Whales In Peril: Water Pollution's Deadly Impact

Water pollution is a critical threat to whales, with plastic pollution being one of the most pressing issues. Plastics can take hundreds or thousands of years to decompose, wreaking havoc on the environment and marine life. Whales can ingest plastic, mistaking it for prey, which leads to internal injuries and excruciating deaths. They also become entangled in plastic debris, such as discarded fishing gear, resulting in drowning or extreme energy exertion. In addition, toxic chemicals in plastics accumulate in whales, impacting their health and reproduction. Oil spills, industrial pollutants, and sewage runoff further endanger whales, contaminating their food supply and disrupting their communication and navigation. With over 70% of ocean pollution originating on land, human actions are a significant contributor to the decline of whale populations.

Whales ingest plastic, which blocks airways and causes internal injuries

Marine pollution is having a devastating effect on our oceans, and 80% of it is generated by land-based activities. It is degrading habitats and directly threatening marine animals, including whales. Plastic waste is one of the most visible examples of human impact on the seas.

Whales are ingesting plastic, which blocks their airways and causes internal injuries. This is leading to the deaths of many whales. Globally, 100,000 marine mammals die every year as a result of plastic pollution. A recent study confirmed that even remote Arctic regions are not immune to our plastic garbage. Researchers examined seven beluga whales harvested by Inuvialuit hunters in Canada and reported that they had found microplastics in the digestive systems of every whale.

Whales have been found washed ashore with huge chunks of plastic inside them. In 2018, a sperm whale stranded in Indonesia was found to have ingested over 13 pounds of plastic, including bags and flip-flops. In another instance, a juvenile male sperm whale was found on Luskentyre beach with 220 pounds of plastic bags, tubing, gloves, bundles of rope, netting, tubing, and cups in its stomach.

One of the reasons whales ingest plastic is that plastic bags can look like squid to a whale. Sperm whales, for example, feed on squid and spend 70% of their lives foraging in deep waters. Plastic bags floating in the water can easily be mistaken for prey. Another reason is that whales may accidentally suck in plastics along with their prey. Yet another possibility is that whales may enjoy chewing on plastic materials and end up ingesting them.

Microplastics, in particular, are of concern. They are tiny plastic pieces of 5mm or less and are the most abundant debris floating in the marine environment. They are unlikely to obstruct the digestive tract of a baleen whale but can build up inside an animal's tissues and leach toxic chemicals that make the creature sick. These chemicals can also work their way up the marine food web over years and across generations of species, a process called biomagnification and bioaccumulation.

Marine pollution enters the whale food chain through bioaccumulation

Marine pollution is a serious threat to whales and other marine mammals. Eighty per cent of this pollution is generated by land-based human activities. One of the most visible and damaging types of marine pollution is plastic waste, which threatens marine wildlife and ends up in the seafood we eat. Plastic debris can be ingested by whales, blocking their breathing passages and stomachs, or lead to death by entanglement.

Marine pollution also enters the whale food chain through bioaccumulation. Bioaccumulation is the process by which contaminants enter the food web, passing from the environment or food to individual organisms and building up in their tissues. This occurs when organisms cannot get rid of contaminants through excretion. Some contaminants can be excreted, depending on their chemical properties and the organism.

Bioaccumulation often occurs with biomagnification, which is the process by which contaminants are passed from one level of the food chain to the next, increasing in concentration with each level. This means that those at the top of the food chain, such as whales, are the most affected by contaminants. For example, contaminants typically enter and concentrate at the base of a food web within photosynthetic organisms like phytoplankton. Zooplankton feed on phytoplankton and in turn accumulate contaminants at a higher concentration. Many zooplankton are eaten by small fish, which are then eaten by larger fish, and contaminant concentrations continue to bioaccumulate and biomagnify. Eventually, contaminants are passed from prey to the top predators of the marine food chain, such as whales, resulting in the highest levels of contaminants.

One of the most dangerous and toxic types of contaminants found in whales belongs to a group called Persistent Organic Pollutants (POPs). These include pesticides such as Dichlorodiphenyltrichloroethane (DDT) and flame retardant chemicals. Studies have shown extremely high levels of PCBs within the blubber of BC's killer whales, making them among the world's most PCB-contaminated marine mammals.

Oil spills affect whales' blubber and can be ingested through feeding

Oil spills are a major contributor to water pollution and have a detrimental impact on whales. While oil spills were once believed to be a greater risk to seabirds and furred marine mammals, they are now known to have severe consequences for whales as well. Whales and dolphins derive insulation from their blubber, which can be contaminated by oil. This contamination can occur when whales ingest oil through their prey, inhale oil fumes, or swim through oil-contaminated waters.

The ingestion of oil by whales can lead to internal problems and severe health issues. Research suggests that high doses of oil can adversely affect the nervous system of whales. Additionally, the inhalation of oil vapors can result in pneumonia and other complications. While external contamination on a whale's skin can be removed with mild detergents, the ingestion and inhalation of oil pose more serious threats to the health and well-being of these majestic creatures.

