Florida shark species and the human influence (Final)

This topic submitted by Alex Ress ( ressap@miamioh.edu) at 4:12 PM on 6/8/06.

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Tropical Field Courses -Western Program-Miami University

Alex Ress
GLG 413
June 2006

Florida Shark Species and the Human Influence

The marine environment swelling around the coastal areas of Florida are the ideal habitat for many different species of shark. These dominate species can include blacktips, sandbar, nurse, lemon, and hammerhead sharks. All of these sharks are crucial in the overall ecosystem of the area, creating an important balance from the near top of the food chain. However, as human development grows in these areas this causes many problems for shark populations. Commercial fishing in Florida is ever-growing, thus posing a threat to the survival of these shark species. There is also a greater first hand interaction between human and shark through the means of an attack. As we move closer into their territory, problems are consequently going to arise, giving these majestic creatures a bad name they do not deserve. Through conservation efforts, a greater push to preserve the livelihood of the Florida sharks has begun, helping to increase the population numbers of the sharks. However, as the interaction between shark and human continues to increase, more must be done to allow our two environments to mesh in a safer manner, for both our sakes.
One of the most common sharks of the Florida area is the Blacktip shark or Carcharhinus limbatus. This shark is dark colored with the distinctive marking of a black tip on all the fins except the anal fin growing up to about eight feet. They mostly live in schools and prefer the shallow water containing high mackerel populations. The fishing industry deems the shark very valuable for many of its attributes including its hide, fins, and liver (Boattalk). When attacking humans it employs the hit and run method (Common Sharks of Florida).

Another common shark includes the Sandbar shark, or Carcharchinus plumbeus. This shark is light brown or gray and is identified by its large dorsal fin. In the winter months, the shark migrates south into Florida waters in schools. It is mostly a scavenger and bottom feeder, typically found in deeper waters out from the reef (Common Sharks).

The Nurse shark, or Ginglymostoma cirratum, is very common to Florida waters. Nurse sharks can be identified by the practice of laying on the bottom and the barbels hanging from the nose that allows for better prey detection. It can grow up to thirteen feet and is not very economically sound in the fishing industry for its low value of meat. The shark can be dangerous to humans with its small teeth and strong jaw, but are generally only harmful if provoked (Common Sharks).

Florida is also home to many numbers of the Lemon shark, or Negaprion brevirostris. This shark is a yellow gray color with a typical Whaler tail, as it hails from the Whaler family (Boattalk). It prefers shallow lagoons and often travels into freshwater areas. It can grow up to eleven feet and is not a main portion of the fishing industry (Common Sharks).

Within the coastal waters of Florida lives a few of the nine species of hammerhead within the Sphyrna genus, most common being the Scalloped Hammerhead and the Bonnethead sharks. The distinctive features of the hammerheads include a flattened head extending out in a hammer-like appearance (Common Sharks). Hammerheads swim in large schools and are very competitive for female attention, often participating in many acrobatic maneuvers such as torso thrust and corkscrew to draw intrigue (Klimley 2003).

Sharks play an important role in the Florida reef ecosystem with top-down controls over various other populations. Since most sharks are top predators and even a few are super predators with no natural enemies, they are able to manipulate the food web from the top, either directly or indirectly. Through the hunting of a multitude of species, sharks are able to keep other fish populations in balance, thus maintaining an equal share of predators and prey. They also prefer to hunt the old, weak, and sick which can help to better the health of a prey population, creating a greater chance of strong future generations through healthy reproduction via survival of the fittest. It is the removal of these important controls that will throw off an entire ecosystem through improper distribution of varying populations (Shark Foundation).

The fishing industry is booming throughout the world and is causing huge problems for marine environments. One portion of this industry is shark fishing, which greatly affects the Florida reef systems. Shark fisheries are continually under scrutiny for their apparent overfishing of shark populations in many areas around the world. Management of these fisheries is key in preventing overfishing and exploitation of shark populations. There are four forces pushing the conservation of sharks through the international fisheries; a UN agreement on migratory fish stocks, the Convention of Biological Diversity which incorporates shark conservation into domestic programs, the Bonn Convention which helps to protect listed species, and CITES which aids the protection of threatened species as well through international trade regulation. However, the shark fishery market is plagued with problems. Many issues stems from lack of involvement from many developing countries which make up more than two-thirds of the shark landings, or catches. Their lack of involvement also creates problems in the identification of threatened species, as they have no real numbers on the species or amount of product they are producing with any type of consistency. However, developed countries also are to blame for the overfishing of shark populations. Developed countries lack funding for research and enforcement of the policies set forth for commercial fishing. Thus, the industry can flourish without any real repercussions (Barker and Schluessel, 2005).

