Grey Nurse Shark Essay

Introduction
The grey nurse shark belongs to the Odontaspididae family and inhabits the marine ecosystem. The grey nurse shark is a keystone species, meaning it’s a species which plays a crucial role in the way an ecosystem functions, without a keystone species, an ecosystem would be dramatically different (National Geographic. 2016). As the Grey Nurse Shark is an endangered keystone species applications and limitations are required through scientific knowledge and understanding to develop solutions to enhance the total population of the species. As a human endeavour an attempt to get this species to breed more efficiently so it can create more offspring and help prevent the endangerment of this species the introduction of organised breed

may be introduced.
Biological Relevance
The Grey Nurse Shark belongs to the marine ecosystem and plays an important role in maintaining a balance as it controls prey as it is a top-order predator (Jantos. 2014). By consuming a variety of different species such as coral, fish, shrimp, squid, and shellfish it allows plankton, phytoplankton and smaller fish to thrive. Without the grey nurse shark a part off the ecosystem, their prey would then overpopulate causing them to consume all the resources and make them extinct. (Baig. 2012)
Humans have impacted the grey nurse shark substantially and have contributed to the low numbers of grey nurse sharks alive today.

The Grey Nurse Shark was the first ever shark in the world to be protected; conducted by the New South Wales government the species is seen as protected in 1984, but within a quick 16 years from 1984 to 2000 the classification went from “protected species” to “Critically Endangered” (Australian Government. 2015). The cause of this protection include the hunting of the shark, global warning and attempted relocation of the animal. The grey nurse shark’s population is extremely low as there are thought to be only 1000 left off the east coast of Australia, no doubt that humans have played a role in this. During the 19th century hunting this shark was legal as their liver oil was used to fuel lamps and lanterns. The grey nurse shark isn’t typically aggressive and because of this it then became a prime target for spear fishing competitions, which occurred during the 1950s to 70s which nearly caused the extinction of the shark (Queensland Government, 2012). The Grey Nurse Shark was also hunted for its unique skin as it makes high quality leather, the shark has also been caught for recreational fishing and eating. Humans have also effected the shark’s population drop through the employment of shark nets which are deemed to protect humans but are really hurting animals. In the relocation process, most sharks either die from stress or starvation before they

are released (Jantos. 2014). Through global warming it has caused warmer weather, which has an effect of the temperature of the first layer of the ocean. Because of the temperature rise of the water some producers are unable to grow which has an effect of the top order predators. These top order predators rely on producers and first order consumers to survive and without some producers it has effect of what higher order consumers eat. Human have played a major role in the almost extinction of the Grey Nurse Shark from hunting in the 1900s, the implications of shark nets and global warming.

Effects of the issue
Human activities have had a negative effect on the Grey Nurse Shark for their economic, social and cultural benefits. Activities such as hunting the Grey Nurse Shark would have both an economical and cultural benefit on humans as killing sharks for its skin was profitable and hunting them was seen as a sport. Similarly, global warming has caused water temperatures to rise changing what producers grow in the ocean changing what first trophic level animals eat, having a chain reaction effecting top trophic predators such as the Grey Nurse Shark (Australian Government.2015). Global warming was an economical decision made by humans to burn greenhouse gases to produce resources which now have had an effect on an ecosystem. In attempt to protect humans from sharks, relocation was a method of protection for social reasons. In the attempted relocation these shark rarely survive. All these examples have benefited the human but not the Grey Nurse Shark. For these reasons humans may have benefited but it also has a social and ethical effecst. The Grey Nurse Shark is Important to its ecosystem as it maintains the hierarchy of the different species living in the ecosystem by consuming 2nd and 3rd order consumers, and allows the 1st order consumer to thrive and maintain the ecosystem. Ethically if the species is extinct it will play on human’s morals knowing that they contributed to the cause of a species not existing anymore. Furthermore, it will have a social effect on future generations of people in not knowing what this certain species did and how it contributed to its ecosystem.
The main reason behind the Grey Nurse Shark endangerment is not just the human input through hunting but it is the unique breeding periods of the species.

The Grey Nurse Shark has the slowest breeding rate compared to any other shark as it only breeds once every two years. Mating only occurs during autumn and the young are born in the winter during a 9-12-month gestation period. As only two sharks can be produced in one litter one in each uterus it causes the more fully developed embryos to eat the less developed embryos (Australian Government. 2015). Because of this unusual breeding style, the Grey Nurse has nearly reached extinction, but using scientific knowledge it can be applied to enhance the chance of breeding. Much like the situation the two Panda Bear’s in the Adelaide Zoo are set up, Grey Nurse Sharks should be as well, introduced during Autumn in the hope that they will produce offspring by

Winter.
Management policies
In order to reduce the impact of humans on the endangerment of the Grey Nurse Sharks there are now protected zones such as critical habitats, or sanctuary zones, within marine parks to provide the best chance of survival for the species (Gilligan, 2015). In 2003, introduced by the Australian government were fishing and diving laws to protect the sharks and its habitat. Negatively to this enforcement of law has an effect of the number of tourists visiting this area effecting in an economical way. Satellite tags have been in use along the east coast of Australia to track and gain knowledge about the grey nurse shark (Save Our Sharks, 2008). From these tags, information retrieved include water depth and temperature, movement patterns and time spent at sites allowing protection on the species to be more accurate by knowing where they are most likely to live.
Conclusion
To conclude the Grey Nurse Shark is an endangered keystone species effected by human, environmental and behavioural issue. The application and limitation understanding is addressed through the scientific knowledge of introducing two species during breeding times will enhance the chance of creating offspring. It has been trialled at the Adelaide Zoo with two Chinese Pandas but has not had the expected result.