Alaska's Lake Monster?: a large shark moving into fresh water could be answer

Big Foot.  Nessie.  Many regions of the world have there local monster animal legends.  Persistent folklore often invites the curiosity of scientists who wish to determine once and for all what is fact and what is fiction.  They do so because of the belief that where there's smoke there just might be fire.

In Alaska, at Lake Lliamna, there were rumors of a monster lurking about in the dark cold water. Scientists had debated the possibility that a Pacific sleeper shark, or sharks, had entered the lake. There had been anecdotal sightings of what could possibly have been a sleeper shark but there has not been any definitive, scientific proof.

This past Wednesday, a reported sighting of a sleeper shark in a similar, nearby lake has added some additional weight to the theory.  As reported in the Alaska Dispatch, "Chris Babcock of King Cove, Alaska, spotted something in the shallow water of the King Cove Lagoon, a lake of brackish water. Closer inspection revealed a Pacific sleeper shark rolling and thrashing around. The shark's antics were filmed and posted on YouTube (see video below). According to Babcock, the fish approached him when he entered shallow water, but later moved to deeper water." 

The shark's behavior was considered a bit unusual - but perhaps not.  That is to say, there is a lot that marine experts don't know about these sharks.  They can reach a length of 20 feet and weigh upwards of 4 tons.  That's a big shark by any standard.  In addition to being predators, they are thought to be major scavengers, clearing the ocean bottom of dead animals as they sink into the cold depths, but sleeper sharks caught accidentally in nets have also been found to have other freshwater fish including salmon in their stomachs.  Hence, the possibility that sleeper sharks are able to venture into freshwater or brackish lakes, perhaps drawn in by the opportunity to feed on large freshwater fish.

But how long can they survive in freshwater?  Is there a pattern or migratory cycle to their appearances in lakes?  Is it seasonal, based on weather or temperature changes, or are they following the migratory or breeding patterns of other prey species?  Scientists like Bruce Wright of the Aleutian Pribilof Island Association would like to answer those questions by tagging and tracking sleeper sharks, as is done with other shark species worldwide.

Some marine scientists think that sleeper sharks could become a major predator in Arctic waters due to climate change.  With warmer water temperatures melting greater amounts of sea ice, animals like seals and polar bears are spending more time in water.  Some caught sleeper sharks have been found to have seal and even polar bear remains inside, so this slow-moving predator - that catches its prey with a strong vacuum motion of its large mouth, biting with its teeth to get down what it couldn't swallow whole - could have an impact of the balance in the Arctic ecosystem.

Is the Pacific sleeper shark the "lake monster" of Alaskan folklore?  Seems reasonable enough.  The closely-related Greenland shark has been put forth as a candidate for Scotland's Loch Ness resident sea monster, so perhaps someday we will have definitive proof that monsters do exist.  They just might end up a bit tamer than our imaginations have conjured up over the years.

Source: Alaska Dispatch

Red-Tailed Hawk: predatory birds are ever-present and vital to nature's balance

Predators play an important role in maintaining balance within nature's ecosystems. When we think of a predator, we often think of large animals like sharks, lions, or wolves. But predators come in all sizes. In fact, any animal that feeds on another animal can be considered a predator and that predation helps to keep the populations of its prey healthy by weeding out the sick or aged, and keeping numbers in check by counteracting high reproductive rates.

In fact, for animals that are prey to several different kinds of predators, a high reproductive rate is nature's consolation prize of sorts for being the unwitting prize of a predator. In the seas, plankton, krill and many species of small baitfish have high reproductive rates as they are a food source for many different predator species ranging from small reef fish to massive whales. And on land, many rodent species - rats and mice in particular - reproduce in great numbers to offset predation from everything from coyotes to hawks.

Speaking of predatory birds, their roles are very similar to predators like sharks. Two roles actually, depending on the bird. Sharks play a critical role as scavengers and there are vultures and buzzards that play a similar role. Sharks are also hunters and hawks and eagles follow parallel duties. To hunt, the predator needs an advantage and for hawks it can often be incredibly sharp eyesight combined with lightning speed.