Oil spills can also indirectly affect whales by contaminating their food sources. Small animals, such as shrimp-like creatures (krill), that are part of a whale's diet, can be killed by oil spills. This reduction in prey availability can impact the nutritional intake and survival of whales. Furthermore, oil spills can cause a decline in whale populations. Research on the Exxon Valdez oil spill in Prince William Sound, Alaska, in 1989 revealed a significant and steady decrease in the number of resident killer whales in the area.

Whale blubber, a crucial source of insulation for whales, can be affected by oil spills. The contamination of blubber with oil can compromise its effectiveness in providing insulation and regulating body temperature. Additionally, oil spills can introduce toxic chemicals into the blubber, which can build up over time as whales consume more contaminated prey. During periods of stress or food scarcity, whales may break down their blubber stores for energy, releasing a flood of toxic substances into their bodies. This release of toxins can have detrimental effects on the health and survival of whales.

To mitigate the impact of oil spills on whales, various "hazing" methods are employed to deter whales from entering the contaminated area. These techniques include the use of acoustic deterrent devices that produce audible sounds for marine mammals without causing pain. However, the effectiveness of these methods varies, and capture and rehabilitation of whales affected by oil spills remain challenging.

Abandoned fishing gear entangles whales, causing injury and drowning

Abandoned fishing gear is a significant threat to whales, causing injury and drowning. This derelict gear, often referred to as "ghost gear", continues to trap and entangle marine animals long after it has been discarded. It is a common form of marine debris, with gillnets, crab pots, and traps being the most common types that continue to entrap whales and other marine life.

The impact of abandoned fishing gear on whales can be devastating. Research suggests that over 300,000 whales and dolphins die annually due to entanglement in fishing gear, with the true number likely being even higher when including unreported cases. The entanglement can cause lacerations and infections as the heavy ropes and lines cut into the flesh and bone of the trapped animals. It can also lead to drowning as the whales, unable to breathe underwater, cannot reach the surface, and to starvation as they are unable to feed effectively while towing heavy gear.

The issue of abandoned fishing gear has serious economic consequences as well. When a whale becomes entangled in fishing gear and drags it away, the gear is often lost, resulting in a financial loss for the fishers, especially for the 95% of the world's fishers who are artisanal or small-scale. Additionally, the safety of responders attempting to disentangle whales must be carefully considered, as handling injured and distressed large wild animals at sea requires specialized training and protocols to minimize risk.

To address the growing concerns around whale entanglement, the International Whaling Commission (IWC) launched the Global Whale Entanglement Response Network in 2011. This program aims to build safe and effective entanglement response capabilities worldwide, with a long-term goal of preventing entanglements altogether. As part of this initiative, experts have developed global Best Practice Guidelines and a two-day entanglement response training package to help responders safely and effectively handle entanglement incidents.

In addition to the IWC's efforts, governments and organizations are also taking steps to mitigate the impact of abandoned fishing gear. For example, a new law in California provides financial incentives for crab fishermen to collect any abandoned gear they find during the offseason, helping to reduce the amount of gear lost in the state's waters. The Global Ghost Gear Initiative (GGGI) is another global effort to address the issue, providing critical technical support to countries to prevent and manage ghost gear in their national fisheries.

Noise pollution from human industrialization and clean-up efforts harms whales

Marine pollution is a serious threat to whales and other marine mammals. Oil spills, marine debris, and industrial pollutants such as PCBs can contaminate their food supply and cause harm. However, noise pollution, a result of human industrialization and clean-up efforts, also has detrimental effects on whales.

Noise pollution in the ocean, largely from anthropogenic sound sources, has a broad spectrum of impacts on whales. These impacts include a reduction in communication range and physiological damage. For example, naval sonar can disrupt the natural diving behaviours of marine mammals, leading to mass strandings. In 2002, naval sonar use in the Canary Islands caused the stranding of 14 beaked whales. Similarly, in 2000, US Navy sonar exercises in the Bahamas resulted in the stranding of 18 marine mammals, including beaked whales, which had not previously been known to mass-strand in the area.

Commercial shipping is a major contributor to low-frequency noise pollution in the world's oceans. These large ships produce background noise over extensive geographical areas, with their engines and propellers generating significant underwater noise. Multiple airguns used during oil exploration and sonar devices to identify objects within the water column also contribute to the problem. While these efforts are essential for resource exploration and navigation, they can have unintended consequences for marine life, especially whales.

The effects of noise pollution on whales are not limited to auditory impacts. Noise can cause behavioural changes, disorientation, and even mortality in whales. It can lead to an inability to communicate effectively, detect prey, or evade predators. It also alters their natural foraging, orientation, and diving behaviours. For example, the Northern Right Whale has shown signs of chronic stress due to low-frequency commercial ship noise. Additionally, noise pollution can affect whale migration, making them more susceptible to dispersing effects like currents and reducing their navigation efficiency.

While there has been increasing recognition of the detrimental effects of noise pollution, commercial and recreational shipping remain unregulated. Voluntary guidelines have been proposed to mitigate underwater noise, but lawful implementation is yet to be achieved. As a result, whales and other marine mammals continue to be exposed to noise pollution, facing challenges in communication, navigation, and overall well-being.

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