The Ocean Alliance conducts aerial surveys in Patagonia, Argentina
and photographs Southern Right Whales in order to identify individuals from
the callosite patterns on their heads.
Photo: Iain Kerr
April 28, 2002
This is Genevieve Johnson speaking to you from Western Australia.
One of the most satisfying components of our five-year global expedition in search of sperm whales, is the opportunity to meet with other whale researchers from different parts of the world and to hear about the work they are doing.
While in Fremantle, we met with Chris Burton,
Director of the Western Whale Research Institute here in Australia.
Whereas we make most of our observations from a boat, Chris does most of his
data collection from an airplane. He flies monthly aerial surveys over south-western Australia in search of the elusive Blue whale. Aerial surveys are popular with researchers because they allow them to cover large areas of ocean in relatively short periods of time. Even though observers in a plane flying over a herd of whales will see about half the number of whales that observers on a boat steaming through the same population will see, the plane can cover between 10 and 100 times as large an area in the same amount of time. In addition, on calm days, planes afford one of the best vantage points from which to view whales because the entire animal is visible and can be photographed clearly. When whales are in very shallow water (not common in sperm whales, but very common in right whales) they cannot get out of sight of a plane and the aerial view becomes the best way to watch several animals interacting at once.
Today Chris discussed his work with us.
My name is Chris Burton, I've been doing whale related research since 1985 on the west coast.
With aerial surveys, we attempt to look at the broad distribution of Blue whales over a certain area. The aircraft are normally twin engine with a high wing, we have two observers and a pilot and we work out a track line with a number of waypoints. We have to fly a fair way off the coast; normally about 50 - 60 miles and we do these surveys once a month. Initially our project was to look at the whale aggregation off Rottnest Island that is west of Perth. We have been doing flights once a month for three years, flying the same transect and counting the number of whales. We measure the angle of the whale from the aircraft so we can work out the distance from the track line, how many there are, whether there are females and calves, giving us a picture of their seasonal distribution off the coast. This work is done in conjunction with other researchers; Curt and Micheline Jenner do the boat-based work in order to get close to individual whales to take photographs and to take skin samples for genetic analysis.
Chris Burton conducts aerial surveys over south western Australia looking
for Blue Whales to attempt to find out more about their
distribution and abundance.
Photo: Chris Johnson
Blue whales were hunted here along the west coast, the Russians came by in the mid 60's and took quite a few hundred of these animals. That led to an initial research program run by the International Whaling Commission (IWC) and participating scientists going out on a number of ships, two of which actually left out of Fremantle in December of 95 and 96 to try and find Blue whales off the west coast and down in the Southern Ocean. One of the ships that left Fremantle found whales the next day off Rottnest Island. The researchers stayed there for two weeks, taking photo identification and samples, this led on to the particular project under way now.
We want to find out how long the Blue whales are here and whether they are here in winter. We take photos to look at individuals and compare them with other databases of Blue whales in the southern part of Australia and maybe even other countries. We don't know whether these whales go to Madagascar for example or down to the Southern Ocean or across to Portland where we know there is another group. We also record calls for other researchers who are doing acoustic monitoring to see whether they match the core structure of other populations. We have a lot to find out, we really just don't know.
When we are out there flying transects, we record all marine mammal sightings and note if we can identify the species. It is very difficult to identify individuals from the height we fly which is at 1500 feet at 120 knots. We've seen Humpbacks, we've actually seen a sperm whale and a lot of dolphins. We also note oceanographic conditions, for example there is a lot of surface algae out in summer and we have noted that Blue whales may be feeding out there on krill swarms, but we think it's sub-surface.
We don't know how far these animals are distributed along the coast. Last year there was some aerial surveys flown off the north coast, off Exmouth and there were some Blue whales found off there. I have also been working with whale watchers down south off Geographe Bay and every year like clockwork, around September, October and November, Blue whales just appear like clockwork. We don't know if those animals are the same as the ones we see off here.
The largest number we have seen in a single flight was in February 91, when we saw 13 animals. Normally it's 1or 2 animals or even up to 4 or 5, that's generally from November to May. We haven't seen any during the winter months of the west coast.
Some species of whale, like this Humpback, cannot be identified
from the air. Instead photographs must be taken in a boat where
individuals are indentified by the patterns on their tails.
Photo: Chris Burton
The aerial surveys are a really good method of determining the overall distribution of Blue whales in an area, the density as well as seasonal changes over the years, as long as you do it consistently over a reasonably long time period. You need to do boat based work to get close enough to do photographic work to identify individuals, but you can't do this from a plane with Blue whales. They do have patterns, but it would be very difficult to get good images from the air because they are so subtle. You really need to get high-resolution images of their flanks and tails from the water. With other whales like Southern Rights, they have a pattern on the top of their heads, which are ideal for aerial photography. If you want to identify individuals in most other species, you really need to do boat based work and look at their tail up dives and flanks and then compare them with other data bases. But with the Blue's we just use the aerial surveys to get an idea of their distribution in a certain area.
Everyone on board the Odyssey wants to participate in an aerial survey in the future. We also hope that as we make our way across the Indian Ocean, we will be able to get some help in locating sperm whales whenever we are near enough to land for a plane to come search for us. So stay tuned.
Log by Genevieve Johnson