Is boat noise effecting humpbacks?

UCD animal behaviorist Brenda McCowan and graduate student Sean Hanser are studying the vocalisations of humpback whales off the coast of Alaska. A large bubble made from a steady stream of air exiting the blowhole of a massive humpback whale surrounds and traps a school of herring, while another humpback bellows a "feed call," herding the other members of the group for dinner.

This cooperative feeding behavior, called bubble netting, occurs in a subset of humpback whales off the coast of Alaska, and is just one of the communication behaviours researched.

Humpback whales, an endangered species, produce a "whole slew of noises," and have one of the most diverse repertoires of vocal communication in the animal kingdom. They produce a variety of sounds in Alaska, where they feed and socialize, and they produce songs in Hawaii during their mating season. McCowan and Hanser,are researching humpback whale vocalisations and looking specifically at the effects of boat noises in southeast Alaskan waters on their complex interactive vocal behaviors.

With a variety of noises from what sounds like an elephant to barking dogs, humpback whales along with other marine mammals have been recorded for the sound effects in movies like Jurassic Park. "Humpback whales make many sounds that remind you of other animals," Hanser said.

Singing in Hawaii is well documented and understood, but scientists know little about the other noises made by humpbacks. One of the projects is to understand the breadth of humpback whale vocalisations. They study the many recordings they collect to figure out how many vocalizations are made over time, how often they are made and how they are made in relation to other vocalizations. Researchers will also experience humpback vocal communication from a whale's perspective by placing microphones on a few whales.

One specific focus of their research is on the "feed call," a stereotypic sound that is flat and tonal, and is similar to "an opera singer with a vowel. This call is thought to either attract prey, herd other whales in the group around the prey or possibly both. They are studying how these calls can be disrupted by certain kinds of boat noises and certain kinds of frequencies. These noises may interfere with the whale calls and cause the humpbacks to alter their behavior. They compare recordings of whale sounds in the presence and absence of boat noise.

Research on the effects of noise on whales is a fairly recent endeavor that has primarily taken place in the last decade,a lot of people are concerned with the effects of large sounds from naval sonar and other large vessels. Sonar from three to four miles away can burst a whale's eardrums, causing them to bleed.

However, McCowan and Hanser's research looks into the effects of more subtle sounds made by small vessels and channel traffic, which can still change whale behavior and may prevent the success of an already endangered animal. The sounds of boats and ships, while small in comparison to sonar, can disrupt whale communication like a noisy phone line. Just as people have to change the way they speak to someone over the phone if the connection is bad, such as increasing the volume of their voice and using repetitive language, whales may also have to alter their vocal communication behavior.

McCowan hopes this study will continue for up to 10 years, if funding permits, so she and Hanser can also look for changes in the population over time. They also hope to observe effects of channel traffic on which areas these animals prefer to utilise. Another aspect of this study is to research vocal communication as a means of preventing deaths from entanglement in fishing gear. Recording noises while the whales are entangled enables researchers to acoustically detect the "sound of distress". While it is speculative right now, detecting these sounds may enable researchers to locate a trapped whale and disentangle it, preventing fatality.

source: californiaaggie.com