Archive for the ‘Fish’ Category

Federal biologist Jay Orr never knows what’s going to come up in nets lowered to the ocean floor off Alaska’s remote Aleutian Islands, which separate the Bering Sea from the rest of the Pacific Ocean. Sometimes it’s stuff he has to name.

The National Oceanic and Atmospheric Administration biologist is part of a group that uses trawl nets to survey commercially important fish species such as cod in waters off Alaska. Sometimes those nets come up with things no one has seen before.

With co-authors, Orr has discovered 14 kinds of new snailfish, a creature that can be found in tide pools but also in the deepest parts of the ocean. A dozen more new snailfish are waiting to be named. Additional species are likely to be found as scientists expand their time investigating areas such as the Bering Sea Slope, in water 800 to 5,200 feet deep, or the 25,663-foot deep Aleutian Trench.

“I suspect we are just scraping the top of the distributions of some of these deep-water groups,” Orr said from his office in Seattle.

Orr and his colleagues measure the abundance of rockfish, flatfish and other “bottom fish” for the Alaska Fisheries Science Center, the research arm of the NOAA’s National Marine Fisheries Service. The center studies marine resources off Alaska and parts of the West Coast.

Five boats with six researchers each surveyed Alaska waters in late June. The teams trawl on the Bering Shelf every summer and in either Aleutian waters or the Gulf of Alaska every other year.

Their findings on fish abundance are fed into models for managing fish populations.

The scientists put down a 131-foot trawl net that captures whatever is along the ocean bottom. A ton of fish is a standard sample. Along with fish, they get clues to the seafloor habitat. Sponges, for example, indicate a hard seafloor, or substrate.

Fifteen years ago, research biologist Michael Martin suggested a small modification: a net just 2 to 3 feet wide at the front of the trawl net.

“We realized we didn’t have a really good picture of the substrate that we were trawling over, and we figured we were missing some things in the big meshes that the larger net had,” Orr said. “So one of the other guys here decided to put this little net on, mainly as a means to see what the substrate looked like.”

On one of the first hauls, the small net returned with a variety of small, soft-bodied fish, including snailfish, that likely would have fallen out or gotten mashed in the main net. Orr took a look and knew they had found something different.

As someone who studies fish, “I sort of knew what I was looking for and what was known out there,” he said. “The first ones that came up, I saw them right away and said, ‘We don’t know what these are. These haven’t been named.'”

Snailfish have no scales, feel gelatinous and look like fat tadpoles. Aristotle described a Mediteranean variety found in ancient Greece as “sea slugs.”

Many fish have pelvic fins on their bellies, just behind the gills. Most snailfish species, instead of pelvic fins, have a sucking disc that they use to cling to rocks.

Orr identified some new varieties that did not have a sucking disc. Another had a hardened bone in its head. Another had a projecting lower jaw. Others varied by shape, color or body parts, such as vertebrae.

“Nearly all of them have genetic characters that distinguish them, too,” Orr said.

He has wide latitude for giving new species both common and Latin names. A red, white and black snailfish with a big, bulbous nose struck him as funny-looking. He gave it the common name of “comic snailfish” and the Latin name Careproctus comus, after Comus, the god of comedy in Greek mythology.

Snailfish made headlines in 2014 when researchers recorded them swimming nearly 27,000 feet, or more than 4 miles, below the surface in the Marianas Trench, making them the deepest-dwelling vertebrate on the planet. The Marianas Trench is about 200 miles southwest of the Pacific island of Guam and is known as the deepest part of the world’s oceans.

A critical part of the work is on the species his agency actively manages. Orr helped distinguish the northern rock sole, which spawns and grows differently than other rock sole. Fishing at the wrong time could disrupt a population important to the seafood market.

“Ultimately we’re managing an ecosystem,” Orr said. “It’s really important to know what each of the elements are.”

http://bigstory.ap.org/6f677b05f94b4031b82b1c41aaab835b

Advertisements

by Jamie K. White

Can your pet fish recognize your face? A new study says, Yes, it probably can.

Researchers studying archerfish found the fish can tell a familiar human face from dozens of new faces with surprising accuracy.

This is a big, big deal. It’s the first time fish have demonstrated this ability.

Think about it: All faces have two eyes sitting above a nose and a mouth. And for us to be able to tell them apart, we need to be able to pick up the subtle differences in features.

We’re good at this because we are smart, i.e. we have large and complex brains. Other primates can do this too. Some birds as well.

But a fish? A fish has a tiny brain. And it would have no reason in its evolution to learn how to recognize humans.

So this study, published Tuesday in the journal “Scientific Reports,” throws on its head all our conventional thinking. It was done by scientists at University of Oxford in the U.K. and the University of Queensland in Australia.

