Current Threats to Marine Current Threats to Marine MammalsMammals

By Tim ChinBy Tim Chin

Current ThreatsCurrent Threats

◊ PollutionPollution

◊ OverfishingOverfishing

◊ EntanglementEntanglement

◊ OtherOther

PollutionPollution

◊ NoiseNoise

◊ OilOil

◊ ChemicalChemical

◊ Plastics and DebrisPlastics and Debris

◊ The Plastic SeaThe Plastic Sea

Noise PollutionNoise Pollution

◊ Many cetaceans, such as Many cetaceans, such as certain whales and dolphins, certain whales and dolphins, rely on sound for rely on sound for communication and locating communication and locating food. They are adversely food. They are adversely affected by human-made affected by human-made noise.noise.

◊ Noise pollution can come from Noise pollution can come from a wide variety of sources, with a wide variety of sources, with some of those being ship some of those being ship traffic, seabed drilling, seismic traffic, seabed drilling, seismic surveys, sonars, surveys, sonars, oceanographical experiments, oceanographical experiments, recreational activities, and recreational activities, and underwater explosions.underwater explosions.

Noise PollutionNoise Pollution

◊ Low levels of noise pollution are Low levels of noise pollution are enough to cause a change of enough to cause a change of behavior in whales and dolphins. behavior in whales and dolphins. They will generally try to escape They will generally try to escape from the source of the noise, which from the source of the noise, which can result in them being forced out can result in them being forced out of their habitat.of their habitat.

◊ Higher levels of noise pollution, Higher levels of noise pollution, such as the sound of underwater such as the sound of underwater explosions, can cause great explosions, can cause great discomfort and stress. It can even discomfort and stress. It can even result in physical acoustic trauma result in physical acoustic trauma in the form of tissue damage to the in the form of tissue damage to the ears.ears.

◊ Cetaceans affected by high Cetaceans affected by high intensity noise pollution, with intensity noise pollution, with sonars being an example, are likely sonars being an example, are likely to become stranded and die.to become stranded and die.

Oil PollutionOil Pollution

◊ Oil is another type of pollution Oil is another type of pollution that negatively impacts that negatively impacts marine mammals. It is marine mammals. It is generally introduced into the generally introduced into the environment through environment through accidental spills.accidental spills.

◊ Oil is a compound that can Oil is a compound that can destroy the insulating destroy the insulating properties of a marine properties of a marine mammal’s skin.mammal’s skin.

Oil PollutionOil Pollution

◊ It is often the case that oil is It is often the case that oil is unintentionally eaten during unintentionally eaten during removal attempts. If ingested, removal attempts. If ingested, the toxic oil can damage a the toxic oil can damage a marine mammal’s organs, marine mammal’s organs, which could result in death.which could result in death.

◊ If inhaled, which is usually If inhaled, which is usually done by whales and dolphins done by whales and dolphins coming up for air, the oil can coming up for air, the oil can cause pneumonia.cause pneumonia.

◊ Many times it is overlooked, Many times it is overlooked, but oil pollution can destroy but oil pollution can destroy the habitats of marine the habitats of marine mammals, forcing them to mammals, forcing them to travel elsewhere or perish.travel elsewhere or perish.

Chemical PollutionChemical Pollution

◊ Chemical pollution is a type Chemical pollution is a type that can contaminate the whole that can contaminate the whole of a marine food web. of a marine food web.

◊ In a contaminated environment, In a contaminated environment, as smaller fish eat plankton, as smaller fish eat plankton, and the larger fish eat the and the larger fish eat the smaller fish, the toxins that smaller fish, the toxins that exist will greatly accumulate in exist will greatly accumulate in the bodies of large fish. the bodies of large fish.

◊ Since marine mammals are at Since marine mammals are at the top of their food chain, the the top of their food chain, the high levels of chemical high levels of chemical pollutants in their food will build pollutants in their food will build up in their bodies, in areas such up in their bodies, in areas such as fatty tissue and breast milk.as fatty tissue and breast milk.

Chemical PollutionChemical Pollution◊ Marine mammals suffer from the Marine mammals suffer from the

increasing concentrations of heavy increasing concentrations of heavy metals, PCBs, dioxins, DDT, and other metals, PCBs, dioxins, DDT, and other persistent organic pollutants that are persistent organic pollutants that are dumped or leaked into the ocean.dumped or leaked into the ocean.

