Tag Archives: Fish


Australia forms marine park to protect humpback calving zone

A marine park will be formed at Camden Sound, Australia, in an effort to protect the Humpback whale (Megaptera novaeangliae). Once hunted to the brink of extinction, the humpbacks have already bounced back considerably thanks to conservation efforts and they are now much sought after by whale-watchers, particularly off parts of Australia, Canada, and the United States.

Humpback whale

The Government recognises the Kimberley as one of Australia’s special places,” said Premier Colin Barnett as he unveiled the plans for the park. “That is why we are protecting Camden Sound, making it a marine park, and developing and implementing our Kimberley Science and Conservation Strategy. This strategy will balance the need to develop industry and create wealth with the expectation that the environment and special places will be protected. This remarkable area warrants protection as a first step in the broader conservation of the Kimberley.”

Environment Minister Donna Faragher added that Camden Sound is the largest calving area for humpbacks in the southern hemisphere.

More than 1000 humpback whales can be found in the Camden Sound ‘maternity ward’ during the calving season,” Faragher said. They are part of the biggest population of humpback whales in the world – numbering about 22,000 – that migrate from Antarctica every year to give birth in the waters off the north of our State.”

Faragher said the park will be created in consultation with the local indigenous community and all stakeholders with an interest in the area.

Allowing for consultation, including a public comment period of three months, a marine park could be established as early as mid-2010.

Camden Sound

Camden Sound is a bay in the Indian Ocean situated in the Kimberley region of Western Australia. The sound is a highly bio-diverse region; home to animals such as dugongs, crocodiles, sea-snakes, sharks, rays, and three species of sea turtle. Indo-Pacific humpbacked dolphins, Bottle-nosed dolphins, and the newly recognized Snub-fin dolphin can all be found within the borders of the proposed marine park. The sound is also visited by several species of whale, including False Killer whale, Bryde’s whale, Minke whale, and Dwarf Sperm whale. The corals reefs in the region are still fairly unharmed and varied the extensive mangrove forests found along the shores acts as nursery areas for fish and invertebrates.

Humpback whales born in Camden Sound stay there for several months after birth to grow big and strong enough to survive the long journey to the chilly Arctic waters where the humpbacks feed during the summer.

When opposites won’t attract; same-colour medakas preferentially selective for each other

An international team of researchers have shown how one single gene mutation is capable of making the medaka, a Japanese killifish, loose its attractive colours and display a drab grey colour which renders them significantly less attractive to medakas of the opposite sex – unless that potential mate is grey too.

In the wild, medakas come in a wide range of colours, including orange, brown and drab grey.

We observed that the grey medaka were often rejected in favor of their brown or orange rivals“, says lead author Shoji Fukamachi. “This is the first demonstration of a single gene that can change both secondary sexual characteristics and mating preferences“.

As mentioned above, you don’t have to fear ending up without a mate just because you happen to be a grey medaka – you just have to go out looking for another grey specimen since the study showed greys to be preferentially selective for each other. This preference for choosing a member of your own colour suggests that sympatric speciation could occur in medakas as the colour determining gene is mutated, i.e. new species may form as the medakas choose to mate with specimens of their own colour.

The research is a collaborative effort by researchers from the University of Konstanz, Germany and from the University of Tokyo, Japan. The study has been published in the open access journal BMC Biology.

How to tell if a salmon is wild or farmed?

Telling a wild salmon from a farmed one can be tricky, especially if you don’t want to kill or injure the fish in question. To solve this problem, Dr Elizabeth Adey of the Scottish Association for Marine Science (SAMS) have developed a way of using fish scale analysis to determine the origin of a salmon.

salmon

Fish scales grow like tree rings and preserves a chemical record of the water in which the fish lived as each new section of the scale was formed. The new method, which was developed in collaboration with the National Oceanography Centre in Southampton, checks the amount of manganese present in the fish scale. During her work, Dr Adey discovered that the scales of farmed salmon have a very high manganese content compared to the levels found in scales coming from their wild counterparts.