And, for us, it raises many, many questions:

Does this mean my pet goldfish knows me? Do fish recognize each other? CAN DORY REALLY FIND NEMO?

To find out more, we talked to Dr. Cait Newport, a research fellow in Oxford University’s zoology department and co-author of the study.

What were the scientists trying to figure out?

The scientists wanted to know how well animals with simple brains do with facial recognition. A fish was a good choice. Their brains lack the section that we use for facial recognition. That made them perfect as subjects for an experiment to see if simple brains can perform complex tasks.

What’s an archerfish?

It’s a species of tropical fish. They spit jets of water from their mouth to knock down insects from branches. They’re the sharpshooters of the animal kingdom.

Why did scientists use archerfish?

Archerfish can indicate a choice clearly (the spitting) whereas other fish cannot. “There is no ambiguity in where they are shooting,” Newport said.

How did the experiment work?

Scientists presented the fish with two images of human faces and trained them to choose one by spitting their jets at that picture.

Wait, hold up. How do you ‘train’ an archerfish?

The old, time-tested way. Bribe them. When they spit at the image the scientists wanted them to spit at, they were rewarded with a pellet of food, Newport said.

How long did that take?

In some cases, only a few days. In others, up to two weeks. “Something like 60 to 90 trials,” Newport said.

How many people did it take?

A total of four (really smart) people: Newport and her co-authors Guy Wallis, Yarema Reshitnyk and Ulrike E Siebeck.

What did they do?

They presented the fish with the picture of the face they wanted the fish to learn and a bunch of new faces. Up to 44 new ones. The fish were able to pick the familiar face correctly 81% of the time.

Impressive. And then?

The researchers decided to make things a little harder. They took the pictures and made them black and white and evened out the head shapes. You’d think that would throw the fish for a loop. But no, they were able to pick the familiar face even then — and with more accuracy: 86%!

What will they test next?

They plan to test for other recognitions beyond just faces, Newport said.

Do fish only recognize human faces?

Humans use lots of devices to recognize people, including social cues. “Fish are not doing this,” Newport said. “For them, they are just looking for patterns.” That would answer the question whether Dory could find Nemo.

Finally, for the big one: Does my pet fish know me?

Possibly.

“There’s something like 30,000 species of fish. A blind fish is not going to be able to do this, sharks are fish and they can see color — so maybe,” Newport said.

Then she shared this observation.

When strangers walk into her lab, the fish “act skittish,” she said.

“When I walk in, they start spitting at me — many cases right in the eye.”

How’s that for accuracy?

http://www.cnn.com/2016/06/07/health/fish-human-face-recognition-study-trnd/

If you have a goldfish, and you are kind of over that goldfish, to the point where you are now wondering whether it might be best to set that goldfish free, please rethink that decision.

That’s the request from the Alberta government, which is trying to get Canadians to refrain from dumping out their fish tanks into ponds. Because those ponds are filling up with those discarded goldfish, which are getting really, really big in the wild.

Or, as the CBC notes: “Goldfish the size of dinner plates are multiplying like bunnies.”

“It’s quite a surprise how large we’re finding them and the sheer number,” Kate Wilson, aquatic invasive species coordinator at Alberta Environment and Parks, told the broadcaster.

According to CBC News:

In one case, the municipality of Wood Buffalo pulled 40 of the domestic fish species from a stormwater pond.

“That’s really scary because it means they’re reproducing in the wild, they are getting quite large and they are surviving the winters that far north,” said Wilson.

“Their size is limited in the tank, but when you release it into the wild, that doesn’t exist anymore,” Wilson told The Post.

Like other species of carp, the domestic goldfish Carassius auratus will basically keep growing as long as water temperatures and food resources support it. There are obviously limits — you’re not going to accidentally create fishzilla if you overfeed your goldfish — but given a big body of water with tons of food and warm summers, a fish is bound to get supersized.

Then you end up with a bunch of goldfish bruisers competing with local fish for resources, and you better believe the fish you flushed will give native species a run for their money. Plus, some scientists say, goldfish feces might help support certain types of algae, leading to algal blooms that further disrupt the eco-system.

The CBC reports that a campaign designed to curb this trend, called Don’t Let It Loose, will “focus on educating Albertans about the dangers of releasing domestic fish into nature.”

