Female Shark Reproduced Without Male DNA, Scientists Say

By HENRY FOUNTAIN

Published: May 23, 2007

A hammerhead shark that gave birth in a Nebraska aquarium reproduced without mating, a genetic analysis shows.

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Henry Doorly Zoo

This shark’s mother is said to have had no contact with male sharks.

This form of asexual reproduction, called parthenogenesis, has been found in other vertebrate species, including some snakes and lizards. But this is the first time it has been documented in a shark.

Researchers from the Guy Harvey Research Institute at Nova Southeastern University in Florida and Queen’s University Belfast in Northern Ireland found no male DNA in the female baby shark, which was born in December 2001 and died shortly after birth, apparently killed by another fish. The mother was one of three female bonnetheads, a small hammerhead species, that had been captured in Florida and kept without male sharks for three years in the Henry Doorly Zoo in Omaha.

At the time of the birth, many scientists thought that the female had mated with another species, or that it had used sperm obtained years before. Female sharks are capable of storing sperm, although none have been known to store it as long as these sharks had been isolated.

But through the analysis “it was pretty clear that there was no male contribution,” said Mahmood S. Shivji, director of the Guy Harvey Research Institute and author of a paper on the finding being published online today by the journal Biology Letters.

Instead, the female shark’s own genetic material combined during the process of cell division that produces an egg. A cell called the secondary oocyte, which contains half the female chromosomes and normally becomes the egg, fused with another cell called the secondary polar body, which contains the identical genetic material.

Robert E. Hueter, director of the Center for Shark Research at the Mote Marine Laboratory in Sarasota, Fla., said the finding helped fill a gap in understanding of parthenogenesis, which has been found to occur in most vertebrate lines except mammals and, until now, cartilaginous fishes like sharks.

“These guys have proven their case,” Dr. Hueter said of the researchers.

Dr. Shivji said that after the bonnethead birth was reported, keepers at the Belle Isle Aquarium in Detroit reported similar virgin births by white spotted bamboo sharks. While those births have not been proved to result from parthenogenesis, Dr. Shivji said, it is reasonable to assume they did. And if it is found in these two species, “it seems not unreasonable to think this is probably more widespread in different shark lineages,” he said.

Gordon W. Schuett, an adjunct professor at Georgia State University who discovered parthenogenesis in a snake in 1997, said it would probably be discovered in more species “because we know to look for it.”

Previously, Dr. Schuett said, zookeepers and others tended to discount evidence of virgin births precisely because they were so out of the ordinary. But in recent years it has been found in Komodo dragons, other lizards and snake species.

“It’s all over the place,” Dr. Schuett said.

Still, parthenogenesis among vertebrates tends to be rare, and, while it may occur in the wild, has been documented only in captivity.

“It’s a last-resort tactic that animals use when they absolutely can’t find another mate,” Dr. Hueter said.

While it has the advantage of ensuring the survival of a species in the absence of males, it also comes at a cost: a loss of genetic diversity. And that, Dr. Shivji said, may spell conservation problems for some shark species whose populations are declining. If it becomes more difficult for female sharks in the wild to find a mate and instead they reproduce through parthenogenesis, then the offspring will be less genetically diverse, making the species more susceptible to diseases and other problems.

But Dr. Hueter said he thought it unlikely that most sharks, which are highly mobile, would end up so isolated that parthenogenesis would be much of a factor. Sharks have plenty of other problems that are of potentially greater impact.

“I would be concerned about a lot of other things than whether or not a female shark can get a date for an evening,” he said.

Article at: http://www.nytimes.com/2007/05/23/science/23shark.html?scp=1&sq=virgin%20shark&st=cse

Japan's Famous Tsukiji Fish Market Braces for Tuna Trade Ban

By Shingo Ito, AFP
Photo By: Issei Kato , Reuters

TOKYO - As bartenders close the shutters in Tokyo’s glitzy nightlife district, just a short walk away handbells ring in the pre-dawn tuna auctions in an old warehouse in Tsukiji.

Veteran auctioneers call for bids for hundreds of snap-frozen tuna laid in neat rows in the world’s largest fish market, the size of more than 40 football pitches.

The ocean predators, laid out on steaming dry ice, have their tails cut to reveal oval windows of the burgundy flesh that has fetched as much as 175,000 dollars for a 232 kilogram (511 pound) fish here.

In the chilly halls, fishmongers with headbands and aprons slice the red flesh with large knives, while three-wheel trolleys are pushed through the narrow aisles.

The famous market on Tokyo Bay, long a must-see tourist spot, is facing a disputed relocation plan in coming years — but another threat is looming large, a possible cross-border trade ban on Atlantic bluefin tuna.

