The beluga whale (Delphinapterus leucas), also known as white whale for their distinct all-white colour, is an Arctic and sub-Arctic marine mammal. It possesses a distinctive organ at the front of its head called melon, which is used for echolocation. The size of a beluga whale is between that of a dolphin’s and a true whale’s (Wikipedia).
Image Source: National Geographic (http://animals.nationalgeographic.com/animals/mammals/beluga-whale/)
Historically, the beluga whale had a population size of about 10,000 individuals (during the 1800s) in the St. Lawrence Estuary (SLE) but currently (2003) about 1100 individuals live there (DFO, 2005).
The prime cause of their disappearance, hunting, was banned in 1979. Naturally, the population would have been expected to increase since then, but no clear sign of recovery is seen (Lebeuf et al., 2007).
Martineau et al. (2002) reported that they studied 129 beluga carcasses out of 263 reported stranded between 1983 and 1999. They found 27% of the adult belugas had cancer. The annual rate of all cancer types was much higher than any other population of cetaceans and was similar to that of humans.
High concentration of PAH(polycyclic aromatic hydrocarbons) were found in the Saguenay River sediments (500-4500 ppb of total PAH); which is a part of SLE beluga habitat. These compounds originate mainly from upstream aluminum smelters. The invertebrates living in the bottom sediment accumulate PAHs and they form a significant amount of SEL beluga diet.
High rates of cancer among workers in aluminum plants have been related to PAHs epidemiologically. Martineau et al. (2002) suggested from these studies that PAHs are related to high rate of cancer in SLE belugas.
Metcalfe et al. (1999) showed that total PCB (Polychlorinated biphenyl), DDT (dichlorodiphenyl-trichloroethane) and Chlordane concentrations in SLE beluga tissues were higher compared to the Canadian Arctic belugas; which reflects the input of these chemicals into the St. Lawrence river.
A temporal trend analysis of persistent, bioaccumulative and toxic (PBT) chemicals on these whales showed that concentration of most of the PBTs in SLE beluga have decreased between 1987 and 2002; while no increasing trends were observed either (Lebeuf et al., 2007).
Yet, concentration of the toxic chemicals in beluga tissues are not decreasing quickly and new persistent contaminants are being introduced to the aquatic ecosystem. So, these contaminants accumulate in juveniles and adults through the food and in calves through their mothers. There are other threats to the beluga population too, which include marine traffic, anthropogenic noise, reduced fish population, habitat destruction etc. (DFO, 2012)
Recent news report says that since 2008, there has been an increase in the mortality rate of beluga whale calves. The report quoted Robert Michaud, scientific director of the Groupe de recherche et d’éducation sur les mammifères marins (GREMM), who informed that since 2005, along with increasing mortality rate of calves, a lot of female belugas are dying during, before or after giving birth. He also informed that, there has been no surveys since 2009 (CBC News, 2013).
Image Source: CBC News, 2013.
Fisheries and Oceans Canada proposed long-term mitigation measures to restore the beluga whale population to 70% of its historical size (7070 individuals), but with current growth rate of 1% it will take until 2100 to reach that goal (DFO, 2012).
Fig: The Saguenay-St. Lawrence Marine Park and the two proposed marine protected areas (MPAs), the proposed Manicouagan marine protected area and the proposed St. Lawrence Estuary Marine Protected Area. Inset: the location of the area in Quebec. (Source: DFO, 2012).
There is lack of study that correlates organic chemicals in beluga tissues to the source of these chemicals. Proper monitoring and management plan for industrial development activities needs to be adopted. Cumulative effects assessment of the St. Lawrence River watershed might help us to identify and minimize the negative impacts of the toxic chemicals on the St. Lawrence River ecosystem.
The question comes to mind, who to blame? Are the industries only responsible for the pollution?
Leave your word below.
Beluga whale. In Wikipedia, The Free Encyclopedia. Retrieved October 08, 2013, from http://en.wikipedia.org/w/index.php?title=Beluga_whale&oldid=576379085
CBC News. 2013, August 20. Beluga deaths in St. Lawrence worry whale researchers. Retrieved October 8, 2013, from http://www.cbc.ca/news/canada/montreal/beluga-deaths-in-st-lawrence-worry-whale-researchers-1.1346616.
DFO. 2005. Recovery potential assessment of Cumberland sound, Ungava Bay, Eastern Hudson Bay and St. Lawrence beluga populations (Delphinapterus leucas). DFO Can Sci Advis Sec Sci Advis Rep 2005/036, 14 pp. Available at http://www.dfo-mpo.gc.ca/csas/Csas/status/2005/SAR-AS2005_036_e.pdf; 2006.
DFO. 2012. Recovery Strategy for the beluga whale (Delphinapterus leucas) St. Lawrence Estuary population in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada, Ottawa. 88 pp + X pp. Available at http://www.sararegistry.gc.ca/virtual_sara/files/plans/rs_st_laur_beluga_0312_e.pdf
Lebeuf, M., M. Noël, S. Trottier and L. Measures. 2007. “Temporal trends (1987-2002) of persistent, bioaccumulative and toxic (PBT) chemicals in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada.” Science of the Total Environment 383: 216-231.
Martineau, Daniel, Karin Lemberger, André Dallaire, Philippe Labelle, Thomas P. Lipscomb, Pascal Michel and Igor Mikaelian. 2002. “Cancer in Wildlife, a Case Study: Beluga from the St. Lawrence Estuary, Québec, Canada.” Environmental Health Perspectives 110: 285-292.
Metcalfe, C., T. Metcalfe, S. Ray, G. Paterson and B. Koeniga. 1999. “Polychlorinated biphenyls and organochlorine compounds in brain, liver and muscle of beluga whales (Delphinapterus leucas) from the Arctic and St. Lawrence estuary.” Marine Environmental Research 47: 1-15.