If you live in or work a city, the chances are you spend at least some of your time commuting to work during rush hour.

But next time the stress of the traffic jam or queues for trains get to you, take a moment to appreciate that humans aren't the only animals put through the ordeal.

Sharks in the Pacific Ocean have a rush hour too, according to a new study.

At least seven species of sharks visit Palmyra, but the camera confirmed that smaller-sized sharks such as the ubiquitous blacktip variety (pictured) were the most common.

HOW THE SHARK HIGHWAY WAS FOUND The marine animal traffic was monitored for 443 hours during a month-long period. The acoustic camera made a total of 1,196 shark observations; the maximum number in a single frame was 10. Acoustic cameras use sonar technology or pulsed sound wavelengths to produce fast-frame, detailed imaging even in low-light, turbid environments. The results surpass the range capture and clarity capabilities of traditional optical cameras. With that data, the scientists were able to compare shark density and directionality of travel across four tidal periods. Advertisement

A research team from UC Santa Barbara studied the way sharks moved in Palmryra Atoll, by monitoring how they moved in and out of a lagoon, through a deep channel.

'Because there are big conservation issues with sharks, it was important for us to get a good report card or health chart started for the healthiest "patients" as well as the sickest,' said lead author Professor Douglas McCauley, from Department of Ecology, Evolution, and Marine Biology at UC Santa Barbara.

Palmyra Atoll is a 5 square mile (8 square kilometre) ring of coral half way between Hawaii and American Samoa. It is home to a variety of sharks, manta rays and turtles.

It turned out this channel is an important 'highway' for sharks, and the shark traffic peaks between 7 and 8PM.

'My research team and I have spent a lot of time on Palmyra around this particular feature, but it wasn't until we were able to light up that world and extract data that we discovered this huge rush hour of sharks in the evening,' said Professor McCauly.

'This matters. It's important to know for how we deal with sharks and to determine their behaviour patterns.'

The researchers used dual-frequency identification sonar, an acoustic camera originally designed for the US Navy by Sound Metrics Corp, to create a sound gate through which the sharks travelled.

The marine animal traffic was monitored for 443 hours during a month-long period.

Palmyra Atoll is a 5 square mile (8 square kilometre) ring of coral half way between Hawaii and American Samoa. It is home to a variety of sharks, manta rays and turtles

The marine animal traffic was monitored for 443 hours during a month-long period. It turned out this channel is an important 'highway' for sharks, and the shark traffic peaks between 7PM and 8PM

HOW SONAR WORKS The word sonar was originally an acronym for SOund Navigation And Ranging. Sonar is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise. Sonar detectors send out waves and wait for the signals to be reflected back. Dolphins and whales can tell the difference between objects as small as a BB pellet from 50 feet (15 meters) away. They use sonar much more than sight - to find their food, families, and direction. Advertisement

'We see this as being an important part of new technology coming online to better track the health of shark populations, better understand their behavior and help do a better job with their conservation,' said co-author Paul DeSalles, a researcher in McCauley's lab.

'Before, we had no way to quantify how often and which sharks were using this space. This study fills in those gaps.'

Acoustic cameras use sonar technology or pulsed sound wavelengths to produce fast-frame, detailed imaging even in low-light, turbid environments. The results surpass the range capture and clarity capabilities of traditional optical cameras.

The acoustic camera made a total of 1,196 shark observations; the maximum number in a single frame was 10.

With that data, the scientists were able to compare shark density and directionality of travel across four tidal periods.

The word sonar was originally an acronym for SOund Navigation And Ranging. Sonar is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise

At least seven species of sharks visit Palmyra, but the camera confirmed that smaller-sized sharks such as the ubiquitous blacktip variety were the most common.

'Through this study, we also were able to confirm that large sharks do indeed transit into Palmyra's lagoons,' DeSalles said.

'The data allowed us to get a quantitative understanding of size classes and when these big sharks are using the channel.'

In fact, the camera recorded a definitive transit of large numbers of sharks from the forereef into lagoons, which hasn't been directly observed at this site using other methods.

According to the researchers, such an observation may be of even greater value in contexts where sharks are rarer and use of alternative data collection methods is untenable.

'Sharks are in trouble worldwide, so we need to be thinking about new tools and new technologies for studying them, and this one, which wasn't designed for scientific applications, worked very well,' said Professor McCauly.