RJD Program Questions
For more information on the field experiences available to graduate students, please visit: the Participation section of this website.
Adopting a shark costs $2500, and funds the purchase of a satellite tag. For the full scoop, please click HERE.
We also have an online store where proceeds from purchasing cool shark apparel goes to supporting our program. Please check it out at: ShopForSharks.com.
Contact Susan Gerrish with any questions about donations at RJD.Donate@gmail.com.
- Use our free high school curriculum
- Take a virtual expedition right from your classroom
- Track our sharks online
- Use RJD scientific data in class research projects
- Invite an RJD shark expert into your classroom for a presentation on a variety of topics
Where? — 117 El Capitan Dr. in Islamorada
When? — 8:30 AM Departure, expected Arrival 3–4PM
Lunch? — Lunch is provided on the boat (cold cuts for sandwiches, fresh fruit, chips and cookies) so you don’t have to worry about that. We just ask that guests please bring a refillable water bottle, as we try to minimize our waste. We also encourage you to bring any snacks or preferred foods. For specific catering options, please contact our Lab Manager Virginia Ansaldi at V.Ansaldi@umiami.edu.
Forms? — Please fill out and bring all forms listed HERE.
Unlike bony fish (also called “teleost” fish) sharks are cartilaginous. Try to bend your arm somewhere it is not jointed, and you will find it impossible without breaking the bone. Try the same with your ear or the tip of your nose and you will see the difference between bone and cartilage. There are some benefits to being cartilaginous: cartilage is both lighter and more flexible than bone. Some sharks are flexible enough to bite their own tails! However, there are also potential downsides—our bones play an important role in protecting our vital organs. Without a bony ribcage, sharks are susceptible to crushing or ramming injuries to their organs—a real danger when you are at risk of being caught in a net or hit by a boat.
Instead of scales like most fish have, sharks are covered with dermal denticles. Dermal denticles literally means “tiny skin teeth”, and in fact each denticle is tooth-like in structure, containing a “pulp” of nerves covered by a crystalline structure of chemical called apatite, which helps make shark skin tough and strong. In the absence of a bony skeleton, this tough skin is critical to protecting sharks from predation and injury; denticles overlap closely that help provide protection from the bite of another shark and from miniscule skin parasites. Denticles make sharks even more hydrodynamic than they would be if they were completely smooth—the way denticles funnel water away from the body can reduce drag by as much as eight percent. Because denticles are much more efficient in displacing water, they also give sharks a stealth advantage. While the water displaced by swimming fish can be heard clearly on a hydrophone, a swimming shark is almost completely silent.
Shark Buoyancy Control
Most fish have what is called a “swim bladder,” a gas-filled organ that helps compensate for their weight and maintain them at neutral or near-neutral buoyancy in the marine environment. Sharks do not. Instead, sharks rely on their exceptionally large and oily liver (remember, oil floats on water) to help remain buoyant. Because the liver in most sharks is so large, most have shorter, more partitioned, intestines than other similarly sized animals, slowing their digestion and leading to more efficient nutrient absorption. Sharks are also helped to remain buoyant by their lighter cartilaginous skeleton and by the hydrodynamic properties of their body shape and fins (like a glider) and their unique dermal denticles discussed above!
Hominids, in contrast, date back no further than 4.5 million years – which means that even counting pre-human hominids, we have been on the plant for only one percent of the time in which sharks have swum in the sea.
The data does not exist to exactly quantify the number of sharks humans remove from the ocean each year. One study, however, estimates that the fins of between 26 and 73 million sharks that are killed per year (some of which are from target fisheries, some of which were finned after being caught as bycatch) are sold in the Hong Kong fin market.
If you do not find what you are looking for, please feel free to ask one of our shark scientists directly: Catherine MacDonald at CMacdonald@inbox.com
- Spread the word
- Learn more about sharks
- Consume sustainable seafood
- Avoid using plastic bags
- Recycle your trash
- Use circle hooks for catch-and-release fishing
- Avoid any products made from sharks
- Don’t eat shark fin soup
- Support reputable shark conservation organizations
- Support RJD’s marine conservation efforts
- Speak to your government representative
- Stay informed – you can keep in touch with us via our social media
Many species of sharks are curious animals. When they come across something unusual, they want to learn more about it. If you or I wanted to know what something was, we’d pick it up and look at it more closely. Because sharks have no hands, they primarily use their mouth to investigate things they are curious about. When they mouth a human out of curiosity, we still perceive it as an “attack”—although in most cases it would be more accurate to describe it as an “accidental” or “experimental” bite. To learn more about why sharks may attack people, please click HERE.
