People, mostly divers, often ask me what can I do to help protect our marine environment..
I am but one person they say, I can’t make a difference
Recent research has shown precipitous declines in many coastal
and oceanic shark species in the Northwest Atlantic. It has been
estimated that, since 1986, hammerheads have declined by 89%,
thresher sharks by 80%, white sharks by 79% and tiger sharks by
65%. All recorded shark species, with the exception of makos,
have declined by more than 50% in the past 8 to 15 years.
http://www.sharkstewards.com/
WHAT CAN YOU DO TO PROTECT OUR OCEAN SHARKS?
PLEASE take a minute to sign a petition against shark finning that will be presented to the UN later this year.
http://www.sharkstew...take-action.htm
You can make a difference,
MORE?
WASHINGTON–A sharp decline in big sharks along the eastern seaboard has prompted a boom in other marine species that is devastating valuable commercial fisheries, researchers report today in the journal Science.
The study – by a team of Canadian and American scientists – found that intense fishing of sharks in the northwest Atlantic over the past 35 years has produced a cascade of unexpected effects. With fewer large predators, the number of rays, skates and small shark species has exploded and these species are decimating shellfish populations such as North Carolina bay scallops and Chesapeake Bay oysters.
As many as 73 million sharks are killed each year to supply fins for shark-fin soup, a Chinese delicacy.
Charles Peterson, a marine sciences biology and ecology professor at the University of North Carolina at Chapel Hill, who helped write the paper, said he and his colleagues calculated that, between 1970 and 2005, the number of scalloped hammerhead and tiger sharks declined more than 97 per cent along the East Coast, while bull, dusky and smooth hammerhead sharks dropped by more than 99 per cent. This group of coastal sharks have very important roles in organizing the ecosystem," Peterson said in a telephone interview, adding the team determined populations of 12 of the sharks' 14 prey species increased during the period.
The cownose ray, which summers in Chesapeake Bay and preys on local species, has benefited significantly from shark decline. The rays, with wingspan up to two metre, eat massive amounts of bay scallops, oysters, soft-shell and hard clams in Chesapeake Bay, Delaware Bay and other area estuaries.
Peterson, with University of South Alabama marine sciences professor Sean Powers, determined from ocean-bottom sampling that migrating rays are eating nearly all adult scallops in North Carolina's sounds. Their disappearance prompted the state to close its century-old bay scallop fishery in 2004.
With cownose rays now numbering 40 million, Peterson said scientists are worried the rays will target other species. "What are these rays going to be eating now to fuel their energy for migration, and just to stay alive? That's the fear.''
In another part of the study, three marine biologists at Halifax's Dalhousie University, Ransom Myers, Julia Baum and Travis Shepherd, used data from commercial fisheries and research surveys to document a sharp drop in 11 species of great sharks in the northwest Atlantic since the mid-1980s.
Myers, a renowned fisheries scientist, died Tuesday of a brain tumour in Halifax.
Overfishing also reduced the number of mature sharks along the eastern seaboard, according to a separate UNC survey. That study, undertaken every year since 1972, suggests average lengths of blacktip, bull, dusky, sandbar and tiger sharks have shrunk by between 17 and 47 per cent.
Baum noted the World Conservation Union's shark specialist group last month listed great hammerhead and scalloped hammerheads as in danger of extinction and dusky and sandbar sharks as vulnerable to extinction.
"Their populations are plummeting, and at the same time, the demand for shark fins in Asia is skyrocketing ... If the world doesn't get serious about shark conservation right now, we really risk losing a lot of these species.''
WASHINGTON POST
Mar 29, 2007 03:24 PM
Canadian Press
HALIFAX – The near extinction of several species of sharks is causing a dangerous ripple effect through the marine food chain, according to a new study that links their virtual disappearance to depletions of other sea life.
The report by a team of researchers at Dalhousie University in Halifax has found that species that were once the primary food source for certain types of large sharks are undergoing a population boom because there aren't as many sharks to prey on them.
The scientists contend that the explosive increase in about a dozen types of smaller sharks, rays and skates has caused a cascading effect throughout the ecosystem as they begin to deplete limited nutrient sources and alter nature's complex food web.
"It's incredibly serious," said Julia Baum, who co-wrote the report to be released Friday in the journal Science. "Everyone knows that the oceans are being overfished and it's the top predators that are being disproportionately hit by overfishing.
"Because they structure everything underneath them in the food web, we may be drastically changing and restructuring how the oceanic food web functions and operates."
The report states that shark populations off the eastern United States are in an even steeper decline that originally thought. Using data from fisheries logs and research surveys from 1970 to 2005, the team discovered that the abundance of several types of so-called great sharks has dropped by more than 99 per cent.
The bull and dusty sharks are verging on extinction, while hammerheads and great white sharks are in dangerously low numbers, Baum said, due largely to overfishing.
The controversial practice of finning – slicing the shark's fin off and then tossing the carcass overboard – has led to precipitous drops in most strains of the large predators globally, the report said.
"What we're seeing is a higher risk of extinction of these species in these areas, and the term we use as ecologists is functional elimination," Baum said, adding that finning kills as many as 73 million sharks a year worldwide for an industry that supplies fins for soups and other uses.
"It means that these great predators can no longer play their roles in the ecosystem as top predators. So they're no longer controlling the species in the food web below them."
The researchers, including the late Ransom Myers who passed away Tuesday, cited a specific example of how the removal of sharks is affecting other species.
Baum, a marine biologist, said they have for the first time linked the decimation of bay scallops in waters off North Carolina to an increase in cownose rays, which eat the delicacy. Sharks feed on the rays, but because there are now so few sharks, the ray population has been allowed to grow to more than 10 times what it was a decade ago.
Cownose rays have wiped out scallop beds to the point that the fishery has been closed every year off North Carolina since 2004.
"This ecological event is having a large impact on local communities that depend so much on healthy fisheries," said Charles Peterson, a professor of marine sciences and biology at the University of North Carolina and co-author of the report.
Baum said it's not clear what the increase in the other species will mean for the food chain and the wider ecosystem, but it's likely skates, rays and smaller sharks are disrupting the wider natural order in oceans around the world.
The loss of the bay scallop has already caused disruptions to seagrass, an important habitat for other marine life, because rays plow through the growth in search of scallops. Rays may also be inhibiting the recovery of oysters, hard clams and soft-shell clams.
Ken Frank, a fisheries scientist with the federal Fisheries Department, said the findings add to what he had discovered in an earlier research paper that looked at how the disappearance of cod affected the food chain.
Frank, whose study was published in Science in 2005, found that the collapse of cod and other large species led to a cascade effect. As the number of large predators declined dramatically, the fish they preyed on – herring, capelin, shrimp and snow crab – experienced a population explosion.
"There are interdependencies among the species, and when you cause these imbalances, you're going to get some effect elsewhere," he said from his office in Halifax.
"For many decades, it was thought this type of cascade effect was possible only in simplified systems like ponds, so seeing this occur in the marine system is alarming. It means we're modifying the way energy is flowing through these systems."
This latest scientific paper follows groundbreaking research Myers and Baum did in 2003 that found shark populations in the Atlantic had plunged dramatically since the mid-1980s.
"We know better now why sharks matter," Baum said. "Keeping top predators is critical for sustaining the health of the ocean."
Thanks,
Cornel
Edited by WreckWench, 03 April 2007 - 12:08 PM.
