St. Lawrence beluga
In 2014, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) uplisted the St. Lawrence beluga to “endangered”. These experts, who review the status of Canadian wildlife species every ten years, argue that this small population now faces a considerably higher risk of extinction than in 2005. To learn more: Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Beluga Whale, St. Lawrence Estuary population
Experts from various backgrounds had previously teamed up to develop a recovery strategy in compliance with the Species at Risk Act, with the aim of better understanding threats to the beluga and proposing strategies to bring its population up to a threshold where its survival will no longer be threatened by natural or human-induced disturbances.
What follows is a summary of the strategy prepared by Whales On Line..
Historic whaling aside, the life strategy (life expectancy, late maturation and low annual rate of reproduction) and low genetic diversity of the beluga are limiting factors to the recovery of the St. Lawrence population. If a major die-off were to occur, the population’s return to its current level would be very long in comparison to other species having a shorter generation time, and the low genetic diversity could render the animals’ immune system less effective, making them more prone to pathogenic agents and chemicals. Natural factors such as emigration and predation can also lead to the loss of some individuals.
The recovery of the St. Lawrence beluga population is achievable. In the long term, the goal is to reach a population of 7,070 individuals, which corresponds to 70% of the original population. To reach this population size, the recovery objectives are as follow:
- Reduce toxic contaminants in the St. Lawrence ecosystem that might inhibit its recovery
- Reduce disturbance caused by human activities
- Ensure accessible and adequate food resources for belugas
- Mitigate the impact of other threats on the species’ recovery
- Protect beluga habitat throughout its entire range
- Conduct regular monitoring of the beluga population in the St. Lawrence Estuary
Pursuant to examination of beluga carcasses found on the shores of the St. Lawrence since 1982, significant concentrations of PCBs, DDT, Mirex, mercury and lead have been measured, as have signs of exposure to PAHs. These products are well known for their toxic effects on animal life and their impact on the reproductive and immune systems. Even after their use is banned or their emissions are curbed, many contaminants persist in the environment for decades. Nevertheless, reductions have been observed for some contaminants such as DDT and PCBs. Other compounds have entered the scene in a big way, including polybrominated diphenyl ethers (PBDE), which are flame-retardant compounds. PBDE concentrations in the tissues of belugas rose exponentially in the 1990s.
Why so much?
Given their feeding habitats and their position in the food chain, belugas accumulate large concentrations of contaminants. They feed on small and medium-sized fish as well as invertebrates living near the sediment. Belugas thus ingest contaminant “concentrates” and become a reservoir for these persistent chemicals. Despite recent reductions of toxic spills, the contaminant levels measured in belugas are not falling as rapidly as those in the environment. Adults continue to accumulate contaminants through their diets, while calves receive extremely high doses throughout gestation and nursing. This transfer of contaminants hampers the beluga decontamination process.
Furthermore, high rates of disease (infections and cancers) are observed in examined carcasses. Also, cancer rates observed in St. Lawrence belugas are much higher than in Arctic belugas, which are far less contaminated, or any other species of wild mammal. Moreover, the frequency of these diseases suggests that the St. Lawrence belugas’ immune systems may be being undermined by exposure to toxins. Lastly, carcass analysis leads to believe that contamination may affect the beluga’s reproductive system, which could diminish the production of offspring and thereby hinder this population’s recovery.
To survive and reproduce, any animal requires a little peace and quiet to perform its vital activities! If disturbance is recurrent and affects many individuals, the very survival of the population may be jeopardized. Significant maritime traffic in the zone frequented by St. Lawrence belugas is a potential source of disturbance. This traffic includes thousands of ships going up and down the St. Lawrence and Saguenay Rivers: ferries, fishing vessels, recreational boats of all types and whale-watching boats. The number of whale-watching excursions – including plane and helicopter tours – has surged since the early 1980s.
Boat traffic may interfere with the beluga’s daily activities such as hunting, movement and social behaviour, as well as the bonds between mothers and their calves. The presence of these vessels also increases the risk of collision. Belugas may also be affected by noise generated by commercial shipping, whale-watching, recreational boating and aerial tours. Recent studies have demonstrated that at certain locations and at certain times, maritime traffic noise is so intense that St. Lawrence belugas may sustain damage to their ears. This whale has a well developed sense of hearing and echolocation system, both of which are essential for finding food, navigating and communicating.