Shark fin soup itself has no color, taste, or smell and requires addition of chicken, beef, or pork broth to add flavor. However, the cartilage from the shark fin provides texture to the soup.
Tens of millions of sharks are killed annually for their fins and are being fished out faster than they can reproduce which is leading to several shark populations declines globally (See FAQ #14 & #15).
In recent years, many people in China and people of Chinese descent around the globe have become increasingly aware of the ecological problems associated with shark fin soup, and have begun arguing that it should no longer be consumed. Recently, the Chinese government announced it will no longer serve shark fin soup at governmental events.
Although shark fins are primarily consumed in Asia, shark finning (and fishing for their fins), is a global phenomenon. According to a recent report, 83 countries or territories supplied more than 10.3 million kilograms (22.7 million pounds) of shark fin products to Hong Kong in 2011. The top countries exporting fins to China include Spain, Mexico, and the U.S. More details can be found by clicking HERE.
Shark finning is the act whereby sharks are caught at sea, their fins are removed and kept, while the rest of the shark’s body at sea. Shark finning occurs mostly because shark meat is rarely consumed. In contrast, trading in shark fins is extremely lucrative. A single bowl of soup can cost hundreds of dollars. In several countries, including the United States, the act of shark finning is illegal, whereby the shark body is not discarded at sea. Instead, the whole body must be brought to shore before the fins are removed and sold.
A study by RJD team members, Dr. Hammerschlag and Austin Gallagher, conducted a global analysis of all shark diving ecotourism and showed that the growing tourism industry can potentially generate more money over time for local economies than directly harvesting sharks for sale (Gallagher & Hammerschlag 2011). This and other similar economic analyses have helped prompt the creation of numerous shark sanctuaries and laws intended to help protect fragile shark populations. Here are a few the recent legal successes for sharks:
- September 2009 — Palau created the first national shark sanctuary. No fishing of sharks is permitted within the national waters of Palau.
- December 2010 — The United States passed the Shark Conservation Act, banning shark finning in US waters. This law means that shark fins cannot be brought to dock in the United States without the bodies of the sharks, dramatically limiting the number of shark fins a vessel can collect on each voyage.
- June 2011 — Honduras created a shark sanctuary protecting sharks along both their Pacific and Caribbean coasts.
- July 2011 — The Bahamas banned all commercial shark fishing within Bahamian national waters.
The RJ Dunlap program uses special fishing units called drumlines (composed of a single weight and attached hook & line) that promotes shark vitality when fishing for sharks. The gear permits species which are ram ventilaters (need to keep moving to breathe) to swim in big circles around the weight when caught. The ability to swim relatively freely also minimizes stress-related C02 and lactic acid buildup in shark muscle. This gear promotes shark survival.
Circle hooks can help reduce negative outcomes for captured sharks over other commonly used hooks, most notably J hooks. Circle hooks are designed to catch in the shark’s jaw, instead of catching on the shark’s stomach or gills, which can otherwise cause serious injury. The hooks can also easily be removed from the jaw and leave a very superficial wound that heals very quickly. Circle hooks also help us selectively target sharks, reducing unwanted bycatch of other species. We recommend circle hooks not only for research-related capture, but for recreational fishermen practicing catch and release fishing who want to increase the likelihood of release their catches in good condition.
When a caught shark is brought onto a specialized, partly-submerged, platform on the back of our research vessel, a saltwater pump is immediately placed in the sharks’ mouth. This allows highly oxygenated water to flow over its gills throughout the shark’s brief ”check-up.” During this workup, sharks have a small muscle biopsy taken (recaptured sharks demonstrate that the biopsy site is completely healed within just a few weeks), are tagged with a spaghetti tag in their dorsal fin (where they have no nerve endings and no blood vessels), have blood drawn, are measured, have a small clip of their fin cartilage taken, and are released.
The traditional method for getting the type of data we collect was to kill the animals. Although capture may still be a relatively stressful process for sharks, our work focuses on minimizing shark stress to the greatest extent possible and promoting shark vitality and survival.
Our work has been proved successful with minimal shark stress. Our methods have been approved by the University Animal Welfare & Care Committee. It is also worth noting, that based on all available scientific evidence available, it appears that sharks do not feel pain.