A humpback whale breaching in the Gulf | Photo courtesy of the Mingan Island Cetacean Study
The Mingan Island Cetacean Study was founded in 1979 on the northern shore of the St Lawrence Gulf, a semi-enclosed sea bordered by all four Maritime provinces and the far reaches of eastern Quebec. For 36 years now, this independent research organization has kept a watchful eye on the species of whale calling these waters home.
Among the gentle giants visiting the Gulf each spring are fin and humpback whales, returning from their wintering grounds in pursuit of a good meal. In the chilly waters of Atlantic Canada they hunt krill and small fish such as herring and capelin.
Calling on their data from 1984-2010, the Mingan Island Cetacean Study (MICS) has discovered something extraordinary about the seasonal migrations of these two species. They have been arriving at their feeding grounds in the Gulf, on average, a full day earlier each year. Taken over the lifetime of this study, fin and humpback whales are visiting Atlantic Canada a full month earlier than they did historically.
“This one month shift over about 30 years is actually amazing,” said Christian Ramp, long time MICS researcher and a lead author of their recent paper. A migrational shift of this magnitude and speed has never been documented before making MICS’ 27-year study the first of its kind. The force causing this unprecedented shift isn’t difficult to guess — a changing climate.
In order to appreciate the link between climate change and the migration of whales, we must look to the bottom of the food chain — to the microscopic phytoplankton, which form its foundations. These biological solar panels bloom in such unspeakable numbers that their congregations can be seen from space, swirling with the currents of the ocean and setting marine ecosystems into motion. Species of zooplankton, such as krill, feed on phytoplankton and bloom in turn. Fish feed on the zooplankton and the process continues up the ladder of life.
Although the exact mechanisms by which they’re adapting aren’t well understood, it’s perhaps not surprising these animals are so flexible in the face of climate change.
As Ramp explains it, in order for phytoplankton to set off this chain of events, sunlight must first reach the exposed waters of the Gulf. This can only happen when the layer of winter ice blanketing the Gulf melts each spring. As a direct result of climate change, this layer of ice is disappearing much earlier than it did historically, forcing the entire Gulf into a premature bloom. Fin and humpback whales are now rushing north early, lest they miss the buffet.
Ramp said the Gulf has warmed approximately 2°C in recent decades, sparking this unfortunate trend.
“These animals, in the North Atlantic at least, have shown a huge resilience and have been really good to adapt,” said Ramp.
Although the exact mechanisms by which they’re adapting aren’t well understood, it’s perhaps not surprising these animals are so flexible in the face of climate change. They’ve been swimming the North Atlantic Ocean for millions of years, Ramp points out, even through the last ice age, during which the St Lawrence Gulf was covered in ice year-round. They have survived sudden changes in climate before, although past climate changes have been localized, said Ramp. Modern climate change is global, affecting the full range of their migrations.
“They have been very successful adapting to past climatic changes, which is of course a help to them now,” said Ramp. “The question is, how far can they push it?”
Unfortunately, climate change isn’t the only environmental pressure we’ve imposed on these animals. Ramp makes special note of underwater noise pollution, water contamination and competition with Atlantic Canadian fisheries for fish and krill. In addition to these threats, whales in the Gulf have consistently fallen victim to collisions with heavy ship traffic and entanglement in abandoned fishing gear. Ramp said these factors, combined with the persisting threat of climate change, could have dire consequences for these two species in the near future.
Fin whales are a pelagic species, meaning they roam the open ocean rather than hug the coast of any particular continent. This makes them difficult to study, but they have proven themselves a hardy species in other regions of the world, said Ramp. For example, fins in the Mediterranean Sea (north Africa) and the Sea of Cortez (California) stay there year-round, forsaking the north-south migration common among other species of whale. This flexibility in their migrations, combined with they’re capacity to cover huge distances, could make them more resilient in the face of climate change.
That being said, MICS has estimated there are only 330 fin whales still visiting the Gulf of St Lawrence and their population, once devastated by whaling, has yet to fully recover. Moreover, dozens of these fin whales have been reported dead in recent years and they are listed as a “species of special concern” under the Species At Risk Act (SARA),
“We’re worried the population actually isn’t doing that well,” said Ramp.
Humpbacks, on the other hand, have made encouraging strides toward recovery in Atlantic Canada, losing their “special concern” status in 2003. However, as a species heavily dependent on their north-south seasonal migration, the trend discovered by MICS could take its toll on these whales, as they’re forced to travel farther and farther north in pursuit of their retreating prey.
“[This study is] another indication of a fast changing environment,” said Ramp. “It’s amazing how these whales have so far been able to adapt, but there are limits.”
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