the public
the great white shark (Carcharodon
carcharias) is the
epitome of "sharkiness", but there is a much wider variety
of shark types. The largest fish in the sea, the whale shark
(Rhincodon
typus) is a filter
feeder with teeth smaller than your fingernails, while the much
smaller Port Jackson shark (Heterodontus
portusjacksoni) has
differentiated teeth adapted for crushing mollusks. And, just like
today, there was a diversity of shark types in the past. One of the
most enigmatic was the Late Cretaceous form Ptychodus
mortoni.
The
largest tooth recovered for the new Ptychodus mortoni
specimen. (From Shimada et al., 2010)
Like many other kinds of
prehistoric sharks Ptychodus
is primarily known from bits and pieces. A tooth here, a vertebrae
there, but altogether the scraps add up. In fact, last
year a team led by Kenshu Shimada used what was known about the
shark to suggest that it was enormous, perhaps in excess of 11
meters in length, and the new paper builds upon this hypothesis.
The new specimen comes from
Jewell Country, Kansas, and is little more than a portion of the
upper jaw associated with a total of 19 teeth. Smack in the middle
of the continental United States the county is about as land-locked
as it is possible to get, but in the time of Ptychodus
(about 89 million years ago) there was a great sea that stretched
from Canada down to the modern Gulf of Mexico. This was the Western
Interior Seaway, the home of plesiosaurs, mosasaurs, and, of
course, enormous sharks.
Four
views of the jaws of two species of Ptychodus.
A) Lower jaw of Ptychodus
decurrens as viewed from
above, B) Upper tooth plate of Ptychodus
occidentalis as viewed
from below, C) Lower jaw of Ptychodus
occidentalis as viewed
from above, D) Lower jaw of Ptychodus
occidentalis as viewed
from below. (From Shimada
et al., 2009)
But the teeth of Ptychodus
did not look very much like those of its living relatives. The
largest tooth from the jaw fragment, measuring 33.5 by 41 mm, looks
like a flat garbage-can lid. It is not a tooth for stabbing or
slicing but for crushing, as were the rest of the recovered teeth.
In life these would have been arrayed in a set of opposing plates
in the upper and lower jaws containing about 500 teeth each; vast,
knobbly surfaces perfect for crushing large clam-like organisms and
barnacles. This made Ptychodus a "durophage", or
an organism that primarily consumed hard-shelled prey.
An
outline of the upper jaw of Ptychodus mortoni showing the
position of the new fragment, and a comparison of the size of the
shark next to an adult human. (From Shimada et al., 2010)
But what did Ptychodus
look like? Several interpretations have been put forward. Some
think that it had a flattened body like a stingray, while others
have suggested that it had a more streamlined shark shape. The
authors behind the new study split the difference by suggesting
that it was something like a nurse shark (Ginglymostoma
cirratum), a shark
well-adapted to cruising over the bottom in search of hard-shelled
prey to consume.
Ptychodus
would have been much larger than any nurse shark, though. Based
upon the fragments of the upper and lower jaws recently recovered
and what is known about the relationship between jaw size and body
length the researchers proposed that Ptychodus
mortoni was over 11
meters long. This is in the range of modern basking sharks
(Cetorhinus
maximus) and whale
sharks, and a few isolated teeth hint that there may have been
individuals (or even a different species) even larger in size.
Along with the shell-crunching mosasaur Globidens
and the even more ancient placodonts,
Ptychodus mortoni
was one of the largest shellfish-eating animals ever.
[This post was inspired by
Carl
Zimmer's post on the enormous filter-feeding fish Bonnerichthys
published last week.]
Shimada, K., Everhart, M.,
Decker, R., & Decker, P. (2010). A new skeletal remain of the
durophagous shark, Ptychodus mortoni, from the Upper Cretaceous of
North America: an indication of gigantic body size Cretaceous
Research, 31 (2), 249-254
DOI: 10.1016/j.cretres.2009.11.005
Great
white shark is more endangered than tiger, claims scientist
Recent
research suggests there are more tigers left in the wild than
there are great white sharks
Their poor public image may
mean
great white sharks go extinct before the tiger. Photograph:
Brandon Cole/Getty
Great white sharks may be
more
endangered than tigers, with only a few thousand left in the
world's oceans, according to a leading marine biologist.