In the Sioux Falls Argus Leader, writer Jerry Stanford writes of his admiration for the red-tailed hawk, a common predatory bird in South Dakota, "In mid-September, my wife and I traveled south of Sioux Falls to watch the ever-changing season turn from lush green to golden yellow. While enjoying the wonderful wide-open spaces, we managed to observe several majestic red-tails swirling in the deep blue-sky updrafts, sometimes to the point where the feathered acrobats disappeared among the billowing clouds. During our half-day jaunt, I was constantly reminded of the great bird's flexibility as it grabbed hold of invisible updrafts that somehow managed to help navigate the acrobat to where it wanted to go."

Stanford cites the writings over fifty years ago of Charles Flugum who identified the important role the hawk plays and the importance of not regarding them as a nuisance, "The role of hawks in the balance of nature is to counteract the dangerously rapid reproductive rate of mice and other rodents. It is sound conservation practice to protect all our hawks, except those individuals actually caught in the act of taking poultry. There has been some improvement in the attitude toward our birds of prey in recent years, especially in securing legislation for their protection. We have a long way to go, however, before an enlightened and aroused public will give these laws the support they need to make them really effective."

In Southern California, where I live, one doesn't have to go far, even within a suburban setting, to find an occasional hawk circling overhead. Hawks have adapted somewhat to the presence of human urban development - one pair of hawks became rather famous locally in New York for nesting on the side of an office building and raising a family, subsisting on the many rodents that live in the city. And I wonder how quickly we would be overrun by mice and rats if we were to be without these aerial rodent exterminators.

Predatory birds face many threats, even with conservation and protective regulations in place. Poisons ranging from lead shotgun pellets - consumed by eating prey which survived a previous encounter with a hunter - or fertilizers and insecticides, and even rodent poisons which would weaken or sicken a rat or field mouse, making it an easy target for a hawk. And then there are the direct, man-made threats from hunters, or poultry farmers protecting their birds And for large eagles, buzzards, or condors, there is the threat from coming in contact with high power electrical lines.

The relationship between predators and prey can sometimes be a bit like the classic chicken or the egg conundrum - which came first? Did nature evolve a predator to combat the population growth of a highly reproductive species or did the prey develop the ability to grow in great numbers to counteract predation? Such is the complexity of nature's ecosystems and we must be always mindful of the natural balance that occurs. One wrong step on our part and an ecological card castle can come crashing down.

Read Jerry Stanford's recollections of the red-tailed hawk in the Argus Leader.

Seychelles Shark Incidents: statistical anomaly put media and authorities in overdrive

Shark frenzy is in high gear once again - and not due to the sharks, but by the news media which can seem to have a taste for blood greater than any ocean predator I have encountered. Recently, in the Seychelles, two separate attacks by sharks on bathers have occurred within two weeks of each other. That by itself is statistically unusual. Add to that the fact that it has been several decades since the last shark-human incident in these Indian Ocean islands and you have the basic ingredients for a sensationalized story and a knee-jerk reaction on the part of the Seychelles authorities.

With the most recent incident - a young man attacked while snorkeling in shallow water - several news outlets are devoting airtime and print space to both, the human tragedy - the attack was witnessed from shore by the young man's newly wed wife - and the ensuing hunt that is currently taking place for the "killer" shark.

The news media is taking every guess, hypothesis, crackpot assumption, and misconception as facts in this attack - I have read it was a white shark (unlikely based on the multiple bites this latest bather received); a bull shark measuring 18 feet in length (a size which would be a modern miracle in marine biology); a "rogue" shark as the culprit (whatever that means, a well-worn rationale to try to explain what amounts to the normal actions of a large predator in its natural environment); and so on.

And then there is the reaction of the authorities, enlisting the aid of local fisherman to deploy hooked and baited longlines in an attempt to catch the specific shark responsible. Now, I can understand their need to be seen as taking some sort of definitive action. They have a tourist trade to protect and perhaps merely closing beaches won't instill confidence for their tourism compared with catching and killing the shark responsible. However, in the end, there will undoubtedly be many sharks and other large fish caught and killed as a result of the shark hunt. And maybe they will succeed in catching a shark that contains human remains, but that will guarantee nothing.

The one indisputable fact is that the ocean is not our playground; it is home to a range of marine life from brine shrimp to blue whales, and every time we dip our toes in the water, we are intruding in their space. Urchins will stick and sting rays sting when stepped on, sea jellies will fire their nematocyst stinging cells when bumped, and sharks will, on very rare occasions, mistake a human as potential prey. This isn't meant to marginalize or dismiss the human tragedy or the visceral impact when a person is attacked by any predator, on land or sea. But it is the one constant whether you are using the oceans for recreation, scientific study, or commercial gain.

