Scientists provide first large-scale estimate of reef shark losses in the Pacific Ocean

Posted By News On April 27, 2012 - 12:30pm
Scientists provide first large-scale estimate of reef shark losses in the Pacific Ocean

HONOLULU – April 25, 2012 -- Many shark populations have plummeted in the past three decades as a result of excessive harvesting – for their fins, as an incidental catch of fisheries targeting other species, and in recreational fisheries. This is particularly true for oceanic species. However, until now, a lack of data prevented scientists from properly quantifying the status of Pacific reef sharks at a large geographic scale.

In a study published online April 27 in the journal Conservation Biology, an international team of marine scientists provide the first estimates of reef shark losses in the Pacific Ocean. Using underwater surveys conducted over the past decade across 46 U.S. Pacific islands and atolls, as part of NOAA's extensive Pacific Reef Assessment and Monitoring Program (www.pifsc.noaa.gov/cred/) the team compared reef shark numbers at reefs spanning from heavily impacted ones to those among the world's most pristine.

The numbers are sobering.

"We estimate that reef shark numbers have dropped substantially around populated islands, generally by more than 90 percent compared to those at the most untouched reefs", said Marc Nadon, lead author of the study and a scientist at the Joint Institute for Marine and Atmospheric Research (JIMAR) located at the University of Hawaii, as well as a PhD candidate with Dr. Jerry Ault at the University of Miami's Rosenstiel School of Marine & Atmospheric Science. "In short, people and sharks don't mix."

To obtain these estimates, Nadon and his colleagues used an innovative survey method, called 'towed-diver surveys,' which were designed specifically for the census of large, highly mobile reef fishes like sharks. The surveys involve paired SCUBA divers recording shark sightings while towed behind a small boat.

"Towed-diver surveys are key to our effort to quantify reef shark abundance," said Ivor Williams, head of the team responsible for these surveys. "Unlike other underwater census methods, which are typically at an insufficient spatial scale to properly count large, mobile species, these surveys allowed our scientists to quickly record shark numbers over large areas of reef."

Curious gray reef sharks (Carcharhinus amlyrhynchos) at Kure Atoll in the Papahanaumokuakea Marine National Monument, Hawaii were studied as part of a study published April 25 in the journal Conservation Biology. An international team of marine scientists provide the first estimates of reef shark losses in the Pacific Ocean using underwater surveys conducted over the past decade across 46 US Pacific islands and atolls, as part of NOAA's extensive Pacific Reef Assessment and Monitoring Program. The team compared reef shark numbers at reefs spanning from heavily impacted ones to those among the world's most pristine. The results are sobering.

(Photo Credit: P. Ayotte)

The team crunched the numbers from over 1,600 towed-diver surveys, combining them with information on human population, habitat complexity, reef area, and satellite-derived data on sea surface temperature and oceanographic productivity.

The models showed the enormous detrimental effect that humans have on reef sharks.

"Around each of the heavily populated areas we surveyed – in the main Hawaiian Islands, the Mariana Archipelago, and American Samoa - reef shark numbers were greatly depressed compared to reefs in the same regions that were simply further away from humans." Nadon said. "We estimate that less than 10% of the baseline numbers remain in these areas."

Like all fishes, reef sharks are influenced by their environment. "They like it warm, and they like it productive," said Julia Baum, Assistant Professor at the University of Victoria, Canada, referring to the increase in reef sharks the team found in areas with higher water temperatures and productivity. "Yet our study clearly shows that human influences now greatly outweigh natural ones."

"The pattern – of very low reef shark numbers near inhabited islands – was remarkably consistent, irrespective of ocean conditions or region," added Williams.

"Our findings underscore the importance of long-term monitoring across gradients of human impacts, biogeographic, and oceanic conditions, for understanding how humans are altering our oceans," concluded Rusty Brainard, head of the Coral Reef Ecosystem Division at NOAA's Pacific Islands Fisheries Science Center, which conducted the surveys.

