With no cruise ships, humpback whales have different things to say
On the evening of March 13, 2020, Michelle Fournet was preparing for confinement like so many others. Yet, as she tidied up her office at Cornell University in Ithaca, New York, she realized that the impending quarantine might offer her a once-in-a-lifetime chance. An expert in communicating with marine mammals, particularly humpback whales in the busy Glacier Bay National Park in Alaska, Fournet found that the sudden shutdown of the Alaskan cruise industry made it possible to see how whales at bump vocalize in a sea without those big ships. Locked in New York, she jostled her colleagues in Alaska to sink a hydrophone in the same place where she had recorded whales in the summer of 2019.
Fournet spent the winter and spring listening to the hydrophone recordings and comparing them to those of the previous year. Analysis shows that even in the absence of cruise ships, humpback whales made roughly the same number of stopovers. But her initial data, which has yet to be released, shows a key change: Humpback whales made a certain type of call, which she calls a whup, much less often.
In the summer of 2019, around 66% of humpback whale calls were whups. In 2020, when median sound levels were three times lower, the frequency of whale hissing fell to less than 50%.
Fournet also compared his call count to recordings of humpback whales made in 1976 by researcher Roger Payne, who was studying whales in the nearby Frederick Sound area. The proportions of whups in this 45-year-old recording, which was made in the absence of boats, Fournet says, are very similar to his recordings made in 2020.
Fournet’s discovery is among the first results of studies taking advantage of the so-called anthropause – a name coined for slowing or suddenly stopping human activity around the world due to COVID-19 blockages – which allude to the more subtle impacts of noise pollution on marine life.
For the most part, researchers aren’t sure what each type of humpback whale vocalization actually means. Based on his earlier work, however, Fournet believes that for the humpback whales of Glacier Bay, whups are kind of a contact call. “It’s a way of announcing their presence,” says Fournet. This can help them keep their spacing when feeding on capelin, sand lance, and other fish.
If this interpretation is correct, the prevalence of whups in non-pandemic weather suggests that noise from cruise ships may affect the table manners of humpback whales.
Scientists know that noise pollution can make it harder for marine animals to hear, find food, and navigate, and can lead to hearing damage as well. But Fournet says they’re just starting to look at the more subtle impacts, such as how a change in the proportion of calls might affect the quality of interactions.
Paul Spong and Helena Symonds, who run OrcaLab, a whale research station off the east coast of Vancouver Island in British Columbia, where cruise ships pass from Seattle, Washington, to Glacier Bay, have saw a less pronounced anthropause, with boat traffic and other persistent noise makers. But they got respite from the cruise ships, says Spong, who can drown everything else for an hour by the way. With none in the water, he said, “It was just beautiful to listen [the whales]. “
Spong and Symonds did not link the specific vocalizations of humpback whales to specific meanings in British Columbia. However, Symonds says OrcaLab is one of many research centers that installed a coordinated network of new hydrophones along the coast of British Columbia in 2020. Thus, with the resumption of vessel activity from cruise, they will be able to compare their 2020 ambient noise recordings. , industry and whales in the post-pandemic years. “I think any noise in the ocean, especially loud noises, disturbs behavior,” Spong said.
However, even though researchers can show marked changes in the vocalizations of humpback whales to ship noise, it is difficult to link this data to social impacts. Jackie Hildering, co-founder of the Marine Education and Research Society in Port McNeill, B.C., explains one reason why: The meanings of calls can vary depending on what the whale is doing, where it is and, most importantly, who the fact.
“People do different things in different places,” says Hildering. A broader cultural context, such as whale identities, relationships or migratory routes, is needed to understand any given call or the implications of changes in those calls triggered by noise pollution.
Fournet is now working to identify the social context of vocalizations made by whales in Glacier Bay. She correlates her hydrophone recordings with observations, made by her colleague Christine Gabriele of the US National Park Service, of what whales did when they made a given sound.
Fournet hopes that by further quantifying these changes, the data will reveal not only how whales vocalized differently during anthropause in the unique Glacier Bay theater, but also what they were saying.