At a meeting in Doha, Qatar that runs until March 25, countries will vote on whether to declare bluefin a highly endangered species, alongside tigers, great apes and the panda, and ban its international trade.

A ban became more likely after the United States and the European Union last week backed the move ahead of the meeting of the Convention on International Trade in Endangered Species (CITES).

Decades of overfishing have seen stocks crash by more than two-thirds in the Mediterranean, from where giant freezer ships have long headed for Japan, which consumes three-quarters of the global bluefin catch.

But the move has sounded alarm bells in Japan.

“I can’t imagine sushi without tuna,” said Ayaka Mimura, a 21-year-old Tokyo university student, as she was buying seafood in Tsukiji.

“Of course, I oppose overfishing. But a sudden, total ban sounds unfavourable to me. We just eat fish the way others eat beef.”

It is a view shared by Japan’s government and fishing industry, who oppose and have threatened to ignore a trade ban, pushing instead for industry-based ways to make the catch more sustainable.

Japan last year pledged to help meet an accord to slash the total catch in the eastern Atlantic and Mediterranean by 40 percent, although environmental groups charge that such quotas are routinely exceeded.

“Overfishing has never ended under the current quotas,” said Wakao Hanaoka, a Greenpeace researcher. “It is necessary to protect the fish under the convention. I hope Japan will take responsible action.”

Hisashi Endo, a fishery agency official, said: “We are not optimistic about the meeting. We are concerned the result could set a new global trend and spread to the Pacific and other oceans.”

Japan sources 25,000 tonnes of bluefin tuna a year from the Pacific and 19,000 tonnes from the Atlantic. The country also has about 20,000 tonnes of deep-frozen bluefin tuna in domestic stock.

Yuichiro Harada, who works with a Tokyo-based lobbying group that says it supports “responsible” bluefin tuna fishing, said: “It’s quite unfair to treat tuna the same way as lions and tigers and elephants.

“Unlike those animals, tuna can bear hundreds of millions of eggs and is internationally recognised as a commercial food.”

Tsukiji fishmongers staged a small protest last week, yelling out “Protect tuna in the markets!” and “We oppose a decision at the Washington Convention” as the CITES treaty is also known.

Traders fear a steep price hike for the bluefin, known as “kuro maguro” or black tuna in Japan. A piece of “otoro” or fatty underbelly, now costs 2,000 yen (22 dollars) at high-end Tokyo restaurants.

“I bet prices will jump on the same day if the ban is adopted,” said Mitsunobu Iida, a tuna wholesaler and sushi restaurant owner.

“That’s what market sentiment is always like. We can’t ask our customers to accept a price hike easily.... If we raised the price, people would stop buying it. I’m afraid we are going to have a hard time.”
© Copyright (c) The Calgary Herald

Read more: http://www.calgaryherald.com/business/Japan+famous+Tsukiji+fish+market+braces+tuna+trade/2682850/story.html#ixzz0iJEu27Pv

Fish Developed With 'Six-Pack Abs'

Development of More Muscular Trout Could Boost Commercial Aquaculture
ScienceDaily (Mar. 11, 2010) — A 10-year effort by a University of Rhode Island scientist to develop transgenic rainbow trout with enhanced muscle growth has yielded fish with what have been described as six-pack abs and muscular shoulders that could provide a boost to the commercial aquaculture industry.

Terry Bradley, a URI professor of fisheries and aquaculture, said his research into the inhibition of myostatin, a protein that slows muscle growth, has obtained "stunning results" in the last two years, with trout growing 15 to 20 percent more muscle mass than standard fish.