Other habitat degradations
Belugas spend a great deal of time near the coasts. During the summer months, they are extremely faithful to certain sites in the St. Lawrence Estuary as well as in the Saguenay. These habits expose belugas to coastal human activities such as dams, construction of marinas and wharves, dredging as well as other projects associated with the growing tourism industry. To date, no case of site abandonment has ever been satisfactorily documented. Nevertheless, the absence of belugas in the Manicouagan Banks region might possibly be explained by changes in habitat following construction of hydroelectric power plants on the Manicouagan and Outardes Rivers in the 1960s. It is impossible to verify this hypothesis, however, since no data are available on the characteristics of this habitat prior to construction of the dams. On the other hand, some believe that the current absence of belugas here can be better explained by historic overhunting of the species in the region. A similar theory has been formulated to explain the absence of belugas in Tadoussac Bay, a site formerly patronized by belugas and which has been considerably altered in the wake of the substantial development of the tourism industry. Dredging work, normally performed to increase the depth and width of shipping lanes and which accompanies marina construction projects, can resuspend contaminants contained in the sediment. Every year, dredging is carried out near the Rivière-du-Loup wharf, near a site frequented by belugas, and throughout the St. Lawrence. The scale of these dredging operations will probably not decrease, judging by the size of the ships entering and leaving the St. Lawrence. Seismic exploration and oil and gas development generate high noise levels as well as a number of effects on the ecosystem as a whole. These activities are prohibited in the St. Lawrence Estuary, but permitted in the Gulf of St. Lawrence, which belugas are likely to frequent in the winter. Lastly, the introduction of exotic species by way of the ballast water from freighters represents an issue of global proportions that can alter the species composition of an ecosystem.
Reduction in the abundance, availability and quality of the food resource
The repercussions that fishing might have on belugas are not well understood. The collapse of commercial fish stocks might shift efforts to other fish species, thereby putting greater pressure on the beluga’s prey. Likewise, the recent increase in the numbers of gray and harp seals will perhaps result in a reduction in the availability of prey. Fiercer competition for prey is also feared if climate change extends the season tolerable to seabirds and other animals poorly suited for the ice conditions of the St. Lawrence. However, without reliable data on the diets of belugas and other marine mammals, it is difficult to quantify the degree of competition for food resources.
In the Gulf of St. Lawrence, fishermen regularly report incidental catches involving harbour porpoises and, more rarely, other cetacean species. Bycatch in fishing gear is more uncommon in the beluga’s summer range. Since the beluga carcass recovery program was implemented in 1982, fewer than five cases of entanglement of belugas in fishing gear have been reported in the St. Lawrence Estuary. If belugas seldom get caught in fishing gear, it is probably attributable to the minor importance of the fishing industry in the beluga’s summer range, the limited use of gillnets as well as the species’ exceptional echolocation abilities. The risks of entanglement can be far more significant for animals that venture outside their usual sector, however, where fishing is more prevalent.
- Beluga caught in longline gear
- Photo credit : © GREMM
The St. Lawrence Estuary is used by a number of boat types that have the potential to enter into collisions with belugas; encounters can be fatal, cause injury and affect the survival of individuals. Belugas are probably more vulnerable to tour and recreational watercraft than to merchant vessels, the former having highly variable speeds and directions. The curiosity shown by belugas toward these watercraft further aggravates their vulnerability. Several belugas of the Estuary show injuries and scars in all likelihood attributable to a ship strike. Thanks to photo-identification, these marks are used today to differentiate belugas.
Few significant spills have occurred in the St. Lawrence to date. The Estuary being a semi-enclosed habitat, the consequences of a spill may be more detrimental than compared to the sea. Potential problems include the release of gases through evaporating surface oil which can damage certain fragile organs, as well as possible ingestion of a portion of the oil through contaminated prey. These problems are believed to be even more acute in winter, since oil tends to accumulate near the ice, where belugas spend a great deal of their time. This threat is thus considered to be potentially very dangerous for the St. Lawrence beluga population.
