Threats

The rise in vessel traffic along the British Columbia Coast has negatively impacted cetaceans, altering their behaviors and endangering their survival. Large and small vessels disrupt crucial activities like foraging, feeding, socializing, and breeding, affecting the energy intake and population-level consequences for species like killer whales. Underwater noise generated by motorized vessels impairs the ability of whales to communicate, navigate, rest, and detect prey, leading to stress, disrupted activities, and avoidance of noisy areas.

Vessels also emit harmful exhaust and pollutants like sulfur dioxide, particulate matter, and nitrogen oxides, posing risks to cetaceans. These pollutants enter their bloodstream more rapidly during diving and certain weather conditions can trap pollutants at the ocean's surface, affecting their breathing. The cumulative effect of vessel disturbance is significant, with critical habitats facing multiple recreational boaters, whale-watching boats, and heavy shipping traffic, often non-compliant with guidelines. Such disturbance incidents occur at a rate of approximately 100 per day during peak seasons, leading to population declines in other regions.

Even self-propelled vessels like kayaks can disturb cetaceans, particularly in heavily-used recreational areas. The increasing vessel traffic presents a serious threat to the conservation and well-being of cetaceans along the British Columbia Coast. Learn what measures you can take by following the Be Whale Wise guidelines while boating in BC and Washington State.

Cetaceans in British Columbia face a significant risk of injury and mortality from vessel strikes. A study by the B.C. Marine Mammal Response Network found that smaller vessels were responsible for most collisions, while strikes involving larger vessels were likely underreported. Humpback whales and fin whales are particularly vulnerable, with humpback whales having the second-highest strike rate among whale species in B.C. and fin whales being the most commonly struck cetacean species worldwide. The feeding behavior of these species near the surface and their presence in shipping lanes puts them at risk.

Reducing vessel speed in areas of common cetacean activity is crucial in mitigating strikes. Studies have shown that reducing speeds to below 10 knots significantly decreases the likelihood of vessel strike. Large and fast-moving vessels pose a higher risk, and it's worth noting that vessel-cetacean collisions also endanger boaters.

To address this issue, the Ocean Wise Sightings Network has introduced the WhaleReport Alert System. This system uses real-time sightings reported through the WhaleReport app to alert large commercial vessels of nearby whales, enabling them to take adaptive measures such as slowing down or changing course to reduce the risk of collision and disturbance. Sightings reported by coastal residents and mariners play a vital role in identifying high-risk areas and understanding the distribution of cetaceans.

Entanglement in fishing gear poses a significant threat to cetaceans globally, including whales, dolphins, and porpoises. It restricts their movement, causes injuries, and can even lead to drowning. Worldwide, over 300,000 small cetaceans die each year due to entanglement, with species like the vaquita and Maui's dolphins at high risk of extinction. In British Columbia, the extent of entanglement is not well-studied, but it is known to affect species like harbour porpoises and large baleen whales. Humpback whales, in particular, are prone to entanglement due to their morphology and near-coastal migration patterns. The Marine Mammal Incident Response Network in British Columbia has been established to address entanglement incidents and other threats to local cetaceans. Quick response efforts have shown success in disentangling whales. Similar programs exist in other regions, such as the Whale Release and Stranding Network in Newfoundland and Labrador, which collaborates with fishermen to find solutions to the entanglement problem.

The food supply for cetaceans is influenced by various factors, including overfishing, climate change, underwater noise, and human activity, which can have significant effects on their health and foraging success. Determining the diet of cetacean species is a complex task, with researchers using techniques such as analyzing prey samples and studying stomach contents. For example, studies have shown that resident killer whales have a diet consisting primarily of salmon, particularly Chinook salmon, which is preferred due to its size, fat content, and year-round availability. The decline in Chinook salmon abundance has been linked to periods of killer whale population decline. The importance of other prey species to the survival of different cetaceans is not well understood, but suboptimal prey availability can lead to nutritional stress and make them more susceptible to illness and contamination. The reduction in prey availability due to competition with fisheries, climate change, or other factors is a significant concern for at-risk cetaceans. It is essential to address these issues to ensure the well-being and conservation of cetacean populations.

Depredation (removal of fish caught on fishing lines) by toothed whales is a widespread problem in many oceans around the world. Negative impacts of depredation include economic losses to fishermen, increased pressure on fish stocks, and injury or mortality to whales.

Depredation by toothed whales like killer whales and sperm whales is a global problem causing economic losses for fishermen and impacting fish stocks, while also posing risks to the whales themselves. In British Columbia, depredation incidents are increasing among halibut, black cod, and salmon fishermen, primarily in hook and line fisheries. Other fishing methods can contribute by discarding offal and releasing bycatch in the presence of whales. The intelligence and social behavior of cetaceans make it challenging to eliminate learned depredation behaviors that can spread within populations. Prevention is crucial, requiring collaboration among fishermen, scientists, and managers to minimize the impact on fisheries.