"Belgian blue cattle have a natural mutation in myostatin causing a 20 to 25 percent increase in muscle mass, and mice overexpressing myostatin exhibit a two-fold increase in skeletal muscle mass. But fish have a very different mechanism of muscle growth than mammals, so we weren't certain it was going to work," Bradley said.
According to Bradley, the number of muscle fibers in mammals is limited after birth, but in fish, muscle fiber numbers increase throughout their lifespan. Since inhibition of myostatin increases the numbers of muscle fibers, it had been a mystery as to whether inhibiting myostatin would cause an increase in muscle growth in fish.
Bradley and a team of graduate students spent 500 hours injecting 20,000 rainbow trout eggs with various DNA types designed to inhibit myostatin. Of the eggs that hatched, 300 carried the gene that led to increased muscle growth. After two years, most exhibited a "six-pack ab" effect, even though fish lack standard abdominal muscles. They also have increased musculature throughout, including a prominent dorsal hump that made them look like they had muscular shoulders.
The first generation of transgenic trout were subsequently spawned, and offspring carrying the gene in all of their muscle cells have been produced. Studies are under way to determine if the fish grow at a faster rate as well.
"Our findings are quite stunning," said Bradley, who also studies salmon, flounder and tuna. "The results have significant implications for commercial aquaculture and provide completely novel information on the mechanisms of fish growth. The results also allow for comparisons between the mechanisms of growth of muscle in mammals versus fish, and it could shed light on muscle wasting diseases in humans."
About 500,000 metric tons of rainbow trout are raised each year in aquaculture facilities in the United States and Europe. In the U.S., some 1,000 trout farms produce approximately $80 million of trout annually, mostly in Idaho, New York, Pennsylvania and California. Assuming Bradley's transgenic fish meet with regulatory approval, it could provide a boost to the industry by enabling aquaculturists to grow larger fish without increasing the amount of food the fish are fed.
"One of the advantages of this approach is that the modified genes introduced into the fish use the same mechanism and cause the same type of effect that occurs naturally in Belgian blue cattle and other 'double muscled' animals," said Bradley.
While the transgenic trout may look like bodybuilders, Bradley said they exhibit normal behaviors. He will continue to study the fish to learn if the new gene affects any other genes, and to determine if new husbandry practices will aid in the raising of the trout.

Quake Threatens Important Chile Fish, Wine Sectors

Ravages infrastructure lifeline for Chile's important fish and wine sectors

By VIVIAN SEQUERA and ALAN CLENDENNING Associated Press Writers
TALCAHUANO, Chile March 3, 2010 (AP)

The tsunami that hit this coastal city sent 50-ton fishing boats crashing onto land and demolished its port — wiping out the $40 million in business that courses through the local economy from the annual anchovy and sardine catch.

Less than 100 miles (160 kilometers) away, Chile's economy took another beating as the mammoth quake downed bridges and opened up vast crevices on the nation's only north-south highway, paralyzing the export lifeline for the nation's renowned farm-raised salmon industry.

And Chile's telecommunications system was still so badly out of whack Wednesday — four days after the quake — that local and foreign investors who own vineyards that carpet the hardest-hit areas couldn't reach winery employees by phone or Internet to discuss the upcoming harvest.

"You have to get grapes from the vineyards to the winery, and I don't know the condition of the roads around the winery," said Mark Osmun, spokesman for California's Jackson Family Wines, owner of the Vina Calina winery in the devastated Talca region about 65 miles (105 kilometers) from the quake's epicenter.

Chile's horrendously destructive 8.8-magnitude quake doesn't have a price tag on it yet, though President Michelle Bachelet mentioned a $30 billion estimate when she met Tuesday with U.S. Secretary of State Hillary Clinton, who delivered 25 satellite phones as a down payment on disaster assistance.

But the quake has already forced tens of thousands into unemployment with no end in sight in the nation's south-southwest area and will almost certainly mean higher salmon prices at U.S. supermarkets. It also translates into higher wine production costs for an industry already hurt by the declining value of the U.S. dollar.

Chile's copper industry, which supplies a third of the world's copper, wasn't badly affected because most operations lie north of Santiago. Mining company Anglo American PLC said Wednesday that one of its plants near the epicenter had considerable damage, "preventing the resumption of operations until further notice."

The large ships that fish Chile's rich waters far out to sea rode out the tsunami and can deliver their catches to ports unaffected by the earthquake.

But an estimated 1,000 boats that stick closer to shore were destroyed, said Gonzalo Olea, a spokesman for Chile's National Confederation of Small Fishermen. Some boats ended up kilometers (miles) inland.

The quake hit just as the three- to four-month fishing season was starting for 760 small-scale fishermen in Talacahuano, said Nelson Estrada, president of their union representing fishermen who now wander around with nothing to do, their jeans stained by black mud that the tsunami left behind.

"The season has been killed," Estrada said from the wrecked port reeking of putrid fish.

The region where they ply the waters nets 4 percent of the world's annual catch of seafood, some 2 million metric tons, said Hector Bacigalupo, general manager of Chile's National Fishing Association. At least 90 percent — including hake, mackerel and shellfish — goes to the United States, Australia and Africa.

Many fishermen also lost their homes, an eerie replay of Louisiana's shrimpers who were devastated by Hurricane Katrina and haven't fully recovered five years later.

Even Chilean fishermen whose boats survived intact may find it hard to work because it will take months or more to repair unloading piers and replace equipment that looters stole from fish-processing plants.

"Now the boats are paralyzed because there's no way to unload," said Carlos Rivas, a boat captain in Hualpen.

Some went out to sea anyway in the quake's aftermath, buoying their boats in bays after returning and rowing to shore to give their catch free to hungry survivors in a zone that is home to a large proportion of the earthquake's death toll.

