Study Shines Light on Noise and Whale Songs

For decades, humans have been enchanted with the songs of the humpback whale. First recorded in the 1960s, these songs have long captured our imagination and were even central to mobilizing support for the ‘Save the Whales’ Movement throughout the ‘60s and ‘70s.

Despite our fascination with humpback’s and their songs, however, there remain many unanswered questions as to why these whales are so musically inclined.

New research from scientists at Woods Hole Oceanographic Institute has provided some fresh insight into the world of whale songs. In a paper published this month in the journal Biology Letters, Aran Mooney and his team researched two components of whale songs: sound waves and particle velocity.

Unlike sound waves (the force that vibrates your ear drums), particle velocity (the physical vibration of a substance as sound moves through it) has yet to be studied thoroughly and is not fully understood. While researching off the coast of Maui, Mooney’s team discovered that particle velocity produced by whale songs—originally thought to travel a few meters at most—might travel much farther than originally thought.

Mooney found that they could measure vibrations from 200 meters away, but suspects that they could be felt as far as one kilometer away.

Humpback Whales Live in an Ocean of Increasing Noise

Previous research has shown that humpback whales could be potentially sensitive to particle vibrations in the water column. Unlike many marine mammals, humpbacks’ ear bones are fused to their skulls, which could allow for their jaws to act as giant, mammalian tuning forks, picking up particle velocity produced by other humpbacks, and potentially humans.

The humpback whale’s hearing evolved over millions of years in an ocean environment wholly different from the one we are now witnessing.

Today, a host of altogether new and alien sounds ring throughout the ocean. Offshore oil and gas explorations use literally earth-shaking blasts fired from airguns dragged along the surface. The blasts are powerful enough to penetrate the planet’s crust and bounce back to the surface, releasing the signatures of pockets of hydrocarbons from deep within the rock.

You need not be exploring for oil and gas to be adding to the sonic landscape of the oceans, however. According to Jesse Ausubel, the director of the Human Environment program at the Rockefeller University, “A cargo ship is basically a large rock concert passing by.”

And humpback whales don’t seem to show any affinity for this human-made noise. There is evidence to suggest that humpbacks respond negatively to anthropogenic sound, often ending their songs or even changing their songs’ frequencies in order to be heard over the unending and ever-increasing industrial drone.

With new shipping, mining, and construction ventures happening all the time, and ocean noise doubling every two decades, Mooney and his team’s findings could spell more problems for humpback whales. Most human-made noise in the ocean is low frequency, which contributes to low frequency particle motion. From Mooney’s research, it seems humpbacks could be especially sensitive to this noise. While we humans may not be able to hear well underwater, these sounds could come as relevant communication signals for humpbacks and other marine mammals.

A Call for Ocean Planning

Looking forward, a growing understanding of humpbacks, their songs, and their hearing capacity will continue to inform how we interact with these mammals, but also how we should protect them.

Though Mooney’s study took place off the coast of Maui, it has many implications for our dealings with humpback whales here in New England. Every year, humpbacks migrate mammoth distances, passing through our coastal waters in the spring and fall months, as they move between their tropical breeding grounds and their polar feeding grounds.

For us to be informed and prepared enough to accommodate these whales, it will be essential to look toward ocean planning and its potential for informing our relationship to the ocean. One component of the Northeast Ocean Plan is its data portal, which will include data and findings about marine mammals that’s accessible to everyone, and will be especially key for those in decision-making roles.

In New England, ocean planning continues to be of utmost importance and we hope decision makers will continue to rely on it in order to protect humpbacks and other marine animals traveling along our shores. The recent submission of the Northeast Ocean Plan marked a serious step forward in how we relate to our ocean resources and it will certainly prove invaluable as we look to protect our neighborhood humpbacks.

 

Seamounts Species Spotlight: North Atlantic Right Whale

The New England Coral Canyons and Seamounts are a special area 150 miles off the coast of Cape Cod. The unique geological formations make this area a biological hotspot, attracting many unique species. This blog post is part 2 in a series that profiles some of these incredible animals.

A rare sight in the open ocean, the North Atlantic right whale depends on the New England Coral Canyons and Seamounts area as a rich feeding zone each year beginning in early spring and lasting through the end of August.

A right whale is easily distinguishable from other species by its large head, two blow holes, and bumpy patches that dot its head and jawline. These rough patches of skin, called callosities, are frequently covered in microscopic sea lice which makes them appear white or orange. Each whale has a different callosities pattern, making individuals easily distinguishable from one another.

These massive critters can grow up to 50 feet in length and weigh in at more than 70 tons by consuming hundreds of pounds of zooplankton and copepods each day, making them one of the largest baleen whale species. Right whales feed using the same method as all baleen whales: by taking in a huge mouthful of water and then pushing the water through its tooth-like baleen plates to catch tiny organisms.

The canyons and seamounts make for a reliable feeding area for the right whale, with high concentrations of food sources, and relatively few human disturbances (most of the canyons and seamounts don’t see much commercial fishing activity).

Despite their impressive size, right whales are very slow and were historically an easy and popular target for human hunters for centuries. Currently, the North Atlantic right whale is listed as endangered on the ICUN Red List of Threatened Species.

What’s in a Name?

Back during the heyday of whaling, this graceful creature was the “right” target for a whaler’s harpoon because of its high blubber content and tendency to float on the surface once killed. This is largely thought to be what first caused the population to crash.

Although the species has been internationally protected since 1949 by the International Convention for the Regulation of Whaling, the global population is estimated to be hovering between just 300-500 individuals. These low numbers may be in part due to small litter sizes, making it more difficult for populations to rebound – or because of continued accidental human interference in a variety of ways: Just this spring, a baby right whale died after an apparent ship strike near Cape Cod.

Reducing Human Threats

Right whales can frequently find themselves sharing the waters with boats, resulting in seriously harmful or fatal collisions. Off the coast of New England, the Stellwagen Bank National Marine Sanctuary has been successful in moving shipping lanes to reduce the risk of commercial vessel strikes; a small 12 degree shift has the potential to reduce strikes by 58 percent. There has also been progress developing technologies to track whale activity that boats can use to help avoid collisions.

In other cases, development projects can pose threats, such as the Deepwater Wind offshore wind farm off Block Island. Deepwater Wind successfully worked with Conservation Law Foundation and other organizations, however, to halt pre-construction activities during times when right whales were known to be in the area.

Another significant threat to the right whale is fishing rope entanglement, which causes lacerations and infections and can make it difficult for the whale to dive and resurface. But, not all hope is lost: recent innovations in fishing rope production hope to minimize rope entanglement threats.

And, NOAA recently moved to significantly expand critical habitat for right whales, meaning federal agencies conducting permitting activities must work with NOAA Fisheries to avoid or reduce impacts on the critical habitat areas.

These actions are hugely helpful for this struggling species, but more will be needed to ensure population recovery. Comprehensive protection of feeding grounds, such as the canyons and seamounts, would be another big step in the right direction. With little fishing activity occurring in these areas, the canyons and seamounts are a relatively safe place for whales to live and eat, away from busier places where threats are higher.