Archive for the ‘shark’ tag
Diver-citizen scientists help find out why there has been a recent increase in the number of Sevengill Sharks spotted in the San Diego area
The first thing the divers noticed upon reaching the bottom was that there were absolutely no fish—anywhere. The lighting, also being strange, lent everything a deserted, eerie feel. But, says diver Mike Bear, “We continued deeper into this spooky, yellowish-green ‘ghost forest’ with its odd, dearth of fish—failing to make the obvious connection in our minds: where had they all the fish gone and why? The previous week, this same area was overflowing with life. Sometimes the fish sense something you don’t.”
Bear and diving buddy Dave Hershman had just entered the water off Point La Jolla. Swimming eastward, separated by about 12 feet of water, quite suddenly a long dark shadow materialized between them, “moving at a good clip,” says Bear. It took a couple of seconds for him to register that this was a fast-moving shark. “By the time he had pulled slightly ahead of me, I saw the characteristic long tail of the Sevengill pass before my face, and from a couple of feet recognized the species.”
What exactly is the Sevengill shark? Filmmaker, diver and founder of the Sevengill citizen science counting project Barbara Lloyd says, “Well, here’s the boring response to that question—scientifically speaking it’s officially known as the Broadnose Sevengill shark, Notorynchus cepedianus, and it’s the only existing member of the genus Notorynchus in the family Hexanchidae!”
This fairly large shark grows to about 11 feet, is speckled with gray or brownish spots, and has only seven gills on each side, which distinguishes it from the Bluntnose Sixgill shark. The Sevengill lives in tropical to temperate waters excepting for the North Atlantic Ocean and Mediterranean Sea.
With this post coinciding with Discovery Channel’s Shark Week, the more important question might be—have there been any attacks, since such a large predator inhabits these shallow near-shore waters? “Only three suspected attacks have been documented in the last fifty years,” says Lloyd, “with the most recent being in New Zealand in 2009.” They do get aggressive when feeding, mating, are provoked, and interestingly enough in aquariums. “Prior to that the Shark Attack File shows that there have only been five since the 17th Century.”
Lloyd and Bear began the Sevengill Shark ID Project in 2010, after hearing numerous reports of local divers encountering them, reports that had not previously surfaced. “I had been diving regularly in the San Diego area since 2000, averaging about 100 dives per year,” says Bear, “mainly in the area of La Jolla Shores, La Jolla Cove, Wreck Alley and Point Loma, as well as being actively involved in the San Diego diving community. I do not recall hearing any diver reports of encounters with Sevengill sharks much before 2007—and then suddenly we began hearing the first reports from local divers,” he notes.
The project website began as a simple spreadsheet which allowed local divers to log their encounters without photos. From there it developed into the site you see today, which uses photographs and a pattern recognition algorithm to ID individual sharks. The motivation was to answer the scientific question: why was there an apparent increase in encounters between divers and this species from 2007 onward?
Dr. John Hyde a marine biologist with the National Oceanic and Atmospheric Administration in San Diego wonders if the answer to that question might just be that it is a combination of more Sevengill sharks congregating in the area, and more divers in the water. “Overall we don’t have a good sense for changes in abundance of Sevengill sharks, but it is likely that they are increasing in number since the 1994 moratorium on nearshore (within three miles) gillnet fisheries in California.” The nearshore gillnet fishery had a significant effect on abundance of many fish species, especially sharks and rays, both as direct mortalities and indirectly by removal of prey items. Hyde adds, “This coupled with increasing numbers of recreational divers, cheaper and better underwater camera systems, and increased awareness of these sharks through social media has led to better documentation of their presence.” Though sevengills are fairly common these days, especially in bay and nearshore regions, there is still a lot of research to be done.
“We want to know why sevengills have been attracted to the La Jolla area over the past five years,” says Bear. “Is it the ocean conditions, changing water temperature, has the location just developed into the ideal nursery or pupping ground, or is it particularly mating-related? There may be an increase in prey, or it could be a combination of a number of these?”
The project has amassed a sizable database of still photographs and video, but they are still in the early stages of data collection and evaluation, and have not published any results yet. Barbara Lloyd has had some success using the pattern recognition algorithm to identify individual sharks.
For all, the most sublime Shark Week sensation would also be the most benign—to be able to dive with these magnificent predators, to be in their presence as they glide majestically by.
Are you a diver who lives in the San Diego area? Help the Sevengill Shark ID project answer their questions! Visit the project page on SciStarter to sign up and learn how to enter your sightings according to the specified protocols.
It’s Shark Week! And that means we’re lining up shark themed citizen science projects that you can participate in. Sign up for our newsletter to know which projects are being featured and watch this space for more blog posts!
That’s right–it’s the moment you’ve all been waiting for. It’s Shark Week, and SciStarter has a slew of projects for you to try out. Let’s see if you bite. Whether it’s fascination or fear, the sight of a shark makes our hearts skip a beat. Thanks to these featured citizen science projects, that sight can also contribute to shark conservation!
Increasing protection for sharks requires information about local populations. Provide data about sharks you see while diving or snorkeling.