Using an innovative survey method, called "towed-diver surveys," involve paired SCUBA divers recording shark sightings while towed behind a small boat. This approach was designed specifically for the census of large, highly mobile reef fishes including sharks.

(Photo Credit: Marc Nadon)

In “Mass Extinctions: Nature’s Spectacular Staging of Natural Selection” Julian Lieb, M.D provides evidence that “die- offs” or mass deaths are episodes of natural selection, caused by activation of enzymes of the arachidonic acid cascade.

In prior publications, Dr Lieb showed that products of the arachidonic acid cascade are the agents of natural selection and evolution, differentiating between infertility and reproduction, and between health and longevity, illness and death. Mass deaths in nature have occurred chronically, but seem to have accelerated since December 2010, in among many others fish, birds, bats, honey bees, crabs, frogs, dolphins, whales, ducks, seals, forests, squid, grassland butterflies, chicks and countless other species. Invariably, a mass death has conjured up a wild guess as to its cause. Upon reading about the mass deaths of red -winged blackbirds, Lieb noted the presence in them of blood and blood clots. Drawing on his knowledge of the arachidonic acid cascade, he concluded that an environmental stimulus had activated thromboxane synthase, an enzyme in the cascade critical to regulation of clotting. Other mass deaths, he reasoned, might be caused by activation of enzymes involved in heart, respiraratory and brain function, including mood regulation, which would explain the synchrony in time and space. As for the excitant, movement of the magnetic north pole towards Siberia is the most likely, especially as electromagnetic fields paradoxically activate and inhibit enzymes directly and indirectly by acting on cell membranes.
Natural selection determines who becomes ill, the severity of the illness, and the outcome, the HIV pandemic an example of a chronic mass death. "It may metaphorically be said," Darwin wrote, "that natural selection is daily and hourly scrutinizing, throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers....
Prostaglandins and thus natural selection are paradoxical. In Western Vermont, 15 colonies of bats are surviving, and appear to be healthy. While baby right whales perished en masse, Pacific gray whales are flourishing. Bee colonies have collapsed in the countryside, but appear to be thriving in cities, snowy owls once rare are returning, and albatross’s are heavier, and flying longer distances. On the other side of the coin, dolphins are in the throes of the largest beaching on record. Prostaglandins function as signaling pheromones in the reproduction of fish, dysfunctional signaling possibly accounting for the dolphin beaching. The frog and white nosed bat fungi are dormant, and activated by depression of immune function by an environmental excitant.. In the aftermath of the Joplin tornado, 3 people were treated for an aggressive fungal skin disorder never seen before; the fungus must have been dormant, until activated by the force that instigated the tornado.
Lieb’s latest will alter the way we view natural selection and evolution, along with evolutionary medicine, the origins of life, and possibly seismic events and cosmic ancestry. He paints a picture of a fork in the road wrongly taken: with the biomedical communities’ premise that DNA and RNA in the nucleus, and enzymes and proteins in the cell, are of overwhelming importance in disease, rather than focusing on membrane lipids and the arachidonic acid cascade. Lieb has converted the concept of natural selection to accessible molecules, with unlimited practical applications.

“Mass Extinctions: Nature’s Spectacular Staging of Natural Selection” is available for sale online at Amazon.com, BookSurge.com, and through additional wholesale and retail channels worldwide.

Die-offs

Honey bees: Mites or pesticides du jour
Turtle doves: Overfeeding/indigestion
Blackbirds: Firecrackers
Sardines/anchovies: Icy water/lack of oxygen
Reef sharks: Saran wrap/hamburger pickles/human pheromones/tobacco/Pepsi/surf boarding/Reynolds Wrap/the Sunday Times Magazine section/speeding/umbrellas/sun glasses/souffles/Ben and Jerry's/ Pina Coladas/vinyl/selfishness/flatus.

Conclusion: Apparently, all must be exempt from natural selection

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