The grim assessment suggests
that fishing
and collisions with shipping vessels have taken a devastating toll
on the ancient predators.
The World
Conservation Union, which operates the red
list of endangered species, lists great white sharks as
vulnerable but has no official estimate of their global
population. But a recent survey suggests that great whites have
fallen below 3,500 individuals, the number of tigers
conservationists believe are left in the wild.
A team led by Barbara Block, a
marine biologist at Stanford University, used radio transmitters
to track more than 150 great white sharks off the coast of
southern California.
"The estimated total
population of great white sharks in the world's oceans is actually
less than the number of tigers," said Ronald O'Dor, a senior
scientist at the Census of Marine
Life, an international collaboration that is cataloguing
marine
life.
"We hear an awful lot about
how endangered tigers are, but apparently great white sharks are
pretty close to the same level. Some people say 'I don't care,
they eat people,' but I think we have to give them a little space
to live in," O'Dor told the American
Association for the Advancement of Science meeting in San Diego
yesterday.
"The Australians have now
got a system where they put tags on great white sharks and they
have receivers on the beaches so when a great white comes into the
bay the receiver automatically makes a cell phone call and tells
the guy in charge to close the beach. So we can co-exist with
marine life," he added.
In 2007, marine biologists at
Dalhousie University in Canada analysed records from fisheries and
research vessels dating from the 1970s to 2005 and found evidence
for a dramatic fall in shark populations. Tiger sharks and
scalloped hammerheads had declined more than 97% since the
mid-1980s, while numbers of smooth hammerheads and bull sharks
fell 99% off the east coast of the US.
SUV-Sized
Fish Were Earliest Filter-Feeders
By Jennifer
Viegas | Thu Feb 18, 2010 02:00 PM ET
Giant
whales are known for their open-mouthed filter feeding, but the
technique was likely devised by humongous fish that lived during the
Mesozoic.
Whales
include the world's largest animals, but newly identified fossils
reveal they were preceded by SUV-sized filter-feeding fishes that
emerged during the Jurassic Period, 170 million years ago, and
lived until the extinction event that wiped out dinosaurs and
numerous other species.
Although the now-extinct
fishes,
called pachycormiforms, were not closely related to whales, their
demise left an ecological niche void that whales, sharks and rays
filled starting around 56 million years ago, helping to explain the
top portion of today's marine food chain.
The fish fossils, described
in
the latest issue of Science,
also prove that filter
feeding emerged long before the first whales. For this method
of eating, the diner suspends itself in the water, mouth agape.
Water escapes through gill slits, leaving behind the filtered food.
It can help to have a big
mouth,
which many of these enormous fishes must have had.
Co-author Kenshu Shimada, a
research associate in paleontology at the Sternberg Museum of
Natural History, told Discovery News that one of the fish he and
his colleagues identified, Bonnerichthys,
grew to around 20 feet in length and swam through a seaway covering
what is today the state of Kansas.
"A previously described
species, Leedsichthys,
from the Jurassic of Europe that belongs to the same lineage that
includes Bonnerichthys
was even larger, likely reaching up to about 30 feet, which is the
most massive bony fish of all time," added Shimada, who is
also an associate professor in the Environmental Science Program
and Department of Biological Sciences at DePaul University.
For the study, led by
University
of Oxford scientist Matt Friedman, the researchers analyzed both
old and new fish fossils found in England, the U.S. and Japan. The
Kansas fish was previously thought to have been like a gigantic
swordfish, bearing fang-like teeth on its jawbones.
"However, our close
examination of the specimen showed that such a long snout and
fang-like teeth were not present in the fish," Shimada said.
"Rather, with a blunt massive head, the fish had long
toothless jawbones and long gill-supporting bones that are
characteristic of plankton-feeding fishes."
While this fish, and the
other
Dinosaur-Era
filter feeders, enjoyed a long existence on the planet, they were
no match for the K-T extinction event that killed off 70 percent of
all species then living on Earth.
"The filter-feeding
pachycormiforms, relying for food on small organisms low in the
trophic chain, had the perfect profile of a victim and became
extinct," wrote Lionel Cavin in a commentary that also appears
in Science.
Cavin is a curator in the Department of Geology and Paleontology at
the Natural History Museum in Geneva.
