One of Whale Wise's key projects is to find out how humpback whales may change their behavior in response to whale-watching vessels, particularly in Skjálfandi Bay. One way they might react is acoustically, changing their calling behavior, since whale-watching vessels make sounds underwater that can be heard by the whales. Discovering if whales do actually change their calls due to whale-watching vessels, is usually difficult to answer, due to a lack of comparable time without whale-watching (in science this comparable time is called a control). You could compare the calling behavior of the whales during whale-watching with nighttime, winter, or times when there is a storm, and no whale-watching is happening. However, one must consider that the whales might just call differently because their behavior could be different at night, or in winter. And storms themselves make a lot of noise, so these occasions are still not truly comparable to periods in which whale-watching would occur.
However, Whale Wise recently had the opportunity to have a suitable control: during the Covid-19 pandemic the vessel traffic was reduced drastically, and they used this time to find out how the whales react to the vessel noise. They deployed a hydrophone (underwater recording device) during the pandemic in 2020 and used recordings of 2018 as a non-pandemic comparison.