By nature, sharks are difficult to study and good fisheries data are hard to obtain. The practice of finning, which is mostly an unreported practice is robbing scientists of population and capture data. Many pelagic shark species are widespread and do not school. Many larger sharks travel vast distances alone. Most large sharks have late onset of fertility decades give birth to few young and have long gestation periods, making them very vulnerable to overfishing.
Therefore, it is very difficult to arrive at a sustainable number. This is why most commercial shark fisheries collapse economically. Until that is achieved and it can be enforced, then the source of fins must stop and fins made illegal. Only the sawfishes Sawfishes Pristidae spp. Oceanic whitetip shark Carcharhinus longimanus Porbeagle shark Lamna nasus Scalloped hammerhead shark Sphyrna lewini Smooth hammerhead shark Sphyrna zygaena Great hammerhead shark Sphyrna mokarran Manta rays Manta spp.
In Silky shark Carcharhinus falciformis, Thresher sharks Alopias spp. Great white sharks are protected under California and Federal Law from fishing commercially or recreationally. Even,fins from these protected sharks have been identified in the shark fin trade through DNA analysis. These laws regulate the trade and transport of listed species across country lines by countries that recognize the treaty.
Nearly twice as many nations had teams in the World Cup. In investigators performed DNA testing on wholesale shark fin distributors, discovering the fins of the few protected species in Hong Kong, Singapore and here in the US. In Shark Stewards, working with at the California Academy of Sciences sequenced 17 species of sharks from shark fins bought in San Francisco Chinatown, including threatened species like thresher sharks, and endangered hammerhead sharks.
Once the fin is dried and treated, the species is nearly unidentifiable. The protections in place are not strong enough, or broad enough to protect sharks. Shark fins are used to make shark fin soup, a delicacy once prepared exclusively for the Chinese emperors and nobility.
The cartilage from the fin is carefully dried and prepared, and used as an ingredient in a soup flavored with seafood or chicken broth and herbs.
The serving of the dish is considered very prestigious and even propitious. Dried shark fin is the most expensive seafood product by weight, and is creating huge incentive for fishermen to hunt sharks, solely for their fins. Although Chinese and people of Chinese descent primarily consume the dish, the consumption is increasing in western societies with affluent consumers, Asian and non-Asian.
However, shark fin is still a major trade and is consumed widely in the USA, putting shark populations at risk. This is an attack on an unsustainable fishing practice and trade.
The cultural associations are modern, associated with prestige. The problem is simple economics: increasing affluence creates increased demand. It is situated between the pelvic fins and the tail on the bottom of the body the ventral side.
These are also used for stability. Caudal Fins are also known as the tails of sharks. The animal swishes this fin from side to side in order to propel its entire body forwards. The nature of this fin does not allow for backwards movement. Therefore, if a shark needs to move away from an object, it is forced to either drift backwards or to turn away from it and continue in a forwards direction.
A shark is required to move swiftly and without being detected to allow it to hunt prey effectively. The fins are vital for their quick, agile movements and their impressive speed.
Their design reflects ingenuity and insight. Due to this particular function, the liver is considered to be a hydrostatic organ. The shark anatomy includes an intestine that is used for digestion. When a shark needs to get rid of waste, it utilizes its kidneys, genitals, and cloaca. The cloaca is an opening that the kidneys and genitals empty into. The skeleton of a shark is entirely composed up of cartilage. It is a bit alarming, but sharks do not have bones. The fact that sharks have cartilage instead of bone is extremely beneficial.
Cartilage is lighter than bone; this helps the shark stay afloat. Because cartilage is also extensively durable and flexible, sharks have the ability to have tight radius turns.
The skull of a shark, which is also comprised of cartilage, can vary in shape. The mouth of a shark, one of its most recognizable features, is usually located on the ventral side. Sharks are constantly replacing their teeth; believe it or not, some sharks use more than 30, teeth over a life span.
When a new tooth grows, the skin maneuvers the tooth into a proper position. Although an extensive amount of information has not been found about sharks, we do know that they have taste buds. Some sharks spit things out after they have bit into them; this is most likely due to the fact that they did not like the particular taste.
Sharks have the reputation of devouring almost anything and anyone, but they are certainly pickier than many people realize. Without a doubt, sharks use more than their eyes and ears to track down prey. The lateral line is another sensory system that works simultaneously with the ampullae of Lorenzini. The lateral line is similar to ears because it detects low-frequency vibrations.
Vibrations from a distance can be detected easily by the lateral line, and the direction of water flow can also be determined by the lateral line. Because sharks use the sense sound to find their food, ears are needed in addition to the ampullae of Lorenzini and the lateral line.
Sharks have an inner ear that is used to pick up acceleration and gravity in addition to sound. Sharks have exceptional eyes that enable them to see acutely, even in low light. Behind their retina, is the tapetum lucidum; this is a layer that is comprised of silver guanine crystals that reflects light as it exits the eye.
This is the part of the shark anatomy that enables sharks to have the ability to see in low light. The eyelids of some sharks are certainly not typical. There are sharks that have what is called a nictating membrane. This feature provides a substantial amount of protection for the eye.
When sharks get relatively close to a particular object, or when they are feeding, the nictating membrane closes, thus acting as a shield for the eye. Some sharks, like the great white shark , actually have a set of muscles that roll the eye into its socket whenever the eye needs protection. The eyesight of bony fish pales in comparison to the sight of a shark.
The shark anatomy allows them to see in dim light, they can detect the contrasts of light and shadow, and their pupils can dilate and contract.
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