◊ Due to the bioaccumulation of Due to the bioaccumulation of chemical pollutants, marine mammals chemical pollutants, marine mammals can suffer from a wide array of can suffer from a wide array of illnesses and disruptions to their illnesses and disruptions to their normal body functions. Pesticides and normal body functions. Pesticides and industrial compounds usually have a industrial compounds usually have a negative impact on the endocrine, negative impact on the endocrine, digestive, and nervous systems, digestive, and nervous systems, which can lead to a decrease in which can lead to a decrease in health, growth and development health, growth and development issues, a weakened immune system, issues, a weakened immune system, and diminished reproductive abilities. and diminished reproductive abilities.

◊ Chemical pollutants can also cause Chemical pollutants can also cause cancer.cancer.

Plastics and DebrisPlastics and Debris

◊ Plastic and other debris in the Plastic and other debris in the ocean are a large threat to ocean are a large threat to the wellbeing of marine the wellbeing of marine mammals, especially due to mammals, especially due to the fact that they take a very the fact that they take a very long time to break down.long time to break down.

◊ Studies suggest that over Studies suggest that over 60% of the debris in the sea is 60% of the debris in the sea is plastic.plastic.

Plastics and DebrisPlastics and Debris

◊ Plastic and other debris can Plastic and other debris can easily trap and get tangled on easily trap and get tangled on various marine mammals. various marine mammals. This can lead to numerous This can lead to numerous complications.complications.

◊ Marine mammals sometimes Marine mammals sometimes mistake marine debris for mistake marine debris for food and accidentally ingest food and accidentally ingest it. This can cause a blocking it. This can cause a blocking of the digestive tract, choking, of the digestive tract, choking, internal injuries, and an internal injuries, and an accumulation of toxic accumulation of toxic compounds. All of these compounds. All of these implications can be fatal.implications can be fatal.

The Plastic SeaThe Plastic Sea

◊ Due to gyres, the circular Due to gyres, the circular currents in the ocean, it is currents in the ocean, it is common for plastic and other common for plastic and other flotsam to build up in certain flotsam to build up in certain areas.areas.

◊ In the Pacific Ocean, between In the Pacific Ocean, between California and Japan, there are California and Japan, there are two linked patches of garbage two linked patches of garbage which are often referred to as a which are often referred to as a plastic soup. It is roughly twice plastic soup. It is roughly twice the size of the continental US the size of the continental US and is a threat to marine and is a threat to marine mammals.mammals.

◊ It is estimated that this plastic It is estimated that this plastic sea is the cause of death for over sea is the cause of death for over 100,000 marine mammals every 100,000 marine mammals every year.year.

OverfishingOverfishing

◊ What is What is Overfishing?Overfishing?

◊ Negative Impacts Negative Impacts on Marine on Marine MammalsMammals

What is Overfishing?What is Overfishing?

◊ Overfishing is the act of Overfishing is the act of fishing a body of water so fishing a body of water so extensively that it depletes extensively that it depletes the supply of fish in an area. the supply of fish in an area.

◊ It occurs when the quantity of It occurs when the quantity of fish harvested exceeds the fish harvested exceeds the amount that can be re-amount that can be re-supplied by growth and supplied by growth and reproduction, which results in reproduction, which results in a population collapse of the a population collapse of the target species.target species.

Negative Impacts on Marine Negative Impacts on Marine MammalsMammals◊ When fishing, commercial When fishing, commercial

fisheries often compete for fisheries often compete for the resource of fish with their the resource of fish with their natural predators. This can natural predators. This can make it more difficult for a make it more difficult for a population of marine population of marine mammals to obtain food.mammals to obtain food.

◊ Overfishing can also cause an Overfishing can also cause an imbalance in an aquatic imbalance in an aquatic ecosystem by removing one ecosystem by removing one of the links in the food chain. of the links in the food chain. This in turn can result in the This in turn can result in the decline or displacement of decline or displacement of marine mammals which marine mammals which depended on the harvested depended on the harvested fish as a food source.fish as a food source.

EntanglementEntanglement

◊ What is What is Entanglement?Entanglement?

◊ NetsNets

◊ DebrisDebris

What is Entanglement?What is Entanglement?

◊ Entanglement is a large threat Entanglement is a large threat to marine mammals. It occurs to marine mammals. It occurs when they are accidentally when they are accidentally trapped in fishing nets, fishing trapped in fishing nets, fishing lines, six-pack rings, or other lines, six-pack rings, or other snares.snares.

