Are sharks predators or prey?

Conclusion

The grey nurse sharks critically endangered status on off the eastern coast of Australia will remain an issue until the adequate research and monitoring of its mating and migratory characteristics is done (Department of Environment 2014). The management strategies that are in place for the time being are appropriate, although the current numbers of c. Taurus in the east coast of 1000-1600 are still alarming and not supporting the effectiveness of the current management strategies.

What can be done?

- explore alternate methods of shark control activities and encourage further monitoring of the nets
- ensure all fishing is controlled and that commercial fisheries record the number of grey nurse sharks they catch using a compulsory log book implemented by the Recovery Plan for the Grey Nurse Shark (2014)
- The grey nurse sharks status of critically endangered means that it is not to be caught recreationally/commercially, further monitoring should be implemented to ensure this is the case
- More research is needed in order to understand the specie

Recovery Plan for the Grey Nurse Shark (Carcharias taurus) - following this plan is said to be useful in helping the population on the road to recovery

//www.environment.gov.au/system/files/resources/91e141d0-47aa-48c5-8a0f-992b9df960fe/files/recovery-plan-grey-nurse-shark-carcharias-taurus.pdf

What is causing the decline?

Shark control activities (meshing, netting, culling)

(Google Images 2014)

Shark control activities such as Culling and meshing are practices that are also contributing to the decrease in shark populations. Culling targets sharks that come a certain distance to the shore line and seem to be a threat to local beach goers (Reed, Le Page 2014).

Finning

Finning is said to be the most responsible cause to the decline in shark populations (Cemare et al 2007). It is the brutal act of removing the fins from the shark; in most cases the remainder (carcass) of the shark is thrown back into the water where it’ll sink to the bottom of the ocean and die (Speigal 2001). The finning usually occurs whilst the shark is still alive making the process that bit more tortuous for the animal.

Recreational/Commercial Fishing

Due to pressures from the Australian commercial and recreational fishing industries, threats from finning, activities such as ‘shark control’ measures, and ecotourism the grey nurse shark has remained listed as vulnerable since (Department of Environment 2014).

Grey Nurse Shark injured by a hood (Google Images 2014)

Around 6% of grey nurse sharks have been recognised to have signs that they have encountered fishing gear at some point in their life (Department of Environment 2002).

Population Numbers/Research

New South Wales Government noticed that the population was declining and under the Fisheries Management Act of 1994 pronounced them as critically endangered in the year 2000 (Department of Environment 2014). On the east coast the grey nurse shark population is estimated to be anywhere between 1146-1662.

What the Grey Nurse Shark is labelled as by different states and organisations. Labels include endangered, critically endangered, protected and threatened (Department of Environment 2014)

The NSW Department of Primary Industry looked into the population of grey nurse sharks along the east coast. In the 1950's & 1960's the species was present in 60 different sights along the east coast, the DPI revisited these sites as found that in 63% of them there was no sighting of the shark.

The Grey Nurse Shark

Distribution of the Grey nurse shark Population along the east coast of Australia.
(Department of the Environment 2015)

The Grey Nurse shark (Charcharias Taurus) is found on the east/west coast of Australia. As most sharks the grey nurse has certain life characteristics that hinder its ability to procreate as quickly as it is being harvested(Department of Environment 2015).

Characteristics which make sharks unable to recover as fast as they are being harvested(Tomic 2014)

The issue?

Sharks world wide are being highly portrayed as a vicious

predator that is lurking in the oceans, waiting for its chance

to attack innocent civilians. For this reason people do not

pay much attention to the many issues surrounding

this species that are in fact threatening their populations.

Increasingly they are harvested for their fins and meat

whilst also being culled due to the belief that they pose

a threat to society.

Throughout the world sharks are being harvested for

a number of reasons, these including for their fins and culling

due to the belief that it will reduce the number of ‘attacks’ on humans.

Small snippet from the 1975 Steven Speilberg film 'Jaws' - This film as well as many others instilled fear of sharks in many people world wide.

Sharks Are Important
Why?

Sharks are an apex predator (keystone species) which means that they are at the top of the marine food chain, controlling the populations of their prey. Scientist have said on a number of accounts that without sharks the marine food chain would collapse completely.

e.g. in the mid atlantic the shark population was destroyed, this saw their prey, the clown nose string ray population to grown excessively, ending it the complete depletion of scallops in that region.