Friday Fishy News - September 21

[Flattieman]

Hey Raiders,

The combination of my birthday last week and two weeks of exams has kept me busy! At last, I can get on the 'net! Enjoy the news:

Shark gives birth despite lack of mate

Betty Reid

The Arizona Republic

September 18

Students at Carl Hayden Community High School were stunned when a baby shark appeared in one of their fish tanks.

More amazing was that the mother shark had been in the tank alone for nearly four years.

Teacher Fredi Lajvardi and his Phoenix science students investigated and discovered that the birth is rare.

As far as we know, it is the third case worldwide.

This type of birth is known as parthenogenesis, in which an unfertilized egg develops into a new pup, said Lajvardi, program manager for the Carl Hayden Center for Marine Science.

"The mother's gene divides in half and recombines with its own collection of genes to create a new individual," Lajvardi said. "Normally, it would recombine with the father's half of the gene. But because there is no father, the mother provided the other half."

It was a learning moment for students who saw firsthand last week how through parthenogenesis a species can reproduce when a mate isn't present.

The week-old pup, whom students have named Dawn, was born to a white-spotted bamboo shark named Twilight, who has lived in one of the school's marine-science classrooms.

"When we found out it hatched, everyone rushed the tank," said Kristen Shriner, a 17-year-old senior who has overseen the care of the mother shark.

She and other students have been e-mailing scientists to find out how to properly care for Dawn.

For now, Dawn will remain at the school; outside scientists have been invited to visit.

GM glowing fish could be sold

The Sydney Morning Herald

September 12

Genetically-modified glowing fish are one step closer to being offered for sale in Australia to would-be pet owners looking for something a little different for their fish tank.

A United States-based biotechnology company applied earlier this year to the Gene Technology Regulator for permission to import and sell the so-called GloFish.

The zebra fish have been modified to include a fluorescent protein gene that comes from reef coral.

The gene makes the fish absorb light and then release it, so they appear to glow either red, green or yellow.

According to the latest report from the Gene Technology Regulator, consultation with experts and key stakeholders was held between April and June to identify any risks to human health and safety and the environment.

The regulator said its technical advisory committee found the fluorescent proteins were not likely to be toxic to humans or other organisms, or cause an allergic reaction.

The regulator noted the fish were already being sold in the US and Singapore.

On its website, Yorktown Technologies said the fish were originally bred to help detect environmental pollutants.

Scientists hope to modify the fish further so they only glow when they are in contaminated waterways.

The company's website cautions against releasing the fish into the wild, saying the tropical fish would not survive in non-tropical environments.

But some environmental activist groups including Greenpeace oppose the sale of the fish.

"We have no way of predicting what havoc they will cause when they are released into the wild," Greenpeace says on its website.

"Aquarium fish get introduced into native ecosystems all the time, and can survive in the warmer waters of some springs and around industrial wastewater pipes, so this really is no laughing matter. Any escape would be irreversible."

The company also warns pet owners should not eat the glowing fish.

"GloFish fluorescent zebra fish, like all ornamental fish, are not intended for human consumption; they should never be eaten," it says.

Fish in space help studies of balance disorders

Scientists seek answers to how the inner ears develop in microgravity.

By Ned Stafford

News @ Nature.com

Twenty-six baby fish are now orbiting Earth aboard an unmanned Russian spacecraft, in a long-delayed experiment that researchers hope will lead to a better understanding of inner-ear balance mechanisms in humans.

The cichlid fish (Oreochromis mossambicus) blasted off Friday morning (11:00 GMT) from Baikonur Cosmodrome in Kazakhstan, in a Foton-M3 craft atop a Soyuz-U rocket, as part of a package of life and physical science experiments organized by the European Space Agency.

Reinhard Hilbig and Ralf Anken, neuro- and developmental biologists at the University of Hohenheim in Germany, will monitor the larval fish to watch the growth of their otoliths — sensory organs that have a role in hearing and balance — in microgravity conditions during the 12-day mission.

Otoliths, also found in the inner ear of humans, are sensitive to gravity and linear acceleration and are essential for maintaining proper balance. They are composed of a mix of gelatinous material and calcium carbonate, which shift around in a viscous fluid when the head moves, stimulating hair cells and conveying information about movement to the brain.

Scientists think a misfunctioning otolith is the culprit for conditions such as Ménière's disease, which causes vertigo and 'ringing in the ears' in sufferers. But they do not yet understand exactly how this organ works. The otoliths of fish provide a good candidate for study, says Hilbig, because they function in exactly the same way as human ones but are considerably larger. This is because fish must orient themselves underwater, where other motion clues are suppressed.

Gravity groove

Previous tests have shown that larval fish exposed to 'hypergravity' conditions in a centrifuge grow smaller-than-normal otoliths than controls. This implies that otolith development is, at least in part, under neural control, says Anken. Somehow the fish brain signals the otolith to grow smaller, as it does not need to be as big or as sensitive in hypergravity as it would in normal conditions.

The next step to confirm neural control is to test whether microgravity makes developing otoliths grow to be larger (and so more sensitive) than normal. Anken says they are expecting the otoliths to "grow uncontrollably and asymmetrically" in low gravity if under neural control.