◊ It is estimated that hundreds It is estimated that hundreds of thousands of marine of thousands of marine mammals are entangled each mammals are entangled each year.year.

NetsNets

◊ Drift nets are one of the most Drift nets are one of the most threatening types of nets used by threatening types of nets used by fisheries. fisheries.

◊ They are essentially nets made of They are essentially nets made of thin strands of nylon that are left thin strands of nylon that are left to freely drift and catch everything to freely drift and catch everything in their path. in their path.

◊ They can sometimes be miles long They can sometimes be miles long and be left unattended for weeks.and be left unattended for weeks.

◊ Drift nets typically catch a large Drift nets typically catch a large amount of bycatch, or the non-amount of bycatch, or the non-target species that become target species that become tangled in the nets, such as tangled in the nets, such as whales, dolphins, and seals.whales, dolphins, and seals.

NetsNets

◊ Marine mammals that are Marine mammals that are trapped in these and other trapped in these and other nets will often drown if they nets will often drown if they cannot escape.cannot escape.

◊ Those that do escape usually Those that do escape usually end up with scars or missing end up with scars or missing fins as a result of being cut by fins as a result of being cut by the thin nylon strands of the the thin nylon strands of the nets.nets.

DebrisDebris

◊ Debris, such as plastic rings and Debris, such as plastic rings and fishing lines, mainly pose a fishing lines, mainly pose a threat to pinnipeds, or walruses threat to pinnipeds, or walruses and seals.and seals.

◊ These marine mammals often These marine mammals often become trapped with debris become trapped with debris around their necks or heads, around their necks or heads, which can restrict breathing, which can restrict breathing, eating, and even swimming. eating, and even swimming. Debris can also inflict physical Debris can also inflict physical wounds. At the very least, these wounds. At the very least, these negative impacts will debilitate negative impacts will debilitate their targets.their targets.

◊ Once snared, it is a very difficult, Once snared, it is a very difficult, if not impossible task for a if not impossible task for a marine mammal to remove its marine mammal to remove its bindings.bindings.

OtherOther

◊ CollisionsCollisions

◊ Climate ChangeClimate Change

CollisionsCollisions

◊ Ship traffic is another danger Ship traffic is another danger to marine mammals.to marine mammals.

◊ Those that are hit by a boat Those that are hit by a boat will often die.will often die.

◊ However, marine mammals However, marine mammals sometimes do survive boat sometimes do survive boat collisions, but will usually end collisions, but will usually end up with disfiguring wounds up with disfiguring wounds and scarring.and scarring.

CollisionsCollisions

◊ Ship strikes are not very Ship strikes are not very uncommon. Many marine uncommon. Many marine mammals have scar patterns mammals have scar patterns that indicate multiple boat that indicate multiple boat collisions.collisions.

◊ Right Whales are highly Right Whales are highly vulnerable to collisions, due to vulnerable to collisions, due to their slow surface-foraging their slow surface-foraging nature.nature.

Climate ChangeClimate Change

◊ Due to global warming, marine Due to global warming, marine mammals could lose valuable mammals could lose valuable food sources and habitats. food sources and habitats.

◊ Populations of fish, which are Populations of fish, which are preyed upon by marine preyed upon by marine mammals, are predicted to mammals, are predicted to move into deeper and cooler move into deeper and cooler water which is farther away water which is farther away from shore. This change is from shore. This change is troubling to seals and other troubling to seals and other pinnipeds that require land in pinnipeds that require land in order to reproduce and sleep on.order to reproduce and sleep on.

◊ Migratory whales could also Migratory whales could also suffer, as they are dependent on suffer, as they are dependent on finding certain resources at the finding certain resources at the ends of their migratory routes.ends of their migratory routes.

ConclusionConclusion

◊ Overall, there are many Overall, there are many threats that oppose marine threats that oppose marine mammals, such as the mammals, such as the numerous types of pollution, numerous types of pollution, overfishing, entanglement, overfishing, entanglement, ship collisions, and climate ship collisions, and climate change.change.

◊ However, these threats are However, these threats are not without hope of being not without hope of being remedied, as numerous laws, remedied, as numerous laws, regulations, and organizations, regulations, and organizations, such as the Marine Mammal such as the Marine Mammal Protection Act and the Protection Act and the creation of aquatic reserves, creation of aquatic reserves, are in place to ensure the are in place to ensure the safety and stability of the safety and stability of the marine mammal populations. marine mammal populations.