Fast facts 2024

Contamination of river water by toxic substances

The status of contamination of river water by toxic substances is rated “good,” and has remained unchanged since 2004. Although various toxic substances were detected in most river water samples, none exceeded the guidelines for the protection of
aquatic life.

The status of the monitoring of pesticides in Lake Saint-Pierre¹ indicator is rated “moderate.” Although the frequency of detection is lower than that in 2014–2015, many pesticides are still detected in the samples, and some even exceed the guidelines for the
protection of aquatic life.

The status of safety of potential freshwater swimming sites in the St. Lawrence River¹is rated “moderate,” indicating little change since monitoring began in 2003. Approximately half of the sites consistently have good bacteriological water quality.

The status of oceanographic processes: acidity and dissolved oxygen² is rated “moderate-poor.” Therefore, the deteriorating trend that began in the 1930s has not abated, with oxygen saturation and pH values reaching their lowest levels on record.

The status of oceanographic processes: water temperature and sea ice² is rated “poor.” Since 2015, temperatures in the deep layers of the estuary and Gulf of St. Lawrence have reached record high levels since record-keeping began in 1915.

Since 2018, the status of shellfish water quality has remained “moderate-good.” The shellfish waters in the Magdalen Islands and the Lower North Shore are of excellent quality, in contrast with those in the Gaspé and Lower St. Lawrence regions, where the poor
quality restricts shellfish harvesting.

Phytoplankton communities

The status of phytoplankton communities in the lower estuary and Gulf of St. Lawrence is rated “moderategood,” with a slight deterioration since 2010. Spring phytoplankton blooms are occurring earlier than usual, with biomass values that are higher than normal.

During the 2018–2022 period, the status of zooplankton communities in the lower estuary and Gulf of St. Lawrence was rated “moderate.” The low biomass and prevalence of smaller organisms in communities have an impact on the food chain. Zooplankton are a food resource for many species, some of which are of commercial value.

Monitoring of toxic algae in the Estuary and Gulf of St. Lawrence indicates "Intermediate-Good" status, with a slight deterioration since 2010. There have been changes in the frequency and intensity of Alexandrium and Pseudo-nitzschia blooms compared with historical data.

The status of the striped bass population is rated "Intermediate-Good". Twenty years after the start of the reintroduction program for this species, striped bass in the St. Lawrence River appear to be continuing their recovery. The young are surviving, growing, and many are reaching breeding age.

The health of fish communities in fresh and brackish waters remains "Intermediate". However, status and trends vary from species to species and from sector to sector. The presence of invasive species, deterioration of aquatic habitats and poor water quality are among the factors that explain the decline of certain populations.

Among seabird populations, murres and razorbills are doing well and remain stable. The condition of the Atlantic puffin is improving, while the fragile Caspian tern population continues its timid reappearance. By contrast, the herring gull population continues to decline. The condition of this indicator is rated as "Intermediate".

The wetlands¹ indicator is rated "Intermediate", with a deteriorating trend since 1990. Agricultural activity, fluctuating water levels and the presence of invasive exotic plant species are the main pressures on wetlands.

Invasive exotic plant species are in "Intermediate" condition, with 87% of sites surveyed affected by at least one of the species monitored. Reed canary grassand purple loosestrife are the species that contribute most to the invasiveness of St. Lawrence wetlands.

Although some beluga population status indicators have improved, the beluga's condition is rated as "Intermediate-poor" and remains a cause for concern. Increased mortality of adult females and newborns has persisted since 2010.

The gannet population is in "Intermediate-poor" condition. In 2022, fewer breeding pairs were counted, and breeding success remains low and variable. On the other hand, no worrying contamination has been detected in the eggs.

Contaminants measured in Great Blue Heron eggs have all decreased compared to historical data, at all sites. In addition, values measured in 2022 were generally below established criteria. The status of this species is rated as "Good".