Are Endangered Fin Whales Bouncing Back After Decades of Commercial Whaling?

The fin whale is currently listed as endangered under the United States Endangered Species Act and was moved from endangered to vulnerable status by the International Union for Conservation of Nature (IUCN) in 2018. The second-largest species of whale on Earth (after the blue whale), fin whales are also protected under CITES Appendix I and under the Marine Mammal Protection Act throughout their range.

Distinguishable by the ridge along their backs and two-toned lower jaws, fin whales were hunted relentlessly by commercial whalers throughout the mid-1900s—contributing to almost 725,000 deaths in the Southern Hemisphere alone before the industry was mostly eradicated in the 1970s and 1980s.

Despite an estimated 100,000 individuals alive today, the IUCN maintains that the global population of fin whales is increasing, mainly thanks to the reduction in commercial whaling. Projections indicate that the species’ total population has likely recovered to more than 30% of the levels from three generations ago.

Threats 

While whaling is no longer considered as large a threat for fin whales these days (the species is still hunted in Greenland, although with strict quotas managed by the International Whaling Commission), they’re still vulnerable to other factors like vessel strikes, entanglement in fishing gear, noise pollution, and climate change.

Fin whales require a large amount of small prey species to survive, which they strain from the water through baleen plates. A single whale can eat over 4,400 pounds of krill each day. For this reason, a threat to fin whale prey due to environmental changes and overfishing is also an indirect threat to fin whales themselves.

Vessel Strikes

Because of their large size and the overlap between migration patterns and vessel transit areas, fin whales are one of the most commonly recorded species reported in ship strikes. Since many of the strikes involving large vessels can be difficult to detect (or aren’t reported), it is hard to assess the actual number of fin whale deaths or injuries connected to collisions.

That said, scientists are able to make close estimates based on specific shipping lanes that intersect with whale habitats. The shipping lanes in California’s Santa Barbara Channel, for example, have some of the highest predicted whale mortality from vessel strikes in the United States waters off the eastern Pacific. A predictive model in the journal Marine Conservation and Sustainability showed an estimate of 9.7 fin whales killed from ship strikes each year between 2012 and 2018 in Santa Barbara (13%–26% greater than previously estimated). 

Another study in 2017 found that fin whale mortality across U.S. West Coast waters is approximately twice that for blue and 2.4 times humpback whale mortality. Between 2006 and 2016, whale mortality was greatest along the coast of central and southern California, especially along shipping routes between the port of Long Beach/Los Angeles and the San Francisco Bay Area.

Noise Pollution

It isn’t just vessel collisions that impact fin whales, but the underwater noise that the ships make as well. Fin whales produce a variety of low-frequency sounds to communicate, some of which can be as loud as 196.9 dB—making them one of the loudest animals in the ocean. Increased underwater noise can negatively affect entire fin whale populations by altering their normal behavior, chasing them away from important breeding or feeding areas, and even causing stranding or death.

According to a study conducted by the Institute of Geophysics of the Czech Academy of Sciences in Prague and Oregon State University, we may have even more to lose when it comes to fin whales and noise pollution. Research published in 2021 revealed that measuring sound waves in fin whale songs could help determine the makeup and thickness of the Earth’s crust, helping scientists study undersea geology without having to rely on underwater seismic airguns—which are conventionally used to study Earth’s oceanic crust but can be expensive and not environmentally friendly. 

Fishing Gear Entanglement

When fin whales become entangled in fishing gillnets and other equipment, they may swim off with the gear and become fatigued, restricted from breeding and feeding, or injured under the weight. In more severe situations, they can become completely immobilized by the gear and either starve or drown.

Research shows that threats to these whales from fishing entanglements are much worse than previously thought. One study off Canada's Gulf of St. Lawrence (an important feeding ground for whales) found that at least 55% of the fin whales studied had scars on their bodies consistent with entanglement, suggesting that they had already been caught in fishing nets at some point in their lives.

Climate Change

Like all marine animals, the threat to fin whales from climate change and warming oceans is monumental, especially since whales get their cues for important behavior (like navigating and feeding) directly from their environment.

Altered ocean conditions and the timing or distribution of sea ice can also disconnect fin whales from their prey, leading to changes in foraging, stress, and even reduced reproduction rates.

In 2015, the NOAA revealed an unusual mortality event that resulted in the deaths of 30 large whales in the Gulf of Alaska—one of the largest strandings ever recorded in the region; the mortality event included 11 fin whales. At the time, the NOAA suggested that warmer ocean temperatures and a resulting record-breaking toxic algae bloom were likely the cause behind the tragedy.  

What We Can Do

One of the best ways to access conservation measures within the global fin whale population is by determining the actual number of whales in each subpopulation and monitoring how the stock is fluctuating over time.

The NOAA Fisheries division prepares annual stock assessment reports for all marine mammals in U.S. waters by territory in order to evaluate the overall health of global populations, discover vulnerable areas, and establish the best course of action to take for each species.

Expanding speed limits for large ships in certain areas could decrease vessel strikes, as well. The same study in Marine Conservation and Sustainability concluded that, if 95% of vessels larger than 300 tons traveling in the Santa Barbara Channel shipping routes implemented voluntary vessel speed reductions requested by the NOAA, it could reduce whale vessel strike mortalities by 21-29%. Although most of these speed limits are voluntary, some regions could consider mandatory speed reductions if the desired levels of cooperation can’t be met.

Living at the top of their food chains, fin whales play an extremely important role in the overall health and balance of our planet’s marine environment. The good news is that these impressive animals have already demonstrated their ability to bounce back after relentless whaling threatened to wipe them out altogether, indicating just how strong the species can be when supported by conservation.