Sevengill Shark Sightings
The Shark Observation Network invites Southern California divers to report and submit sightings of Sevengill Sharks, a species whose numbers are seemingly on the rise in the waters off San Diego.
The Great Eggcase Hunt from Shark Trust
Hunt for empty eggcases that have been washed ashore to help researchers locate potential shark and ray nurseries. This generates important data for researchers and conservationists working with sharks, skates and rays around the world.
New England Basking Shark Project
The New England Coastal Wildlife Alliance invites boaters, fishermen, and divers to report and share sightings of basking sharks to help scientists monitor the local population and better understand their migration patterns.
ECOCEAN Whale Shark Photo-identification
Upload your own shark photos or identify sharks in existing photos using this visual database of whale sharks!
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This digest of SciStarter Weekly Featured Projects was curated by Jenna Lang. If you’d like to see your project featured in our digest, e-mail firstname.lastname@example.org
More Gills or Eyes? The Purported Increase of Sevengill Shark Populations off the Coast of San Diego
Emerging technologies have a profound effect on how citizen scientists conduct their work. An underwater creature of ancient lineage helps to tell this modern story of technology’s importance to citizen science. Notorynchus cepedianus, the sevengill shark, of the ancient Hexanchidae family (cow sharks), features seven gill slits and a single dorsal fin, giving a prehistoric visage to this predator. Despite its uncanny appearance, this shark is one that has demonstrated little aggression toward humans, with fewer than five wild attacks accounted for since the 16th century.
In fact, divers have been increasingly encountering these creatures off the coast of San Diego. Harmless as these encounters are, they are spectacular and haunting, as Michael Bear, founder of the Sevengill Shark Tracking Project, would tell you. In the summer of 2009 he experienced the sevengill himself, after hearing rumors of its increased presence in the San Diego coastal area, when a giant seven-foot long (2.1 meters) sevengill glided between him and a dive-buddy. Describing that moment, Bear says that, “it is a humbling experience being in the presence of one of these large, apex predators––they have a grace and a majesty about them that is unforgettable.” But are these encounters an indicator of increasing sevengill populations or a product of increased numbers of divers––or perhaps divers with attentive eyes?
For many years few sightings were reported, but more anecdotal reports began to trickle in, and, Bear tells us, the “period that we really began hearing a significant increase in reports was 2009-2010.” Bear wanted to know more (and for good reason). The sevengill is a high-order or apex marine predator and therefore may be important to ecological structure, interactions, and ecosystem management (Williams et al., 2011 and 2012). In 2010 Bear’s project began to take shape.
The Sevengill Shark Tracking Project is a citizen science effort to collect baseline population data on the sevengill. Though it started out small, the project has grown, partnering with the Shark Observation Network. Now a single global database aggregates data on sightings to help determine baseline population information. Though a study of this kind can take many years, Bear’s project already has important insights for citizen science projects, especially in the use of new technologies.
Bear has developed the Sevengill Shark Tracking project’s smartphone app, called “Shark Observers.” It’s available for Android devices and allows divers to log sightings once they’ve surfaced and, presumably, dried off. While this particularly benefits sevengill tracking, the application actually allows users to submit logs for any kind of shark encounter to the Shark Observation Network database. This application can be downloaded through Google Play.
In addition to the app and database cataloguing the date, time, water temperature, and sightings––with separate databases for photographic and video recordings—the project has also started to use pattern recognition technology to identify individual sharks. This is an inexpensive alternative to costly and labor-intensive shark tagging.
With the I3S pattern recognition algorithm, which is also used for mapping star patterns on Whale Sharks, the sevengill project uses collected high definition photos to track individual sharks by their “freckling” pattern. Using the algorithm, Bear is able to identify the unique patterning on individual sevengill sharks. Eight individuals have been identified and tracked using this method, allowing Bear and other researchers to track the return of these sharks each year. What is crucial for this approach, Bear tells us, “is to have high resolution photographs where the freckling pattern is visible.” While crucial, this technological demand is not a significant barrier for most of the diver-citizen scientists, says Bear, since “most divers these days are using hi def cameras anyway.”
Since the motivation for Bear’s project was to determine baseline populations, knowing more about the number of sharks that are present and returning to the area becomes crucial. Tracking individuals helps to sort out the matter of whether the population of sharks or the population of divers (and therefore reported sightings) is increasing. Securing more data is essential to draw reasonable conclusions about these populations and so the Sevengill Shark Sightings project continues to collect sightings, including those with video and photographic data, submitted by divers in the San Diego area. Specifically, Bear’s project is interested in the population data over a 5- to 10-year period, asking whether the population density appears to stay relatively static or if there are notable changes.
In addition to these research interests, science education is built into this citizen science model. Bear hopes to train local divers in identification techniques for the sevengill shark. The Sevengill Shark Sighting project provides an interesting example of how technology can help citizen scientist organize anecdotal data into important scientific datasets.