If people are dumping their aquariums, Wilson explained, they’re also dumping the water it holds, which can carry disease and parasites. What’s more, the goldfish can survive in poor water conditions, she said, and “could be competing with our native species for both food and habitat.”

sn-heliocoprion

An ancient fish that sported a saw blade-like whorl of serrated teeth—and was long presumed to be a member of the shark family—actually belonged to a different but closely related group, a new study suggests. Members of the genus Helicoprion were first described in 1899, but fossils have been notoriously incomplete, with most including only spiral groupings of teeth. Although some fossils have also preserved hints of cartilaginous tissue, none have included the braincase or postcranial parts of these fish. Accordingly, scientists never came up with a convincing idea of what these creatures looked like, with some teams suggesting the whorls sprouted from the nose like an elephant’s trunk, and others placing toothy appendages on the creature’s tail, dorsal fins, or drooping from the lower jaw. Now, an x-ray CT scan of a particularly well-preserved fossil unearthed in Idaho in 1950—one that includes 117 teeth, the cartilage on which they were attached, and part of the upper jaw—reveals that the whorl resided within the animal’s lower jaw (artist’s concept above), researchers reported in Biology Letters. The size and shape of the upper jaw fragment suggests that the creature was about 4 meters long, with some other species in the Helicoprion genus measuring almost twice that length. The arrangement of tissues in the animal’s lower jaw, including those previously hidden by the rock that entombs them, definitively shows that Helicoprion is not a shark, the researchers say. Instead, the genus is nestled firmly within a group of cartilaginous fish known as chimaera, a lineage that includes species commonly known as ghost sharks and ratfish.

http://news.sciencemag.org/sciencenow/2013/02/scienceshot-ancient-fish-sported.html?ref=em

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

121205200057

 

Carp stored in large tubs at Czech Christmas markets align themselves in the north-south direction, suggesting they possess a previously unknown capacity to perceive geomagnetic fields, according to a new study published December 5 in the open access journal PLOS ONE, led Hynek Burda from the University of Life Sciences (Prague), Czech Republic and colleagues from other institutions.

Their study included over 14,000 fish in 25 markets, and the majority of these fish were found to align themselves along the north-south axis. The fish were accustomed to human onlookers, and street lights and other potential disturbances seemed to have no effect on the orientation of the fish.

In the absence of other common stimuli for orientation like light, sound or the flow of water, the authors suggest that the fish most likely align themselves to geomagnetic cues.

http://www.sciencedaily.com/releases/2012/12/121205200057.htm

 

The mass death of fish in a lake near Hamburg has been blamed on swimmers’ urine causing an algal bloom that has poisoned the water.

Around 500 dead fish have been found in the picturesque Eichbaum lake near the northern port city, which attracts bathers in the summery weather. But now it seems those pleasure-seekers have blood on their hands.

“Swimmers who urinate in the lake are introducing a lot of phosphate,” Manfred Siedler, spokesman for the Hamburger Angling Association (ASV), told Bild newspaper. “We’re calculating half a litre of urine per swimmer per day.”

Phosphate contributes to a build-up of blue-green algae in the water, playing havoc with the lake’s eco-system and apparently poisoning the fish. According to Bild, authorities have already tipped some 148 tonnes of anti-phosphate agent Bentophos into the water, at a cost of €516,000, but to little effect.

The Local understands that there has also been a longstanding feud between the anglers and the bathers over the lake.

Bathers are currently banned from the lake due to the high levels of algae, but the city’s Urban Development and Environment Authority (BSU) is working to fight it and re-open the lake.

The BSU believes that the fish deaths are not particularly unusual, and have been caused by a combination of natural causes and ice-skaters, rather than pee.

“The ice-skaters make a noise that wakes the fish out of hibernation,” BSU spokeswoman Kerstin Graupner told the Local.

“Then they can’t breathe and freeze. That’s a very common phenomenon.”

She underlined that though the fish have only been found in the past two weeks, they must have been dead for some time, judging by the decomposition.

BSU has since called in Hamburg University to test the pee-death theory, and says that apart from the high level of algae, the water is clean. “It is very rich in fish,” Graupner added.

But according to Bild, the first water tests are not encouraging – with a pH level of 8.7 (as opposed to the neutral 7), the lake is very alkaline.

Scientists have reportedly also found anabaena algae blooms, unusual at this time of year, which produce anatoxin-a. This causes the lake’s ammonium to change into the poisonous ammonia, which restricts the fish’s breathing.

 

Some of the fish in New York’s Hudson River have evolved resistance to several of the waterway’s toxic pollutants. Instead of getting sick from dioxins and related compounds including some polychlorinated biphenyls, Atlantic tomcod harmlessly store these poisons in fat.  However, it may not be so good for the higher-ups in the food chain.

http://www.wired.com/wiredscience/2011/02/fish-toxins-environment/

http://www.wired.com/wiredscience/2011/02/fish-toxins-environment/