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Sharks and Monochromacy: examining predator's limited color vision

It's a colorful world we live in. At least it appears that way. A red apple is not actually producing red light; it's absorbing other non-red light wavelengths and reflecting those wavelengths that we perceive as red. Our eyes have evolved to contain three types of color receptors that respond to certain light wavelengths - basically reds, greens, and blues - which puts us in the category of trichromats. Other animals are dichromats, having two color receptors, while many others have little or no color vision.

Why? Well, partly its evolution's adaptive radiation at work, where animals evolve certain traits or abilities to best respond to their environment and thereby enhance their chances for survival.

In the aquatic world, color can take on a different purpose as the water environment effects various wavelengths. Red wavelengths fade quickly - the underwater world is cast in a blue or green hue because these wavelengths - particularly blue - can travel further, deeper into the water column. So, if you are a predator, what works best in hunting prey? Having a full-range of color sensitivity or limited monochromatic vision that best matches your environment?

In a paper recently published in the natural science journal, Naturwissenschaften, researchers from the University of Queensland, Australia, (including my niece, Dr. Susan Theiss) studied the color vision capabilities of 17 different species of sharks, from small bottom-dwellers like the port jackson shark to open water species like tiger and bull sharks. In many cases, what they found was a monochromatic trend toward blue but with some interesting exceptions.

Juvenile lemon sharks have a greater sensitivity to red, perhaps because of the amount of time spent in shallow waters where a fuller color spectrum would exist. But as adults, they appear to lose that sensitivity as they move into deeper waters. Bull sharks, which can spend up to the first 5 years of life in shallow, brackish water areas, seemed to have a similar sensitivity to red but research has yet to show that they too become more monochromatic as they mature, although it is a distinct possibility.

Many skates and rays are trichromatic and, as these species are close cousins to sharks, it begs the question as to what evolutionary advantage monochromatic vision might provide sharks. Well, in a very unscientific observation, as a filmmaker I can concur with one of the prevailing theories: contrast. Many broadcast video cameras have viewfinders which can switch from color to black and white. With black and white, contrast is all you are left with, and many cameramen feel they are able to focus more accurately and even track the on-camera action better in black and white, as if the fullness of color becomes a visual distraction.

And perhaps that is what the shark needs: a greater sensitivity to high contrast derived from monochromatic vision which helps to discern prey from its surrounding background. Combined with their other electroreceptive capabilities like the Ampullae de Lorenzini and sensitive lateral line, sharks may have developed the most efficient form of vision for hunting, one that has evolved from its surroundings over millions of years.

Susan and her colleagues are continuing to study the color vision capabilities of various shark species. Its microscopic, exacting, and tedious work (sharks can't exactly cover one eye and read from an eye chart: EFPTOZ . . .), but with that knowledge we can gain a better understanding of shark behavior and how, as apex predators, they effectively contribute to a healthy marine ecosystem.

Read the entire paper on sharks' color vision in Naturwissenschaften.

Jumbo Squid in Oxygen-Poor Zones: new study shows ability to expand territory and evade predation

New research adds further insight into the ability for the Humboldt, or jumbo, squid to expand its territory and become even more of a destabilizing predatory influence along the coast of the Eastern Pacific. In the latest issue of Progress in Oceanography, researchers from the University of Lisbon, Portugal, and the University of Rhode Island, U.S., studied the squid's metabolic rates in water with different oxygen levels - duplicating the oxygen-poor environment found in waters several hundred meters deep and also the oxygen-rich environment of relatively shallower depths.

Dr. Ruis Posa, of Portugal's Center for Oceanography, posed the question, "Jumbo squid display oxygen consumption rates that are among the highest in the oceans. This high energy demand reflects the low efficiency of jet propulsion. So the question is how can they survive in these deep, cold and oxygen depleted zones?"

According to Dr. Rosa, from Portugal's Center of Oceanography, the squid displayed the ability to shut down its metabolism by as much as 80% in the oxygen minimum layer (OML). This enables the squid to find a safe haven during the day beyond the reach of many of its predators. During the night, the squid rejuvenates itself in shallower waters where its metabolic demands increase dramatically as it hunts for food using its jet propelled speed coupled with tentacles laced with tooth-lined suction disks.