The effect of shark overfishing is devastating not only for the shark populations, but also their habitats within Florida’s reef systems. Due to sharks slow growth rates, late maturity, and low fecundity they are very susceptible to overfishing. Their reproduction potential just cannot move as fast as the fishing industry. Many sharks will not mature until late into their teens and then will not even reproduce annually, let alone only producing a few offspring each brood. Without the shark populations to balance out the intricate web of the reef ecosystem, many species are hurting without their great influence. Even the fishing industry is hurting, making the practice uneconomical in relation to the amount of landings decreasing each year (Fish and Wildlife Research Institute).

When entering the coastal waters of Florida, the thought of a shark attack is usually not far from mind. However, it really should be when related to the actual statistics of a shark attack, in fact you should be more worried about a simple drowning or even being struck by lightning. Nevertheless, shark attacks are a problem in coastal areas around the world. Within the United States, Florida by far claims the most attacks than any other state. This is due to the hospitable environments for both sharks and people in the same general area. In 2005, Florida reported 19 attacks of the US total of 39, with one fatality. The greatest number of attacks came from the more highly attended beaches of Florida; Palm Beach, Daytona Beach, ect. The most common species in the Florida area attacking were the blacktip, bull, and the hammerhead, with lower numbers of the lemon and nurse sharks (International Shark Attack File). However, these numbers are relatively small when looking at other fatality causing incidents. The annual average for shark attack fatalities is 25 whereas the bee sting fatality is 1250 and the alligator fatality is 2500. Also in Florida there have been 4 shark fatalities in 30 years, compared to 313 lightning strike fatalities (Fish and Wildlife Research Institute). It is clear that shark attacks are not as common as they are made out to be in the movies and media. Common types of attacks include the hit and run, sneak, and bump and bite attacks. The most common, the hit and run making up 80% of attacks, results in a quick bite and slash without time for a reaction. The sneak and bump and bite attack involve the larger sharks actually circling the person and evaluating its appeal as a potential meal (Caldicott et al.). To prevent an attack one should take precautions to lower the chances of an unlikely attack. One should stay in groups and avoid swimming at night or if bleeding. Avoid wearing bright colors or shiny jewelry and know the common habitat of the sharks, such as sandbars and steep drop offs, and avoid those areas. Taking some caution can prevent a person from being a small percentage in the relatively short list of shark attack victims (Fish and Wildlife Research Institute).

All over the world, shark populations are being hit hard through human interaction via the fishing industry. Many shark species are threatened or endangered and many more are on their way. Hammerhead populations are down 89% and tiger sharks are down 65% in the past 15 years due to overexploitation by the fishing industry, and many of the Florida shark species mentioned above, most relevantly the Blacktip, are headed toward being threatened (Shark Foundation). In order to increase the shark species numbers it is believed than much needs to be done within the management of the international shark markets. As these population numbers decrease, more research is being done to learn more about the sharks that are being marketed. Many researchers work to determine the life histories, reproductive trends, and population dynamics of the sharks to allow for more strict fishing regulations. This would allow for the sharks to safely reproduce and eventually give economical sound size and weights of the sharks being fished. There is also work being done to determine a better way to incorporate the remnants of the leftover sharks into the industrial world, thus creating an economical advantage in using the entire shark (Fong and Anderson 2002).

Sharks play a crucial role in supporting the Florida reef systems through its power at the top of the food chain. As we as humans begin to tread on their territory, we are creating a great imbalance in this ecosystem. We tear down the entire food web through the general elimination of various keystone species. Our fishing techniques and policies are not helping the situation either, with overexploitation and poor management the shark populations are getting hit hard. However, there is hope within conservation efforts to effectively monitor the threatened species and correctly determine the types of sharks deemed fishable. If we wish to keep our close relationship with the oceans and the environment it holds we need to begin to show respect and do our part to maintain its life.


Barker, Michael J., and Vera Schluessel. "Managing global shark fisheries: suggestions for prioritizing management strategies ." Aquatic Conservation: Marine and Freshwater Ecosystems 15.4 (2005): 325-347.

Boattalk. The Boating Information Bureau. June 2006.

Caldicott, David G.E., Ravi Mahajani, and Marie Kuhn. "The anatomy of a shark attack: a case report and review of the literature." Injury 32.6 (2001): 445-453.

Common Sharks of Florida. University of Florida. 29 Mar. 2006 .

Endangered Species Program. U.S. Fish and Wildlife Organization. 29 Mar. 2006 .

Fong, Quentin S.W., and James L. Anderson. "International shark fin markets and shark management: an integrated market preference-cohort analysis of the blacktip shark (Carcharhinus limbatus) ." Ecological Economics January 2002: 117-120.

"International Shark Attack File." Ichthyology at the Florida Museum of Natural History. Florida Museum of Natural History. 25 Mar. 2006 .

Klimley, A. Peter. The Secret Life of Sharks. New York: Simon & Schuster, 2003.

Shark Foundation. Shark Foundation Hai-Stiftung. June 2006.

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