Depredation results in significant economic losses, estimated at tens of thousands of dollars per day for some fishermen. While gear damage is minor, the loss of catch is a pressing concern. In BC, depredation incidents by killer and sperm whales are rising, particularly affecting commercial salmon trollers and sport fishers targeting chinook and coho salmon. Reporting incidents is vital to gather more information on the extent of the problem.

Both killer whales and sperm whales are protected species under the Species-at-Risk Act in BC. Efforts to address depredation include past symposiums and workshops, leading to the formal recording of events through Pacific Halibut Commission logbooks. This data aims to establish a baseline and track patterns. The key focus is to prevent depredation from becoming widespread.

Addressing depredation requires proactive measures, cooperation, and ongoing monitoring to mitigate its impact on fishermen and whale populations.

Killer whales, as apex predators, are highly contaminated due to the accumulation of Persistent Organic Pollutants (POPs) from their prey. These toxins are difficult to eliminate and are stored in the thick blubber of cetaceans. Studies have found that killer whales are among the most contaminated marine mammals globally, with Bigg's (transient) killer whales, which feed on marine mammals, having the highest levels of PCBs. PCB concentrations and other pollutants increase with age in both resident and transient killer whales. The transfer of contaminants from female to calf occurs during gestation and nursing, with the first-born calf receiving the highest load. This transfer reduces the contaminant load in females, but it means that juveniles can have higher POP levels than their mothers. The foraging location also affects the contaminant load, with southern resident killer whales having higher toxin levels due to consuming Chinook salmon from near-urban waters with higher pollution. Even in the Arctic, seemingly untouched by human activities, top predators and baleen whales accumulate large amounts of contaminants. Limited prey availability exacerbates the issue, as fat stores containing POPs are mobilized during food shortage, leading to higher concentrations of toxins in the body. This situation affects the survival and reproductive success of cetaceans, such as southern resident killer whales.

In the North Pacific, underwater noise has doubled in intensity every decade for the past 60 years. Noise from shipping, seismic exploration, and military sonar contribute to underwater noise and may impact the ability of cetaceans (whales, dolphins, and porpoises) to conduct critical life processes such as foraging, finding mates, and navigating through their underwater environment. This impacts various species of whales in different ways.

Toothed whales:

Toothed whales rely on echolocation and acoustic communication for foraging, navigating, and socializing. Acoustic disturbance from sources like vessel noise and construction disrupts these crucial processes, affecting their ability to find prey, maintain group cohesion, and engage in mating behaviors. Species that live in shallow coastal areas are particularly vulnerable due their overlap with human activity. Slowing down vessel speed has shown promising results in reducing underwater noise, with a trial in Haro Strait demonstrating a significant reduction in vessel noise levels and ambient noise when ships voluntarily reduced their speed. These findings support speed reduction as an effective measure to mitigate the impact of vessel noise on killer whale populations in the Salish Sea.

Baleen whales:

Ambient noise from human activities can mask the low-frequency calls of baleen whales, which are crucial for their social communication. The increasing levels of low-frequency noise from shipping, seismic exploration, and military sonar pose a significant threat to the recovery of blue, fin, and humpback whales in British Columbia, as it can hinder their vocalizations and disrupt their habitat.

Offshore species:

Offshore species, including beaked whales such as Baird's and Cuvier's beaked whales, are susceptible to the negative impacts of noise pollution. Anthropogenic noises in offshore environments like seismic exploration and military sonar can disturb and harm these whales, as evidenced by strandings and necropsies indicating gas-bubble disease caused by their behavioral responses to noise. Avoidance behaviors exhibited by Cuvier's beaked whales, such as intense swimming and reduced surface durations, increase their vulnerability to gas bubble embolism.

The history of whaling in British Columbia has had lasting effects on cetacean populations. From 1866 to 1875, European whaling ships targeted grey whales and North Pacific right whales for their oil, depleting their numbers to the point of commercial inviability. Humpback whales were also hunted during this time, but their population has since recovered. The introduction of steam-powered ships and explosive harpoons in the 20th century led to the first and second modern era of whaling, resulting in the removal of at least 24,862 whales from B.C. waters by 1967.

The North Pacific right whale population remains critically endangered despite legal protection, with an estimated 30 individuals remaining. Blue whales and fin whales were heavily targeted, with their populations severely reduced. Sei whales, once common in B.C. waters, are now scarce, and only around 100 individuals are taken annually by Japan. Grey whales have shown a slow recovery, with around 20,000 individuals estimated in the Eastern North Pacific. Humpback whales have made a remarkable recovery, with their population rebounding to at least 18,302 whales in the North Pacific.

Sperm whales were heavily hunted for their oil, but their population in the North Pacific now stands at approximately 80,000 and is not considered at risk. Killer whales were not targeted by commercial whaling but were impacted by live-capture operations. Northern and southern resident killer whales are listed as threatened and endangered, respectively, in B.C.

Today, aboriginal subsistence whaling continues in certain regions, recognized by the International Whaling Commission as different from commercial whaling. Special Permit Whaling, also known as "scientific whaling," is still practiced, with Japan issuing permits for research purposes. Japan's new proposal for a special whaling program in the North Pacific has faced criticism from the IWC's expert panel.