Ashley Rose Kelly is a Ph.D. candidate in the Communication, Rhetoric, & Digital Media program at North Carolina State University. Ashley studies how emerging technologies may be changing science communication. She also teaches scientific and technical writing courses as well as an introductory course on science, technology, and society. You can find Ashley on Twitter as: @ashleyrkelly”
(1) Michael Bear is Science Diving Editor for California Diver Magazine and Contributor to Marine Science Today. He lives and works in San Diego, California.
Williams, GD, Andrews, KS, Farrer, DA, Bargmann, GG, and Levin, PS. (2011). Occurrence and biological characteristics of broadnose sevengill sharks (Notorynchus cepedianus) in Pacific Northwest coastal estuaries. Environmental Biology of Fishes 91: 379–388. doi: 10.1007/s10641-011-9797-z.
Williams GD, Andrews KS, Katz SL, Moser ML, Tolimieri N, Farrer DA, Levin PS. (2012).
Scale and pattern of broadnose sevengill shark Notorynchus cepedianus movement in
estuarine embayments. Journal of Fish Biology 80(5): 1380–1400. doi:
Photo: Michael Bear; photo credit Kelli Shaw, 2011.
You might not realize it, but it’s always out there. Planning. Growing. Waiting for the perfect time to strike. You never quite know when it will happen. Maybe July. Maybe August. But you know it’s coming, and you can’t escape it. In an awesome display of speed and power, it bursts from an otherwise calm summer sea and takes over. Terrifying though it is, you just can’t look away.
I’m talking, of course, about the Discovery Channel’s Shark Week, the seven-day marathon of programming celebrating the world’s most feared—and revered—predator. Now, in the midst of it’s 25th year of sidelining would-be beach-goers, Shark Week enjoys ratings (drawing in 3.3 million viewers in its first hour in 2011) previously reserved for major television events and pop culture phenomena like the Super Bowl or American Idol.
Scientists, meanwhile, are hard at work studying these creatures, and they need your help! I know you’re thinking, and don’t worry. We saw Jaws too. But did you know that several of the over 400 species of sharks, including the iconic Great White, are endangered or vulnerable due to commercial fishing and shark finning?
Here’s a few citizen science projects from around the world enlisting the help of divers, fishermen and boaters to contribute data for scientific study or conservation purposes. Happy Shark Week!
Shark Trust invites everyone, especially recreational divers, to report their shark sightings and send in photos for inclusion in their global database used by scientists and conservationists to track and manage sustainable shark populations around the world. Shark Trust ensures the security of its data and safeguards local populations by listing only the region of the sighting, never the exact location, lest it be misused by hunters or fishermen.
According to Michael Bear of California Diver Magazine, divers in the waters off San Diego suddenly began reporting sevengill sightings in 2009. “So little is known about them and their [migration] habits,” said Bear, “[so I wanted to find out why] they began appearing and congregating in a specific spot.” Through his partnership with the Shark Observation Network, the Sevengill Shark Sightings data will contribute to a global database available to researchers and the general public. Bear also founded Citizen Scientists of the Ocean on Facebook, whose relatively modest (but active) membership includes “Her Deepness,” oceanographer and explorer Dr. Sylvia Earle. Like it!
Spot a fin and email it in! The Basking Shark Project from the New England Coastal Wildlife Alliance invites fisherman, whale watchers, and boaters to report their sightings of the basking shark, one of the world’s largest fish at 39 feet long, second in size to only the whale shark. Their triangular dorsal fin often breaches the surface when they feed—a chilling image from an all-but-harmless beast. They’re filter feeders! Your data will help scientists better understand their local population size and distribution patterns.
If you’re lucky enough to spot or swim alongside one of these rare, majestic (and endangered) creatures, snap a photo and send it to ECOCEAN’s Whale Shark Photo-identification Library. Using the same algorithm that NASA astronomers use to analyze star patterns and thus compare photos of the night sky to guide telescopes, scientists can identify and track individual whale sharks by the unique spot patterns on their backs. According to Wired, the approach is not limited to whale sharks, having been adapted for tracking polar bears by their whisker patterns and humpback whales by the shape of their fins, and could revolutionize wildlife tagging and tracking as we know it.
Why Sharks Matter
If you find yourself in Charleston, SC, you can help David Shiffman from Southern Fried Science and the South Carolina Department of Natural Resources capture, tag, and release their resident shark species. At least you’ll be on a boat. Anyone can volunteer, but beware of seasickness!
Da-dum … da-dum …
Don’t look now, but there are researchers hoping you’ll hop in shark-infested waters in the name of science!
Members of ECOCEAN want your help photographing whale sharks on your next ocean outing. Your pictures will be uploaded to the ECOCEAN Whale Shark Photo-identification Library, a photographic database of whale shark (Rhincodon typus) sightings.
Marine biologists will use your photographs to identify whale sharks and keep a record of interactions with individual sharks. Similar to how images of fingerprints can identify specific humans, photographs of whale sharks’ skin patterning, gills, and scars, combined with state-of-the-art pattern-recognition algorithms, allow scientists recognize specific sharks across multiple encounters.
If you’re keen to help out, hop off the boat this summer and submit whale shark photos and sighting information. You will be helping scientists and assisting in the conservation of a threatened species. Not a bad way to spend a summer vacation! Read the rest of this entry »