The Biggest Bull Shark…Ever?

Every once in a while, the ocean presents us with something truly amazing – whether it’s a crazy storm or a record catch, these events serve to remind us of the awesome power and beauty of the sea.

It was early June, and we were conducting another day of our continual catch and release shark surveys in the Florida Keys. In general, April, May and June tend to be some of the heaviest months for large sharks in the Keys, a time when these coasts are visited by the “semi-pelagics” that are following the fishes that spawn offshore. As our team hauled in the final drumline (shark-friendly, passive fishing device) of the day, something big tugged on the other end, almost pulling our team into the water.

“It looks bull-y,” remarked Dr. Neil Hammerschlag.

“I see the football-y shape,” I responded, looking 70 feet down on the shadow coming towards me.

Turns out we were right, it was indeed a bull shark – Carcharhinus leucas – a large female. As we brought her closer to the boat, it soon became evident that this wasn’t just any bull—she was over 8 feet long, and was thicker than any shark I have seen in the Caribbean (including 14 foot tigers and 12 foot hammerheads).

Bull sharks are a fascinating species, and our tagging experiments tell us that they are constantly on the move, timing their movements with prey such as tarpon and ladyfish in the Everglades, while also alternating to deeper oceanic locations for mating and birthing. Of the 80 or so bull sharks we have tagged and released in the last several years (one of the more rare species we encounter), most are around 6-6.5 feet, a size representing a mature adult. This bull shark dwarfed every other bull I have seen, and there is no doubt in my mind this bull is part of a very elite club in Florida-and probably Western Atlantic. After measuring her length and sampling her blood for reproductive hormones and stress parameters, she was released in great condition, swimming away to reclaim her seat on the throne of apex marine predators.

Members of the R.J. Dunlap Marine Conservation Program with the Bull Shark.

Reports of the tagging of the massive bull made national news in a few days, with stories commenting that the animal could have weighed up to 1,000 pounds. While we didn’t have a scale on board, this fish was every bit of 800-850 pounds. There is a chance she could have been close to 1,000 pounds, perhaps making it the largest bull ever caught. And while we will never know her true weight, it would be a slap in nature’s face to ever sacrifice an animal this size for a record book. When the news reports spread of this amazing catch and tag, I was excited – knowing it would be seen by many fishermen worldwide, hopefully serving as an example of not needing to sacrifice large animals to still get an amazing experience. And it is great that many anglers are subscribing to this conservation ethic. Pictures last forever, and so will my memory putting my arms around her belly and feeling truly humbled and impressed.

Austin Gallagher is a PhD student at the Abess Center for Ecosystem Science and Policy at the University of Miami. He is also a research assistant for the RJ Dunlap Marine Conservation program, focusing his doctoral studies on shark conservation biology.

-Austin Gallagher
PhD Student, Research Assistant
RJ Dunlap Marine Conservation Program
Abess Center for Ecosystem Science and Policy
www.rjd.miami.edu
www.austingallagher.com

(Video) RJD featured on “The Next Web”

The Next Web (TNW) is known around the blogosphere as one of the top online communities for internet tech, business and culture, with over 5 million monthly visits. The R.J. Dunlap Marine Conservation Program was recently featured in an article covering Summit Series, and the 2011 “Summit at Sea” event, that has now raised nearly $1 million to protect the world’s oceans. To read the article click here.

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(Video) Does Ecotourism in the Bahamas affect Tiger Shark Movement and Behavior?

Director of the R.J. Dunlap Marine Conservation Program, Dr. Neil Hammerschlag, discusses the relationships between Ecotourism and Tiger Shark behavior in the Bahamas. Weigh in on the conversation by leaving a comment below.

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(Video) Study Shows Link Between Neurotoxins in Shark Fins and Brain Diseases

Sharks are among the most threatened of marine species worldwide due to unsustainable overfishing. They are primarily killed for their fins alone, to fuel the growing demand for shark fin soup, which is an Asia delicacy. A new study by University of Miami (UM) scientists in the journal Marine Drugs has discovered high concentrations of BMAA in shark fins, a neurotoxin linked to neurodegenerative diseases in humans including Alzheimer’s and Lou Gehrig Disease (ALS). The study suggests that consumption of shark fin soup and cartilage pills may pose a significant health risk for degenerative brain diseases.

“Shark fins are primarily derived through finning, a practice where by shark fins are removed at sea and the rest of the mutilated animal is thrown back in the water to die,” said co-author Dr. Neil Hammerschlag, research assistant professor of Marine Affairs & Policy and director of the RJ Dunlap Marine Conservation Program (RJD) at UM. “Estimates suggest that fins from as many as 70 million sharks end up in soup.  As a result, many shark species are on the road to extinction. Because sharks play important roles in maintaining balance in the oceans, not only is shark fin soup injurious to the marine environment, but our study suggests that it is likely harmful to the people who are consuming them.”

Seven species of shark were tested for this study: blacknose, blacktip, bonnethead, bull, great hammerhead, lemon, and nurse sharks. Samples were collected from live animals in waters throughout South Florida. “The concentrations of BMAA in the samples are a cause for concern, not only in shark fin soup, but also in dietary supplements and other forms ingested by humans,” says study co-author Prof. Deborah Mash, Director of the University of Miami Brain Endowment Bank. The Bank supports basic and clinical research and holds one of the world’s largest collection of postmortem human brains encompassing a wide range of neurological disorders.

The new study found levels of between 144 and 1836 ng/mg of BMAA, which overlapped the levels measured in the brains of Alzheimer’s and ALS victims. “Not only does this work provide important information on one probable route of human exposure to BMAA, it may lead to a lowering of the demand for shark fin soup and consumption of shark products, which will aid ocean conservation efforts,” added Hammerschlag.

The project was funded through a donation from the Herbert W. Hoover Foundation. Click here to read the full story.

Will this effect the demand for shark fin soup and other shark fin products worldwide? Comment below with your thoughts.

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Video: Shark Research with RJD on Mysteriously Beached Lemon Shark

Last year, after a lemon shark was reported dead on a Florida beach, Director of the R.J. Dunlap Marine Conservation Program Dr. Neil Hammerschlag, and two Ph.D. students, Austin Gallagher and David Shiffman, conducted a necropsy on the shark.

This very short video teaches you basic anatomy and gives you a peak into the life of a lemon shark.

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Webinar of the Week: Eutrophication and the Subsequent Waste-Water Management Scheme in Boston Harbor

In this week’s webinar, Rosenstiel School student Abbey Cherish Pennington talks waste-water management in the Boston Harbor during Dr. Neil Hammerschlag’s Marine Conservation class.

The Boston Harbor Project was one of the biggest wastewater management projects in the US, conducted from 1991 to 2000. The relocation of the sewerage outfall pipe from the mouth of Boston Harbor, to 15km offshore in Massachusetts Bay ended over a century of direct wastewater discharges into the harbor. The project led to a reduction in: total nitrogen, total phosphorus, total suspended solids and particulate organic matter by approximately 80-90%. Macroalgae, phytoplankton and submerged aquatic vegetation need a certain level of nitrogen and phosphorus, as they are essential elements for their growth.

This study provides an opportunity to examine ecosystem responses to major reductions in pollutant input, which could be used as an example for other waste-water management schemes, for example in Biscayne Bay, Florida.

-Andrew DeChellis
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