Reducing the threat of contaminants to St. Lawrence Estuary Belugas

The St. Lawrence Estuary Beluga is loved by local communities and recognized worldwide. It is also one of Canada’s most endangered whale populations. While recent years show some signs of stabilization, the population remains fragile and continues to face multiple pressures that hinder recovery.

Key threats to recovery include:

vessel noise and disturbance
reduced prey availability and quality
habitat degradation
environmental contaminants

The Government of Canada listed the St. Lawrence Estuary Beluga population as threatened under the Species at Risk Act (SARA) in 2005, and in 2012, prepared the Beluga whale (Delphinapterus leucas), St. Lawrence Estuary population, recovery strategy. Following a reassessment of the population in 2014 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), the beluga’s status was reclassified as endangered in 2017. Two action plans detailing concrete measures to advance recovery were published:

As the federal lead on environmental pollution under the Whales Initiative, Environment and Climate Change Canada (ECCC) is advancing targeted science and actions to mitigate exposures to contaminants and support the long‑term health and recovery of this iconic species.

Contaminants and St. Lawrence Estuary Beluga

The St. Lawrence Estuary Beluga population lives downstream from the densely populated Great Lakes – St. Lawrence and Saguenay River regions where major agricultural and industrial activities take place. As a result, these whales have been exposed to a wide variety of contaminants for decades. Once released into the environment, these chemicals travel downstream throughout the watershed, accumulate in living organisms and sediments, and can become concentrated in the Estuary.

Contamination of the aquatic environment comes from many sources, including agricultural, industrial and municipal waste, maritime shipping, dredging, resource extraction, and aquaculture, among others. These pollutants enter the St. Lawrence and can affect marine mammals and the prey they depend on.

For belugas, contaminants remain a major concern, particularly long‑lasting industrial chemicals and emerging pollutants. These substances accumulate in their tissues through the foods they eat, a process known as bioaccumulation. Over time, these contaminants can affect reproduction, immunity, and calf survival.

The Recovery Strategy for the St. Lawrence Estuary Beluga provides an overview of the principal groups of chemical compounds that have been found in belugas and their habitat, including:

Polychlorinated biphenyls (PCBs)
Organochlorine Pesticides (dichloro-diphenyl-trichloro-ethane or DDT, Aldrin, Chlordane, Dieldrin, Endrin, Heptachlorocyclohexane or HCH, Hexachlorobenzene or HCB, Mirex, Toxaphene)
Dioxins and furans
Tris(4-chlorophenyls)
Chlorinated paraffins/alkanes
Organotins (tributyltin oxide (TBT), Dibutyltin (DBT) and Monobutyltin (MBT))
Polybromodiphenylethers (PBDE, a type of flame retardant)
Perfluorinated Compounds (Perfluorooctane sulphonate (PFOS))
Polycyclic aromatic hydrocarbons (PAHs- benzo-α-pyrene)
Current-use pesticides (For example, atrazine)
Heavy metals (mercury, lead, cadmium)
Pharmaceuticals and Personal Care Products (PPCPs)

Further information is available through reports and datasets produced by ECCC’s environmental monitoring programs through the Whales Initiative.

There is significant overlap between the contaminants identified in St. Lawrence Estuary Belugas and those affecting the Southern Resident Killer Whale, another of Canada’s endangered whale species. This overlap underscores the widespread nature of these substances and the importance of coordinated efforts to reduce contaminant levels in marine ecosystems.

Environment and Climate Change Canada’s actions to protect St. Lawrence Estuary Belugas from contaminants

Through participation in the Whales Initiative, ECCC focused on targeted monitoring, research, and collaborative efforts with the aims of:

finding out how and where contaminants enter aquatic environments
better understanding contaminant threats and reducing their impact on St. Lawrence Estuary Belugas
improving management of certain chemicals that affect whale health
educating people about what they can do to protect whales from contaminants

Environmental monitoring

ECCC’s research and monitoring activities helped reveal more about how and where contaminants enter aquatic environments. Between 2018-2023, ECCC collected samples in and around the St. Lawrence River and Estuary from wastewater treatment plants, air, and landfill sites. Monitoring focused on areas located in, or known to be closely connected to, St. Lawrence Estuary Beluga critical habitat.

From 2023 to 2026, wastewater and air sampling continued. Additional multimedia monitoring was introduced during this time to sample and assess sediment, water quality, and biota in the main tributaries to the St. Lawrence Estuary Beluga’s critical habitat. (For reference, biota means ‘living things.’ In this monitoring program, the biota sampled were clams, worms, and other bottom‑dwelling animals that belugas eat or that act as indicators of environmental health).

Three sectors—Quebec City, the Saguenay River, and the Cacouna region—were studied, covering 21 sites important to the St. Lawrence Estuary Belugas to better understand the transport and fate of contaminants of concern.

Further environmental monitoring information is available in:

Reports and datasets produced by ECCC’s environmental monitoring programs through the Whales Initiative
Freshwater, sediment and biota data from the Whales Initiative in the St. Lawrence River and Estuary region
long-term water quality monitoring data in the St. Lawrence River basin

Contaminant research on St. Lawrence Estuary Belugas

ECCC researchers, in collaboration with Fisheries and Oceans Canada (DFO) and universities, carried out work to study how contaminants build up in St. Lawrence Estuary Belugas and how the population becomes exposed by eating contaminated prey.

A non-exhaustive list of relevant published papers (2018 to 2025) is provided below:

Contaminants networking group

Established in June 2022 by ECCC, the Contaminants Working Group (CNG) brought together stakeholders from all levels of government, Indigenous organizations, academia, and NGOs with diverse expertise related to contaminants. The aim of the CNG was to support knowledge sharing and collaboration on contaminants affecting St. Lawrence Estuary Belugas, their prey, and habitat.

Objectives of the CNG included:

Providing a forum for sharing knowledge among experts working to reduce the threat of contaminants
Encouraging open and free discussions among invited participants and guests
Supporting collaboration between organizations to facilitate concerted efforts to reduce contaminant threats to St. Lawrence Estuary Belugas, their prey, and habitat

More information

For further information, contact: enviroinfo@ec.gc.ca.

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2026-05-06

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