Shark deaths endanger scallop population By RANDOLPH E. SCHMID, AP Science Writer
44 minutes ago
WASHINGTON - Overfishing of powerful sharks — a top predator in the ocean — may endanger bay scallops, a gourmet delicacy
With fewer sharks to devour them, skates and rays have increased sharply along the East Coast and they are gobbling up shellfish, particularly bay
scallops, researchers report in Friday's issue of the journal Science.
Ecologists have known that reducing key species on land can affect an entire ecosystem, but this study provides hard data for the same thing in the
ocean, said lead author Charles H. Peterson of the Institute of Marine Sciences at the University of North Carolina.
Co-author Ransom A. Myers of Dalhousie University in Halifax, Nova Scotia, and Peterson were studying different ends of the food chain, Peterson said
in a telephone interview.
"Myers was working on great sharks and I was working on cownose rays and their impact on bay scallops and other shellfish. We realized that separately
we had interesting science, but together we had an absolute revelation," he said.
"We were able to show why these top predators matter," Peterson said. "We knew the answer right there, that there was a consequence."
Peterson, who works at the university center in Morehead City, N.C., said scallops used to be so abundant there that people were allowed to collect a
bushel a day. "The kids were able to see that food doesn't just come from a market," he said.
Now, scallops are very reduced, he said. "The rays, as they come through, eat all that are in any dense patch and have eaten so many there does not
appear to be enough to create spawning stock."
Scallops are an easy target because they do not burrow into the sand, Peterson said. Millions of rays from Chesapeake Bay migrate through the area, he
said. "What are they going to feed on to fuel their migration?"
In some areas they enter seagrass beds and dig up clams, but that is an important nursery habitat for shrimp, blue crabs and fish, Peterson said, "so
there is a high concern that we may now be cascading to habitat destruction."
Not so sure was Steve Murawski, director of scientific programs at the National Marine Fisheries Service. He said the links between the large sharks,
medium size rays and bay scallops were "tenuous."
There is very little food and feeding data on the rays, he said, and in terms of the decline of bay scallops, habitat degradation and environmental
issues could be factors, too. As for the increase in rays, he said, they used to be widely caught and discarded and fishing has declined in their
prime habitat.
Murawski, who was not part of the research team, said he is not saying there is no relationship among the sharks, rays and scallops, only that other
factors also need to be considered.
Robert E. Hueter, director of shark research at Mote Marine Laboratory in Sarasota, Fla., said scientists have warned about the effects of shark
depletion for years but there have been few studies to back them up.
This report, he said, "demonstrates plausible links between the decline of sharks, the subsequent rise of their prey, and the resulting decline of
those prey species' prey. You don't have to be a marine biologist to grasp this connection."
"Scientists will now debate the specific numbers and correlations in this paper, and sadly, Dr. Myers will not be around for that debate," he said.
Myers, 54, died Tuesday in Halifax.
Hueter, who was not part of the research team, said the "overall message is important and true: If we take out whole segments of ecosystems,
especially top predators like sharks, the balance among species is toppled, and the effects cascade throughout the system. And some of those effects —
such as a negative impact on other important fisheries, as in the Myers study — can be long-term and deleterious to human society."
Ellen Pikitch, executive director of the Pew Institute for Ocean Science, said scientists have known that the loss of the great sharks would ripple
through the ecosystem in some way, but this is "the first study to show consequences with hard data."Ken Bondy - 3-29-2007 at 12:40 PM
Extremely interesting OLDFEZZYWIG. Rays are primary prey for large sharks. I have noticed an increase in the numbers of rays in several places in
the Sea of Cortez over the past three or four decades. That is likely a result of the heavy killing of sharks. Makes a lot of sense. ++Ken++Iflyfish - 3-29-2007 at 04:55 PM
Only hard data counts........hmmmm? There are many ways of knowing. Lets see, if I take this cornerstone out, I wonder what will happen to the
building? ........hmmmmm? I guess we humans need a crisis to take positive action. This story makes me sad. Those east coast sharks have been hunted
in a big way. Are human beings genocidal? I think so. Crap in our own beds and then wonder why it stinks. Need a scientific study to gather hard data
that it is the crap that causes the stink. In the meantime it becomes normal for people to have stinky beds.
I am ranting aren't I. I will stop.
Ellen Pikitch, executive director of the Pew Institute for Ocean Science, said scientists have known that the loss of the great sharks would ripple
through the ecosystem in some way, but this is "the first study to show consequences with hard data."
Last week I saw an Arkansas Senator arguing with Gore over global warming. How much science does it take? Many still believe that humans were made in
seven days and that evolution is a myth. Sometimes I just want to rant. There, I am done.
Iflyfishwhennotrantingbajamigo - 3-29-2007 at 05:21 PM
I can't get an image out of my head from chapter 3 of Ken's book---the picture of numerous sharks killed for their fins. I wonder how images like that
might focus some intense light on a problem that not many people seem to know or even care about.woody with a view - 3-29-2007 at 07:32 PM
Quote:
Many still believe that humans were made in seven days and that evolution is a myth.
i heard that one 'round a campfire in BCS once!Skipjack Joe - 3-30-2007 at 09:36 AM
Quote:
Originally posted by Iflyfish
Lets see, if I take this cornerstone out, I wonder what will happen to the building? ........hmmmmm?
Robert Paine from your University of Washington (I believe you're from Washington) showed just that with his study of starfish in the mid-60's.FARASHA - 3-30-2007 at 11:30 AM
Quote:
Originally posted by bajamigo
I can't get an image out of my head from chapter 3 of Ken's book---the picture of numerous sharks killed for their fins. I wonder how images like that
might focus some intense light on a problem that not many people seem to know or even care about.
GREAT THREAD :
2006 WAS THE YEAR OF THE SHARKS - and couple of Organisations tried to put some Shark species on the LIST of ENDANGERED SPECIES. With quite good
results.
With the effort of those Organisations the finning is banned on many places now. And the fisherman have been provided with alternatives for a
living, beside education.
Still - there is more to be done.
This YEAR is the YEAR of the DOLPHIN - don't miss the chance to sign up and be part of the support.
To prevent the next cornerstone to be taken away.
Have a look for some info -http://www.yod2007.org/en/Start_page/index.htmlOLDFEZZYWIG - 3-30-2007 at 12:23 PM
Yep ,
They also fished out all the big Sea Bass who used to eat all
the trigger fish . Now the trigger fish seem like the only thing I
catch when I am in close fishing . Though they do may a decent ceviche .Cypress - 3-30-2007 at 12:37 PM
Sorta spooky!