February 13, 2014
British Antarctic Survey Team Counts Whales Using Satellites
Brett Smith for redOrbit.com - Your Universe Online
A new report from the British Antarctic Survey has revealed that satellites can be used to accurately estimate whale populations. The report authors said the technique they developed could revolutionize the way whales are counted.
"This is a proof of concept study that proves whales can be identified and counted by satellite,” said study author Peter Fretwell, a researcher with the British Antarctic Survey.
“Whale populations have always been difficult to assess; traditional means of counting them are localized, expensive and lack accuracy,” he continued. “The ability to count whales automatically, over large areas in a cost effective way will be of great benefit to conservation efforts for this and potentially other whale species."
In the report, which was published in the open-access journal PLOS ONE, the researchers looked at one of the biggest right whale populations, which were mating off the coast of Argentina at the time. The population was chosen, due to its huge size and tendency to bask near the surface in large numbers around sheltered coastal oceans during mating season.
Nearly driven to extinction, these right whales are seeing a limited recovery following the conclusion of whaling activities by the international community. However, many recent deaths have been seen in their nursery waters off the coast of Argentina. Their population is currently unknown, but with this sharp increase in calf fatalities, conservationists have been calling for accurate population estimates.
To test the prospective of using high-resolution satellite imagery to find and count baleen whales, the study team used satellite imagery that covered 40 square miles and could penetrate farther into the water column than images off other satellites. The authors utilized four various automatic identification techniques and analyzed the results compared to those using manual whale detection methods.
The manual methods used three main criteria to identify a whale: objects visible in the image should be the right configuration, they should be where whales would be expected to be and there should be very few similar objects that might be mistaken as whales.
The manual counting revealed 55 probable whales, 23 possible whales and 13 sub-surface features. The automated counting method utilized light from the far blue end of the spectrum. This technique revealed 89 percent of probable whales identified in the manual count.
The study authors concluded that these techniques are more effective than traditional techniques of determining populations of marine mammals. They added that this is one of the first successful research studies to use satellite imagery to count whales, a technique that might be applied to future surveys of various marine mammal populations.
"Whales populations have always been difficult to assess, traditional means of counting them are localized, expensive and lack accuracy,” Fretwell said. “The ability to count whales automatically, over large areas in a cost effective way will be of great benefit to conservation efforts for this and potentially other whale species."
The researchers noted that future satellites will provide even higher quality imagery and allow for greater confidence in not only finding whales – but also differentiating mother and calf pairs.
Image Below: This is a satellite versus aerial view of southern right whales. Credit: British Antarctic Survey