Threats To Shark Populations
Shark Nets
Shark meshing programs have a significant environmental cost, in terms of non-target bycatch such as other marine animals (turtles, fishes, dugongs, etc) and non-target shark species that are killed in the nets, including protected and endangered species.
Many sharks drown every year after becoming entangled in nets intended for other species.
This is why shark meshing has been listed as a Key Threatening Process by the N.S.W. Fisheries Scientific Committee.
Shark meshing programs have a significant environmental cost, in terms of non-target bycatch such as other marine animals (turtles, fishes, dugongs, etc) and non-target shark species that are killed in the nets, including protected and endangered species.
Many sharks drown every year after becoming entangled in nets intended for other species.
This is why shark meshing has been listed as a Key Threatening Process by the N.S.W. Fisheries Scientific Committee.
Over Fishing
One of the most serious issues facing shark populations today.
Shark populations take a long time to recover from overfishing. They grow very slowly and take a long time to reach sexual maturity – 20 years or more in some species. When they do reproduce, they produce very few offspring compared to other food fish species. These factors have already endangered several species of shark, particularly in coastal areas.
Declining shark numbers can have serious consequences for ocean ecosystems. Sharks are a vital part of the food chain, their predatory nature helps to keep populations of their prey species in check. Without sharks to help maintain a healthy
balance, marine environments are at great risk of permanent damage.
One of the most serious issues facing shark populations today.
Shark populations take a long time to recover from overfishing. They grow very slowly and take a long time to reach sexual maturity – 20 years or more in some species. When they do reproduce, they produce very few offspring compared to other food fish species. These factors have already endangered several species of shark, particularly in coastal areas.
Declining shark numbers can have serious consequences for ocean ecosystems. Sharks are a vital part of the food chain, their predatory nature helps to keep populations of their prey species in check. Without sharks to help maintain a healthy
balance, marine environments are at great risk of permanent damage.
By-Catch
Millions of sharks die every year after being caught by means intended to catch other fish, especially on longlines intended for tuna and swordfish.
In the Mediterranean sea alone, as many as 100,000 sharks die as a result of by-catch every year. While by-catch of other species such as dolphins has declined after highly publicised campaigns to protect them, the undeserved bad reputation of sharks is slowing down efforts to protect them from this wasteful and destructive practice.
Millions of sharks die every year after being caught by means intended to catch other fish, especially on longlines intended for tuna and swordfish.
In the Mediterranean sea alone, as many as 100,000 sharks die as a result of by-catch every year. While by-catch of other species such as dolphins has declined after highly publicised campaigns to protect them, the undeserved bad reputation of sharks is slowing down efforts to protect them from this wasteful and destructive practice.
Shark Products
A huge industry is developing around the use of shark products for improving human health, despite the lack of good scientific evidence to support it. Oil extracted from the livers of sharks is becoming increasingly popular as a booster for the immune system and even as a way of preventing cancer, thanks to an erroneous belief that sharks don’t suffer from cancerous tumors. Shark cartilage is harvested for the same reason.
Shark products are often sold in tourist shops despite the fact that in many countries it is illegal to catch the animals from which they come. The teeth and jaws of the great white shark can fetch substantial sums on the international market, with single teeth often selling for over $100 and a whole set of jaws from a big shark fetching up
to $10,000 in the USA. Illegal smuggling of teeth and jaws from white sharks is
becoming increasingly common in countries such as South Africa, where the sharks
are protected by law.
A huge industry is developing around the use of shark products for improving human health, despite the lack of good scientific evidence to support it. Oil extracted from the livers of sharks is becoming increasingly popular as a booster for the immune system and even as a way of preventing cancer, thanks to an erroneous belief that sharks don’t suffer from cancerous tumors. Shark cartilage is harvested for the same reason.
Shark products are often sold in tourist shops despite the fact that in many countries it is illegal to catch the animals from which they come. The teeth and jaws of the great white shark can fetch substantial sums on the international market, with single teeth often selling for over $100 and a whole set of jaws from a big shark fetching up
to $10,000 in the USA. Illegal smuggling of teeth and jaws from white sharks is
becoming increasingly common in countries such as South Africa, where the sharks
are protected by law.
Shark Finning
Finning is a destructive and wasteful practice which involves catching a shark, cutting off its fins and discarding the rest of the animal, which is often thrown back into the water to die.
No one knows for sure how many sharks die in this way every year, but it is thought that the number of sharks traded globally every year is between 26 - 73 million (Clarke et al 2006). This has the potential to cause immense damage to shark populations worldwide. For example the Shortfin Mako, whose conservation status has changed from from ‘Near Threatened’ in 2000, to ‘Vulnerable’ today.
Shark fins are considered a delicacy in some parts of the world, notably East Asia. Some
countries, such as USA, have banned shark finning in the last few years but finning is still
practiced all over the world in places as far apart as South American and Australia and
many species are declining as a result.
Finning is a destructive and wasteful practice which involves catching a shark, cutting off its fins and discarding the rest of the animal, which is often thrown back into the water to die.
No one knows for sure how many sharks die in this way every year, but it is thought that the number of sharks traded globally every year is between 26 - 73 million (Clarke et al 2006). This has the potential to cause immense damage to shark populations worldwide. For example the Shortfin Mako, whose conservation status has changed from from ‘Near Threatened’ in 2000, to ‘Vulnerable’ today.
Shark fins are considered a delicacy in some parts of the world, notably East Asia. Some
countries, such as USA, have banned shark finning in the last few years but finning is still
practiced all over the world in places as far apart as South American and Australia and
many species are declining as a result.
Long Line Fishing
Longlines are the most significant factor in the rapid diminishment of shark populations in the oceans. Longlines ranging in length from one mile to over one hundred miles are baited with fish (often illegally killed dolphins or seals), and are meant to target shark, swordfish, and tuna. The sharks targeted are caught mostly for their fins (which account for only 4% of their body weight) and also for their cartilage, liver oil and teeth.
The longline fishermen remove the fins and toss the live shark back into the sea to die an agonizing death. Unable to swim, they slowly sink towards the bottom where other fish eat them alive. If longlines are not abolished, the oceans will lose most species of sharks within the next decade.
Longlines are the most significant factor in the rapid diminishment of shark populations in the oceans. Longlines ranging in length from one mile to over one hundred miles are baited with fish (often illegally killed dolphins or seals), and are meant to target shark, swordfish, and tuna. The sharks targeted are caught mostly for their fins (which account for only 4% of their body weight) and also for their cartilage, liver oil and teeth.
The longline fishermen remove the fins and toss the live shark back into the sea to die an agonizing death. Unable to swim, they slowly sink towards the bottom where other fish eat them alive. If longlines are not abolished, the oceans will lose most species of sharks within the next decade.
References:
Shelley C. Clarke, Murdoch K. McAllister, E. J. Milner-Gulland, G. P. Kirkwood, Catherine G. J. Michielsens, David J. Agnew, Ellen K. Pikitch, Hideki Nakano and Mahmood S. Shivji, “Global estimates of shark catches using trade records from commercial markets” Ecology Letters (2006) 9: 1115–1126
Updated 2014
Shelley C. Clarke, Murdoch K. McAllister, E. J. Milner-Gulland, G. P. Kirkwood, Catherine G. J. Michielsens, David J. Agnew, Ellen K. Pikitch, Hideki Nakano and Mahmood S. Shivji, “Global estimates of shark catches using trade records from commercial markets” Ecology Letters (2006) 9: 1115–1126
Updated 2014