This is probably caused by manganese supplements in fish food, and also because conditions underneath the fish cages promote recycling of manganese in the water column,” Dr Adey explains. Using the new method, Dr Adey and her team was able to distinguish between farmed and wild salmon with 98% accuracy.”Because of its non-destructive nature, this technique could be used to assess the proportion of farmescape salmon present in any river, and therefore identify where additional conservation and wildlife protection measures are needed,” says Dr Trueman, a geochemist with the University of Southampton’s School of Ocean and Earth Science, based at that National Oceanography Centre. “Salmon farming is a big, intensive business. In 2006, around 130,000 tonnes of salmon were farmed in Scotland for the table. Wild populations of Atlantic salmon are in serious decline across their whole range and the total wild population returning to Scottish rivers in the same year is estimated at less than 5000 tonnes. Wild fish are rare and expensiveso there is a strong incentive for fraudulent labeling. Farmed fish also escape into rivers, harming the wild population. Unfortunately, it can be difficult to distinguish between farmed and wild fish.

In the future, the new technique may also be able to point out which individual fish farms that need to implement more efficient methods for keeping their salmons in. In some Norwegian rivers, more than 50 percent of the salmon are now escapees. Escaped fish can carry disease to wild populations, and there is also a risk of genetic pollution since farmed fish haven’t gone through the same natural selection process as wild fish.

Mexican researchers breed gar in captivity using new sexing technique

The gar family, famous for containing the largest fresh water fishes in Mexico, is currently at risk of becoming extinct – something which Mexican researchers are working hard to prevent.

This fish is native to our country and the United States”, Doctor Eduardo Mendoza Alfaro explains. “Currently, its populations are threatened due to excessive hunting, — for there are no rules that regulate its fishing — urban expansion, pollution, and particularly the dams´ construction, which caused the destruction of their breeding grounds. These factors led this species to reduce to only forty adult specimens in the country — in inventory and considered national patrimony.”

Doctor Eduardo Mendoza Alfaro*, a member of the ‘Eco-physiology Group,’ from the Universidad Autonoma de Nuevo Leon’s (UANL) School of Biological Sciences Ecological Department, is currently researching gar reproduction and diet in order to find ways of efficiently raising gars in captivity. The team also works with several other types of endangered fish, but the gar – which can reach a length of three meter and is highly esteemed by sport fishers – is arguably the most iconic.

 Lepisosteus platostomus - Shortnosed gar picture
Lepisosteus platostomus – Shortnosed gar, Copyright www.jjphoto.dk

One of the hurdles that must be overcome to ease gar raising in captivity is how to distinguish males from females. In a reproductive facility you want to keep an ideal sex ration – with gars this is four males for each female – but this is difficult to accomplish without reliable sexing methods.

We could not identify females and males, because, morphologically, they are

Identical”, says Dr Alfaro. “Even though most of the fish can be cannulated in order to know their gender and maturation status, for gar is not the same process, that is what represents

the first obstacle for scientifics when they were carrying out the reproduction

studies and establishing fish’s gender. Most of the fish can be cannulated by introducing them a catheter in the oviduct in order to take the oocytes (ovules). However, this process cannot

be carried out with the gar. They are so primitive fish, which date since 189 million years ago and their urinal tract which ends with the oviduct in a kind of sewer that cannot allow the

cannulation.”

To overcome the problem, Dr Alfaro and his team devised a new technique based on a molecule known as vitelogenine. Vitelogenine is present only in females from puberty and onwards, and can be used as a biochemical marker.

First, the team purified the molecule. Then, they created antibodies against the molecule for recognizing and quantifying it.

Currently, we got an extremely sensitive method which allows us to dose this molecule with only a small sample of fish’s skin mucus, says Dr Alfaro. “So, we not only identified if it is a female or a male, but we can follow up females’ sexual maturation.”

Gar facts

· The gar family evolved during the cretaceous.

· A gar can weigh up to 220 lbs.

· The gar is a predatory fish with an elongated jaw. It is sometimes referred to as alligator fish due to its resemblance to the predatory reptile. It has numerous sharp teeth and a body protected by hard scales.

· Gars spawn in swamps during the wet season and destruction of wetlands poses a problem for them.

· In the wild, several males follow the female wanting to fertilize her eggs as she deposits them.

· Mexico is the world’s leading gar specimen producer.

*Roberto Eduardo Mendoza Alfaro is a professor at the UANL´s School of Biological Sciences Ecology Department in Leon, Mexico.