As mankind continues to alter the marine environment, we are finding more and more areas of lower-than-normal or even near-depleted oxygen levels in the oceans, thereby providing the voracious Humboldt squid with the capability of expanding its range. An animal's territorial range can be maintained by a variety of factors, some of which are based on the quality of its environment and on the predators that help keep the population in check. With this newly studied metabolic ability, the Humboldt squid can utilize spreading OMLs to its advantage, avoiding predators during the day and causing havoc amongst commercially fished species at night.

Read the study in Progress in Oceanography. Read more about the study in BBC News. Watch video below from Google Earth/Ocean.

Sharks Win By A Nose: research details stereo olfactory ability

To be the efficient predators and scavengers that they are, sharks have an amazing array of sensory functions - from smell, sight, hearing/vibrations, to sensing electrical impulses. Working in coordination or in a sequence, these capabilities give sharks the edge to survive whether cruising an ocean reef or plying the wide open oceans hundreds of miles offshore.

Now, new research by the Woods Hole Oceanographic Institution (WHOI) and the University of South Florida shows how shark's sense of smell is even more refined than previously thought, by sniffing scents one nostril at a time - a sort of stereo smell-o-vision!

In a recent press release, WHOI researcher Jelle Atema said, “The structure of an odor plume is chaotic and not at all coherent. It’s just like what you see with the Gulf oil spill, which is essentially a gigantic odor plume. The plume breaks up into pieces, floats to different levels and gets transported in a current.”

By determining which nostril detects the odor first, the shark is able to determine a direction, much like our stereo hearing allows us to determine direction based on which ear detects a sound first or with greater intensity. The researchers confirmed this with tests using smooth dogfish, a small shark local to New England waters, and squid odor as an attractant.

But as Atema said, odors are transported rather haphazardly by currents, so sharks bring another sensory ability into play to help steer them in the right direction: the lateral line. This sensitive organ along a shark's body can detect faint vibrations in the water - vibrations like those given off by an injured fish or by the movement of water currents. Previous studies by Atema and fellow colleague Jayne Gardiner of the University of South Florida, showed that sharks use the lateral line to detect the direction of subtle currents - much like sensing wind on the hair of our bodies but with much, much greater sensitivity.

Combining these sensory abilities - stereo olfactory perception and lateral line vibrations - sharks are able to determine a direction and follow an odor to its source. “Inspired by odor, sharks also look for current,” Atema said. “The two together is what makes them so efficient.”

One more reason to look at sharks with awe and fascination and not ignorance or fear.

Read the Woods Hole press release.

Colossal Squid: study suggests its not the aggressive monster of myth

There is so little that we know about the deepest recesses of the oceans. Our ignorance and our fears often unleash our imagination to conjure up the worst of monsters - not just in today's sci-fi movies, but for centuries man has felt that there are unspeakable horrors lurking in the ocean's blackness.

As many of my readers know, in March I was on assignment for National Geographic to film the jumbo squid, or Humboldt squid, in Baja, Mexico. Working with Scott Cassell of the Undersea Voyager Project, who has spent many years encountering and studying the jumbo squid, this was my first opportunity to meet these voracious predators on their home turf. I soon learned these are very aggressive animals that will attack just about anything if they think it means a potential catch.

There are actually three large species of squid - each with a name that one-ups it's smaller cousin. The jumbo squid, followed by the rarely seen giant squid, and topped by the even rarer colossal squid. Each squid is considered a powerful and aggressive predator based on what evidence was available on any of the species combined with anecdotal evidence such as bite markings on large whales, like sperm whales who, as one of the larger squids' natural enemies, are suspected of diving deep and hunting large squid using echo-location.

It is now being suggested in a recent scientific study, that the colossal squid, the rarest of the rare and the world's largest invertebrate, may not be as aggressive as our imaginations lead us to think. Reported in the BBC's Earth News, the study by Dr. Riu Rosa of the University of Lisbon and Dr. Brad Seibel of the University of Rhode Island suggests that the colossal squid just may turn out to be a slow moving, lies-in-wait ambush predator. This theory is based on metabolism studies of related squid species and then extrapolating those findings to account for the colossal squid's size, in addition to other factors, such as the cold temperatures in which the squid lives.