This would make the otolith an unusual bit of anatomy. "I am convinced that the mineralization of otoliths is the only known natural process of biomineralization that requires neuronal input," says Anken.

It could also point the way to treatments: controlling the neuronal process that determines otolith size in humans could be used to help those with balance disorders. Such treatments are a long way off, says Anken. "We are still doing the basic research. We first have to know how the otolith works, then we may eventually develop a treatment."

Frogs in space

Scientific curiosity about the effect of gravity on the otolith is not new. In 1970, NASA sent two bullfrogs into space to look at the effect of weightlessness on their otoliths, specifically to study motion sickness. The new experiment differs in that it looks at the brain's involvement in otolith development.

It is a course that Anken has been pursuing for years. "In 1998, NASA released an announcement for a space shuttle mission and we jumped on this train," he says. It turned out to be a slow ride. Their microgravity fish experiment was launched in early 2003 aboard the Columbia space shuttle, a mission that ended in tragedy on 1 February that year when the shuttle disintegrated on re-entry over Texas. The fish experiment was lost along with the seven crew members.

They now have a second chance. Their fish are housed in a special tank, holding 3 litres of water and tipping the scales at only 18 kilograms. Scientists can observe fish behaviour through a camera system that sends video streaming back to Earth. When the experiment crash-lands back on Earth, the fish will be retrieved for more detailed study.

Fish and plant losses forecast as Murray level falls

ABC News Online

September 20

The latest report on the health of the Murray-Darling Basin says water levels in lower parts of the Murray could fall dramatically in the next year.

The Murray-Darling Basin Contingency Planning Report says water levels below Blanchetown in South Australia are set to fall by almost one metre by next April and, in a worst case scenario, could drop by almost two metres by late next year.

It says many fish could die in the lower lakes and salinity in Lake Alexandrina is set to reach a measure of 2500 EC early next year.

The outlook for farmers is also grim.

SA Water Security Minister Karlene Maywald says it is likely to become harder for people to obtain water.

"People at Langhorne Creek, Currency Creek and the dairy industry and the vegetable industry around the lower lakes are going to have a very, very difficult year," she warned.

The report says it is likely there will be widespread permanent plant losses across the Murray system because of insufficient water allocations.

It says there could be even more pressure placed on irrigators with a recommendation that an emergency water reserve be established.

The SA Government supports that recommendation, while the Victorian Government is opposed because of the expected effect on irrigators.

But Mrs Maywald says critical human needs are the priority.

Environment experts say low water levels are already having a devastating impact on native fish in the lower lakes of the Murray system.

Sperm Transplant Between Fish May Preserve Endangered Species

By Simeon Bennett

Bloomberg.com

September 14

Transplanting reproductive cells between fish may help preserve endangered species or resurrect extinct ones, scientists in Japan say.

Researchers at Tokyo University of Marine Science and Technology injected immature sperm-creating cells from rainbow trout into salmon embryos with abnormal chromosomes to produce normal trout with healthy offspring. They also froze and thawed reproductive cells, known as spermatogonia, as a way to store genetic material of endangered fish.

One objective is building ``a kind of spermatogonia bank of various fish species,'' said Goro Yoshizaki, who participated in the research, in a telephone interview yesterday. Transplanting the stored cells may enable scientists to revive species that become extinct, he said.

Habitat destruction, over-fishing and the introduction of farmed fish to wild populations have caused some species in the U.S. and Japan to dwindle, including bull trout, golden trout and gila trout, Yoshizaki said. The Tokyo researchers are collaborating with the U.S. National Oceanic and Atmospheric Administration to freeze sperm from a population of endangered sockeye salmon from Idaho, he said.

The transplant technique, reported in the journal Science today, is being use to produce bluefin tuna, prized in Japan for sushi and sashimi dishes.

Rather than farming the tuna, which weigh as much as 600 kilograms (1,320 pounds), Yoshizaki is implanting their reproductive cells in mackerel, which are about 1,000 times smaller and can be farmed in smaller facilities, he said.

``If I take spermatogonia from tuna and transplant it into mackerel, that surrogated mackerel can produce tuna egg and sperm,'' Yoshizaki said. ``Then we could save a lot of cost and space and labor for tuna seed production.''

Three-quarters of world's fish stocks depleted: report

ABC News Online

September 19

An environmental report has found three-quarters of the world's fish stocks have been over-exploited, mainly by commercial fishing.

The WorldWatch Institute study says declaring marine parks may be the only way to reverse a big decline in fish stocks across the world.

It says there needs to be a radical change to fisheries management and has recommended that exclusion zones be introduced in the high seas.

Greenpeace Oceans campaigner Jason Collins says that means more of the world's oceans need to be declared no fishing areas.

"At the moment around the world, there's less than 1 per cent of the oceans that are in marine parks," he said.

"Less than 0.1 per cent of the world's oceans are fully protected in that there can be no fishing.

"That's a long way from the recommendations that are coming from reports like this, which are starting to point to much bigger figures such as protecting 40 per cent of the world's oceans from fishing."

Flattieman.