Flatfish – how did its eyes get to the same side of the head?

If you’ve ever wondered how the eyes of flatfish like flounder and sole ended up on one side of the head, you should take a closer look at a newly published article by Dr Matt Friedman.

Dr Friedman, who recently took up a post at Oxford University, has been investigating this mysterious eye migration using 50-million-year-old fossilized Acanthomorph fishes from Italy and France, and has managed to show that the change was slow and gradual rather than abrupt. Over millions of years, the positions of the flatfish eyes have gradually changed, little by little.

Addressing the Society of Vertebrate Palaeontologists’ (SVP) annual meeting at the University of Bristol today, Dr Friedman said: ”Flatfishes and their profoundly asymmetrical skulls have been enlisted in many arguments against gradual evolutionary change, precisely because it is difficult to imagine how intermediate forms might have been adaptive. My work provides clear evidence of the kinds of intermediates deemed ‘impossible’ by earlier workers and answers this long-standing riddle in vertebrate evolution.”

The most ancient Acanthomorph fishes had asymmetrical skulls, but the eyes were still located on both sides of the head. From these foregoers, intermediate species evolved and one of the eyes gradually moved across the head until both eyes ended up on the same side – millions of years later.

The flatfish group puzzled 19th century scientists trying to grasp the new Darwinian ideas, because during that epoch, the group’s fossil record was incomplete and it was unclear how the gradual migration of one eye could have come about. Today, a much broader range of fossil fish is available to science and Dr Friedman’s study included over 1,200 fossil specimens belonging to over 600 different species.

New species of shark found in Californian waters; male has retractable sexual appendages on the forehead

black ghost sharkFor the first time since 1947, a new species of cartilaginous fish has been described from Californian waters. The new species – Hydrolagus melanophasma – belongs to a group of sharks known as Chimaeras or ghostsharks.

Chimaeras are fairly closely related to the true sharks, but their evolutionary lineage branched off from the true sharks nearly 400 million years ago. Just like sharks, ghostsharks have cartilage skeletons instead of bony skeletons and they carry out internal fertilization using claspers. Unlike the true sharks however, males of the Chimaera group are fitted with retractable sexual appendages on the forehead and in front of the pelvic fins. Most known species also have a venomous spine in front of the dorsal fin.

The new species, the Eastern Pacific black ghostshark, was caught and preserved as early as the 1960s but hasn’t been formally named and described until know since its taxonomic relationships with other Chimaeras remained unclear. It is now placed in the genus Hydrolagus – the water rabbits – a genus named after the grinding tooth plates used by its members; plates somewhat similar to the teeth of a rabbit.

You can find out more about Hydrolagus melanophasma in the September issue of the journal Zootaxa. The article in which the new species was described is the result of the combined efforts of a team of scientists, including Academy Research Associates David Ebert and Douglas J. Long, graduate student Kelsey James from the Moss Landing Marine Laboratories, and Dominique Didier from Millersville University in Pennsylvania.

Researchers improve zebra fish cloning – “We used the same entrance that sperm uses”

A team of scientists at the Michigan State University has found a new, more efficient method for cloning zebra fish.

After the mouse, it is the most commonly used vertebrate in genetic studies,” said Jose Cibelli, an MSU professor of animal science and one of the paper’s co-authors. “It is used in cancer research and cardiovascular research because they have many of the same genes we have.”

Zebra fish is also used by scientists researching normal development and birth defects, as well as various human diseases and the functions of cell populations within organs.

Up until now, zebra fish cloning has had a low success rate, but the new Michigan method has changed this. The new method uses ovarian fluid from a Chinook salmon to keep the unfertilized egg alive.

This worked well, because it kept the egg inactive for some time”, Cibelli explained. It gave us two or three hours to work with.

During the next step of the process, the Michigan researchers used a laser to remove DNA from the egg; a method borrowed from human in vitro fertilization. Next, the team devised a new, more efficient way of inserting the donor cells into the egg.

The tricky part was finding a way to get into the egg,” Cibelli said. “We used the same entrance that sperm uses. There was only one spot on the egg, and we had to find it.”

You can find more information in the most recent issue of the journal Nature Methods.