Chile's salmon industry that raises fish in pens and competes heavily with Norway and Canada was spared from major damage because it lies hundreds of kilometers (miles) south of Talcahuano. But the sector's transportation chain was thrown into crisis when the tremor hit before dawn Saturday.

On maps, Chile looks like a slender chili pepper with the north-south Pan American Highway sandwiched between the Pacific Ocean and the Andes Mountains. Fresh salmon must be driven in refrigerated trucks for 900 kilometers (560 miles) along the now damaged road to the airport in Santiago to be loaded onto cargo planes flying to the U.S. and elsewhere.

The airport, meanwhile, hasn't reopened to commercial flights.

Some Chilean salmon suppliers are trying to set up a trucking route to Buenos Aires, Argentina, said Kimberly Gorton, president of Boston-based seafood distributor Slade Gorton & Company Inc. But that route is twice as long, and trucks would have to navigate high mountain passes.

Still, no one knows how long it will take to repair all the damaged bridges and highway pavement on Chile's highway.

"Clearly what's going to happen is a reduction in supply is going to cause an increase in prices," Gorton said. "It's sad because Chile is so dependent on its fishing industry for exports."

Some of Chile's oldest and most famous wine-growing regions lie in the heart of area slammed by the earthquake.

More: http://abcnews.go.com/Business/wirestory?id=9998190&page=3

Observatory
Fish Use UV Patterns to Tell Species Apart


By HENRY FOUNTAIN
Published: February 26, 2010

If you’ve seen one damselfish, you’ve seen them all.

That may be true for people, who have a difficult time telling some damselfish species apart. But the fish themselves see it differently, according to a study in Current Biology. They can use ultraviolet facial patterns to tell one species from another.

Ulrike E. Siebeck of the University of Queensland in Australia and colleagues studied Pomacentrus amboinensis and P. moluccensis, two species of damselfish capable of seeing light at the ultraviolet end of the spectrum. They are also highly territorial: P. amboinensis males, for example, will chase off unfamiliar members of their species because they are seen as competitors, but go easier on P. moluccensis intruders.

To people, the two species of reef fish look practically identical. But under UV light they are revealed to have distinctly different patterns in the scales around the eyes. “These are really fine, intricate patterns that we can’t see at all,” Dr. Siebeck said.

The question for her and her colleagues was whether the patterns, and the ability to see them, had an effect on behavior. In a series of experiments in which, among other things, they placed fish inside a glass chamber equipped with UV filters, they showed that P. amboinensis used the patterns to discriminate between the two species.

The work provides support for the idea, suggested by others, that the ultraviolet part of the spectrum may be a way for some species to communicate secretly, in ways invisible to those that cannot see UV.

Researchers solve mystery of deep-sea fish with tubular eyes and transparent head

This article is about a year old but I thought it was worth sharing

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Researchers at the Monterey Bay Aquarium Research Institute recently solved the half-century-old mystery of a fish with tubular eyes and a transparent head. Ever since the "barreleye" fish Macropinna microstomawas first described in 1939, marine biologists have known that its tubular eyes are very good at collecting light. However, the eyes were believed to be fixed in place and seemed to provide only a "tunnel-vision" view of whatever was directly above the fish's head. A new paper by Bruce Robison and Kim Reisenbichler shows that these unusual eyes can rotate within a transparent shield that covers the fish's head. This allows the barreleye to peer up at potential prey or focus forward to see what it is eating.

Deep-sea fish have adapted to their pitch-black environment in a variety of amazing ways. Several species of deep-water fishes in the family Opisthoproctidae are called "barreleyes" because their eyes are tubular in shape. Barreleyes typically live near the depth where sunlight from the surface fades to complete blackness. They use their ultra-sensitive tubular eyes to search for the faint silhouettes of prey overhead. Although such tubular eyes are very good at collecting light, they have a very narrow field of view. Furthermore, until now, most marine biologists believed that barreleye's eyes were fixed in their heads, which would allow them to only look upward. This would make it impossible for the fishes to see what was directly in front of them, and very difficult for them to capture prey with their small, pointed mouths...

(Rest of the article here: http://www.mbari.org/news/news_releases/2009/barreleye/barreleye.html)

I will be in the Ichthyology lab this evening from 5-6pm to answer questions and help you prepare for the lab practical (tomorrow!!!). This is a valuable opportunity to test your ability to recognize anatomy and key fish! You can practice/study in the lab at other times as well; but this is the best time to come in if you feel like you need clarification in certain areas.

*****I will be most able to help you if you email me questions prior to 4:00pm today!

-Em :)