The main potential source of epidemics is viruses. In particular, the morbillivirus is believed to have caused the deaths of hundreds or even thousands of seals and cetaceans in the world. Although the St. Lawrence seals examined through 1999 had antibodies against the morbillivirus (a sign of exposure to the virus), no antibodies were found in the belugas studied. Two possible explanations exist for this absence: either belugas have never been exposed to the morbillivirus or they are resistant to it. In the first scenario, the population of St. Lawrence belugas would be highly vulnerable to an epidemic if it were to come into contact with these viruses. If they are not resistant, a morbillivirus epidemic in the St. Lawrence beluga population could be fatal given the small size of the population. Also, given the possibility that belugas’ immune systems are being affected by exposure to a number of contaminants, their vulnerability to such diseases might be exacerbated. Other pathogens such as the bacteria Brucella and the protozoan Toxoplasma gondii can also cause infectious diseases in belugas.
Toxic algal blooms
In the summer of 2008, a red tide extending 600 km2 struck the St. Lawrence Estuary and is believed to have caused the deaths of ten belugas. The proliferation of the toxic alga Alexandrium tamarense caused the death of several cetaceans, dozens of seals and thousands of birds, invertebrates and fish. Ingested through prey, the alga produces a neurotoxin that paralyzes the animals, resulting in asphyxiation. Eutrophication, climate change and the ensuing alteration of rainfall patterns may result in increased algal blooms, making this phenomenon a more significant threat to the St. Lawrence beluga.
Due to their threatened status, St. Lawrence belugas have been the subject of a number of scientific studies. Placement of recorders, photo-identification, performance of biopsies, and monitoring of herds on the water or from the coast; such research, though indispensable for acquiring knowledge of belugas, also has the potential to disturb them. Research work with the potential to disturb marine mammals requires a permit from Fisheries and Oceans Canada at all times and from Parks Canada when the study is conducted within the Saguenay-St. Lawrence Marine Park.
Hunting is considered to be the primary factor responsible for the decline of the St. Lawrence beluga, with thousands of individuals having been harvested at the end of the 19th century. Hunting is now prohibited and poaching is no longer considered to be a problem.
1. Reduce toxic contaminants in the St. Lawrence ecosystem that might inhibit its recovery
The recovery strategy work team recognizes that in order to facilitate the recovery of the beluga population, it is essential to further restrict quantities of harmful substances in the St. Lawrence and Great Lakes ecosystem from effluents and the atmosphere; to continue research efforts to better understand the impact of these contaminants as well as their evolution in the tissues of belugas and their prey; to take measures to minimize the recirculation of contaminants already present in the system (notably in sediment) and the introduction of new contaminants; and to pursue the clean-up of contaminated terrestrial and aquatic sites in the St. Lawrence and Great Lakes watershed.
2. Reduce disturbance caused by human activities
LThe recovery strategy presents strategies that aim to reduce disturbance and favour a viable cohabitation between belugas and humans. To succeed in this challenge, a better understanding of the impacts that disturbance and noise pollution have is essential, as are adopting, reviewing and applying protection measures to sites heavily used by belugas. The importance of not disturbing belugas should be publicized and measures should be taken to ensure that belugas do not become targets for whale-watching cruises.
3. Ensure accessible and adequate food resources for belugas
Spawning and nursery areas as well as the migratory routes for the beluga’s prey should be protected, research on beluga diets should be pursued, and new fisheries that might have an impact on belugas or their prey should be averted.
4. Mitigate the impact of other threats on the species’ recovery
Measures to mitigate the effects of the multiple threats hindering the recovery of the St. Lawrence beluga population include developing and implementing adequate protection measures for coastal projects; maintaining the Quebec Marine Mammal Emergency Response Network; monitoring fishing gear incidents; maintaining and improving the carcass recovery program, with a particular focus on the causes of mortality; and elaborating emergency response plans for spills, algal blooms and epizootics.
5. Protect beluga habitat throughout its entire range
It will be essential (i) to pursue research efforts to further knowledge of those zones heavily used by belugas (according to the seasons) as well as the threats to these habitats, and (ii) to implement protection measures using various legal tools (marine protected areas, zoning plan, etc.).
6. Conduct population monitoring
It is critical that the St. Lawrence beluga be monitored in order to detect any improvements or deteriorations in the status of the population. This implies conducting population censuses no less than every three years and studying beluga carcasses retrieved, which to date have been the main source of information on beluga biology (diseases, contaminant concentrations, age at time of death, etc.). The structure and size of the population must also be studied in order to detect trends, understand mortality patterns and identify recruitment problems. Data collected from live animals should help shed light on the relationships between contaminants and various health indicators.