The main author of the article “Novel Somatic Cell Nuclear Transfer Method in Zebra Fish,” is Kannika Siripattarapravat, a doctoral student in Cibelli’s Cellular Reprogramming Laboratory. Other authors include Patrick Venta, an associate professor of microbiology and molecular genetics, and C.C. Chang, a professor of pediatrics and human development.

‘Eat ‘um to beat ‘um – Lion hunt in the Bermudas

Bermuda‘s first Lionfish Tournament resulted in just four participants returning with lionfish for the weigh-in. Although this might sound disheartening, it is actually happy news for Lionfish project leader Chris Flook of the Bermuda Aquarium, Museum and Zoo since it indicates a relative scarcity of lionfish in Bermuda waters.

Lionfish is an invasive species in the Caribbean where it lacks naturally predators and multiplies uncontrollably. In the Bahamas, female lionfish spawn twice a month. Lionfish Tournaments like the one just held in the Bermudas is a way to boost public awareness and decimate the number of lionfish in the Caribbean. A Lionfish Tournament held in the Bahamas a few weeks ago resulted in the catch of about 1,400 lionfish.

If we’d caught 1,000 fish it would have been very concerning, because it means it’s happening here like everywhere else,” Flook explained. “It means we may be ahead of the game and are potentially managing the population here in Bermuda.”

However, Flook also said that one of the reasons why not many fish were caught Bermuda’s Lionfish Tournament could be that they were hiding in deep waters following the storm surge of the recent Hurricane Bill and Tropical Storm Danny.

Mr. Flook began the Lionfish Culling Programme last year to encourage divers and fishermen to hunt down the species. Organised by environmental group Groundswell, the ‘Eat ‘um to beat ‘um’ event also aimed to show how invasive lionfish can be utilized as a food source.

“I think everybody who tasted it was very for it. It’s a great tasting fish,” said Flook, as Chris Malpas, executive chef at the Bank of Butterfield, cooked up samples of speared lionfish at Pier 41.

The tournament has got the message out and so now hopefully people might start asking for lionfish in restaurants and fishermen will bring them in rather than throwing them overboard.

By eating lionfish we will take the pressure off some of our commercial fish. Every one you take is one less eating our juvenile fish,” said Flook.

If you want to know more about spearfishing lionfish in Bermudas, contact the Bermuda Aquarium at 293-2727 ext. 127, or the Marine Conservation Officer at 293-4464 extension 146 or e-mail lionfish@gov.bm. The Marine Conservation Officer should also be contacted if you see a lionfish in Bermuda waters.

Rare fish threatened by the aquarium trade, says Thai dive instructor

According to Thaphol Somsakul, a civilian dive instructor with the Navy, rare marine species like Giant stingray and Ronin are becoming harder to find in their regular Thai habitats as they are sold to aquariums by fishermen.

Thaphol said he became suspicious after noticing rare species with distinctive marks at various trawler piers, and then seeing them later in aquariums.

The decrease in number of these species coincides with the increase in the number of new aquariums opening, as well as in the number of rare species on display,” he said, citing his own experience and reports from fellow divers. “I interviewed fishermen who all said those rare species were trapped in their nets by chance.”

Unlike protected or endangered species, rare species are not protected by Thai law. A one year joint project by the Navy, PTTEP, and the NaturalResources and Environment Ministry is however scheduled to inspect 20 sites in the Gulf of Thailand and the Andaman Sea to locate coral reef sites and gather information that will be used in a coming reef conservation project.

Reef recovery more complex than presumed, researchers say

In 1998, the gobies vanished from a section of the Great Barrier Reef as the corals became bleached. The corals have now re-colonized the bleached areas, which are located just of Orpheus Island, but the gobies haven’t returned. This lack of goby fish is puzzling Australian researchers, who had assumed that the gobies would return as soon as the corals bounced back.

Professor David Bellwood from James Cook University says the goby’s failure to repopulate the coral is disturbing, and that it may be an indicator that fish will not return to damaged reefs as fast as first thought.

“What’s happening is they’re not bouncing back, they’re not coming back as fast as we’d expect”, says Bellwood. “These gobies only live for a few weeks – you’d expect them to be turning over very, very fast and they become like an indicator of how the future might be. The reef may never be the same ever again – it’s going to be different, we may have a reef but it’s not going to be like the one we remember and it’s more variable and more unpredictable than we thought.”