A perplexing mystery surrounds the recent spike in deaths of a specific southern right whale population, a group that congregates along the coast of Peninsula Valdes, Argentina.
Since 1971, scientists have been monitoring the population of these gargantuan aquatic creatures. Surprisingly, approximately 77% of all recorded right whale deaths have occurred within the past century, according to a recent publishing in the journal Marine Ecology Progress Series.
Experts are unsure as to why this number has expanded so rapidly over the past ten years, but marine biologists and veterinarians proposed three likely causes at the International Whaling Commission in 2010 – low food abundance, disease, or toxins, such as domoic acid or saxitoxin produced by harmful algae blooms.
Vicky Rowntree, the leading behavioral ecologist of the study, assures that “a lot of our research has been trying to look at those [explanations],” yet discrepancies in the analysis of right whale calf corpses further complicates the puzzle.
Only a small number of calves exhibit disease-related symptoms; nevertheless many right whale calves contain low levels of toxins. Adult right whales can tolerate the proposed toxins found in the shared krill food supply, leaving researchers to ponder the effects of toxins on the younger generations of right whales.
Another disadvantage to this southern right whale population is the impeding onslaught of kelp gull harassment, a tactic that has increased since its introduction in the 1980s. These gulls “feed on the skin they peck from the backs of the whales,” explains Rowntree. “They make a hole in the skin and they attack it over and over during the season.”
Observations have concluded that the adult southern right whales have learned to avoid the bird’s attacks, but the calves continually fail to evade their attackers. As a result, “most calves have a chain of lesions along their backs from being pecked by the gulls,” reports Rowntree from the Instituo de Caonservacion de Ballenas in Buenos Aires, Argentina. For now, this team of ecological experts is continuing to monitor the Valdes right whale food consumption, in hopes of finding the source of this population’s perilous decline.
Puzzling queries are abundant in the field of science, which is why I find environmental science especially enthralling – questions always appear alongside newly revealed answers. Unfortunately, in the case of the Peninsula Valdes Argentina southern right whale population, this mystery concerns the livelihood of the species. I found the possible kelp gull harassment theory rather fascinating, although I shouldn’t be as alarmed by this natural predator-prey relationship as I am. Perhaps the sores and cuts along the calves’ skin is suppressing the animals’ immune system, leaving them susceptible to toxins that reside within the ocean waters. I believe a combination of threats is likely linked to the sharp decline of southern right whale calves, since nature impacts (and is impacted by) multiple factors that occur simultaneously. However, I would suggest an inspection of harmful pollutants that may reside in the water, as a possible contributor to the right whale population decline. Toxins may lurk in algae blooms wake, but pollutants from nearby towns and fisheries is a possibility, as well.
Lee, Jane J. “Mysterious Deaths Threaten a Population of Southern Right Whales.” National Geographic. N.p., 1 Dec. 2013. Web. 3 Jan. 2014.
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