Cavin added, "The tropical
niche was later refilled, first with sharks and rays from around 56
million years ago and then with modern cetaceans (whales, dolphins
and porpoises) from 34 million years ago."
Yet another paper in the
latest
Science,
authored by the University of Otago's Felix Marx and George Mason
University's Mark Uhen, found that diatoms, a common type of
phytoplankton, along with climatic events, influenced the evolution
of cetaceans once they headed into the water.
Marx and Uhen believe that "a
great increase in diatom-based productivity, possibly by increasing
the bioavailability of silica and other nutrients in the Southern
Ocean and coastal upwelling zones around the world through
deep-mixing occurring around Antarctica" drove the evolution
of baleen whales, in particular.
The research sheds light on
why
marine mammals that can weigh over 190 short tons and grow to 108
feet in length may subsist on minuscule diatoms and other tiny, yet
prevalent, water dwellers, such as krill.
Shark
Alliance urges international trade restrictions for threatened sharks
Coalition
supporting proposals to add eight shark species to CITES Appendix II
10 March
20
Qatar:
Whether to protect eight shark species – spiny dogfish,
porbeagle, oceanic whitetip, scalloped hammerhead, great hammerhead,
smooth hammerhead, dusky and sandbar sharks – that are
vulnerable to international trade will be a question debated at the
15th Conference of the Parties to the Convention on International
Trade in Endangered Species (CITES).
The
Shark Alliance is calling on delegates from the 175 governments that
will attend the meeting to list these threatened shark species under
CITES Appendix II. Such action would require export permits for all
international trade and a determination that trade is legal and not
detrimental to the species’ survival.
Most
sharks are exceptionally susceptible to overfishing because they grow
slowly, mature late, and produce few young. For example, spiny
dogfish are pregnant for nearly two years, and porbeagles only give
birth to about four young per brood.
"Sharks
are exceptionally vulnerable animals and the species proposed for
CITES listing have been hit especially hard by international trade,"
said Heike Zidowitz, chair of Germany's shark science society, who
will head the Shark Alliance delegation to the CITES meeting. "It's
high time to view sharks not just as commodities, but as wildlife,
and to use this wildlife treaty to control the lucrative shark
trade.”
Spearheaded
by Germany, proposals to list porbeagle and spiny dogfish have been
formally introduced by Sweden, supported by the other Member States
of the European Community, and co-sponsored by the Pacific island
nation of Palau.
Porbeagle
and spiny dogfish, classified by the International Union for
Conservation of Nature (IUCN) as Endangered in the Northwest Atlantic
and globally as Vulnerable, are at risk primarily due to demand for
their meat, which drives international trade. In Europe, porbeagle
meat is among the most valuable shark meat, particularly in France;
spiny dogfish meat is more widely popular, found regularly in UK fish
and chip shops.
The
United States and Palau are proposing CITES listing for the oceanic
whitetip shark, categorized by IUCN as globally Vulnerable and the
scalloped hammerhead, listed as globally Endangered. The great
hammerhead, smooth hammerhead, sandbar and dusky shark have been
added to the latter proposal because the fins of these species
closely resemble those of scalloped hammerheads.
Hammerhead
shark fins are highly sought for use in the traditional, Asian
delicacy “shark fin soup.” Because their meat is
generally considered unpalatable, hammerhead sharks too often fall
victim to “finning” (slicing off a shark’s fins and
discarding the body at sea). Strong demand for fins is also a driving
force behind the depletion of oceanic whitetip sharks.
"We
congratulate Palau, the United States and Sweden for championing
strong proposals to list commercially valuable sharks under CITES
Appendix II," said Matt Rand, coordinator of the Shark Alliance
and director of Global Shark Conservation for the Pew Environment
Group, "We call on all other CITES parties to support the
proposed Appendix II listings for these 8 shark species before it's
too late."
For the
Shark Alliance position paper and more information on the sharks
proposals go to http://www.sharkalliance.org
For
further information or to arrange media interviews or B roll contact:
Sophie
Hulme, sophie@communicationsinc.co.uk, c: +44 7973 712 869
Dan
Klotz, Communications Officer, Pew Environment Group,
dklotz@pewtrusts.org,
c: +1 347-307-2866