"Our findings demonstrate that the colossal squid has a daily energy consumption 300-fold to 600-fold lower than those of other similar-sized top predators of the Southern Ocean, such as baleen and toothed whales," says Dr Rosa.

Studies of trace isotopes in tissues samples from the few dead specimens of colossal squid that have been found, show evidence of one of the squid's primary food sources: the arctic toothfish. Based on that, the study determined that an 11-pound (5 kg) toothfish could nourish a 1000-pound (500kg) colossal squid for up to 200 days. It all makes reasonable sense. Given that the deep depths contains less large scale bio mass than in shallower, sunlight-bathed waters; a large predator would need to maximize its use of whatever it could catch, and a lower metabolism - which can equate into less activity - would be one way to accomplish that.

Nonetheless, based on the few specimens that have been examined, the colossal squid is a formidable source of nightmares and mythological legends. It can reach a length of possibly 50-feet (15m) from the tip of its large mantle to the end of its tentacles, equal in length to that of a sperm whale. And whereas the jumbo and giant squid have small teeth that ring each sucker disk on its arms and tentacles, the colossal squid has large, swiveling hooks to latch on to their prey. Yikes!

We know so little about the ocean depths. It has been said that we have more data about the backside of the moon than we do about the oceans depths that make up the vast water volume of our blue planet. The more we commit ourselves to studying it, the more we will learn what is happening to our fragile marine ecosystems and what we should do to protect them. And along the way, a few nightmares might get dispelled, a few legends might get rewritten.

All the same, I'll sleep with the light on tonight.

Read the complete article in the BBC Earth News.

Species Migration: Humboldt squid - a hungry predator moves northward

When we think of "invasive species," one might think of the example of the Lionfish that has invaded Florida waters due to being initially released from a home aquarium. Or perhaps algae, seaweeds or other parasites or bacteria that get discharged from the bilges of freighters and tankers, thousands of miles away from its point of origin.

But there is also species migration, wherein a species enters into a new region sometimes because of a change in its typical prey diet or because of a change in its environment - such as temperature change.

Both factors enter into the migration that has occurred over the past several years by the Humboldt Squid - a large and particularly voracious predator.

I have had the pleasure of working on several potential projects with Scott Cassell, CEO of the Undersea Voyager Project and one of the leading experts on Humboldt Squid, a distinction borne out of his having spent more time face-to-face with these creatures than anyone else. Scott has made the rounds of many news programs to express his concern with the recent regional habitat changes of the Humboldt Squid and what it represents to the balance of the marine and terrestrial ecosystems and even the safety of humans.

The Humboldt Squid is a large deep water predator, typically found along the west coast of Mexico and South America. But over the past several years, there have been two major changes that have impacted this animal. One factor: the overfishing of shallower-water predators that either feed on the squid or on the squid's food supply - thereby establishing territorial boundaries based on depth. Without these shallower predators, the squid can and has begun to roam in search of food. The second factor: increasing water temperatures which have allowed the squid to migrate up the coast and as far north as Washington and Alaska. Another possible variable is that changing temperature and acidification upwardly expands the low-oxygen water column that the squid seems to favor.

Moving into shallower water is of concern to Scott as that can increase the likelihood of a Humboldt Squid encountering curious divers or even swimmers. This past summer, divers were regularly seeing Humboldt Squid during night dives at La Jolla, CA, near San Diego. Whether on the hunt or simply being curious, these animals are not to be taken lightly - they have powerful suckers, a beak that can break bones, and the speed and strength to drag a diver around in the depths.



The squid's migration northward is also of concern because of its ability to disrupt the food supply for other animals. They have been cited by some as being responsible, along with commercial fishing, for a reduction in the northwest population of salmon. And this can impact other animals that depend on this particular food source. As an example, Grizzly Bears count on the fat-rich salmon for building up their stores to survive the winter.

There have been other invasive species migrations due to changing ocean temperatures; in particular, several jellyfish species that have moved into both Northern Atlantic and Pacific waters and doing considerable damage to commercial fishing or aquaculture operations - their stinging tentacles spoil the catch.

But the Humboldt Squid is just not someone you want to bump into in the middle of the night. He's just doing what evolution has taught him to do, but this is one critter than can really give you the willies!