Top predators are exemplars of how little we know about the environment. It’s staggering to imagine how far we’ve progressed in our understanding of these cognitively complex, ecologically diverse, charismatic creatures.

Top predators are exemplars of how little we know about the environment. It’s staggering to imagine how far we’ve progressed in our understanding of these cognitively complex, ecologically diverse, charismatic creatures.

Tigers, lions, orcas and many other predators are known as apex predators or alpha predators or apical predators. These predators residing at the top of a food chain upon which no other creatures prey. The apex predator concept is commonly applied in wildlife management and conservation. Killer whales or orcas are the best example of apex predators.

The Tehran Times had an interview with Robert L. Pitman as a marine ecologist who has been studying seabirds and cetaceans since 1976. His main interest is Antarctic killer whale ecology and systematics. He describes some of the most significant findings and provides recent updates on what it is we know and don’t know about these fascinating animals.

Q: Could you explain about the photographs that researchers took from Antarctic and ocean waters to describe different morphological types of orcas?

A: Photography is an important part of killer whale research. We take a lot of our own photographs but we also rely on photos taken by other people, including other researchers and tourists. Photographs are crucial for a number of reasons. Once we identify what we think might be a different type (or possibly species) of killer whale, based mainly on how they look and what they feed on, we can use photos to test our ideas. For example, if two different-looking types occur in the same area and we don’t see any intermingling of types or find any intermediate-looking forms, then we have evidence that they probably do not interbreed and they could be different species. We also use these photographs for mapping the distributions of the different types of killer whales to learn about differences in their habitat use.

Q: Why body measuring is important? Please point out some burgeon technologies in this field?

A: We are still trying to sort out how many different species of killer whales there might be and how we can tell them apart. Differences in body measurements and proportions can be important for recognizing and identifying different types or species of animals. Because killer whales are so big, we can’t catch them and measure them – we have to work with live animals in the field, and for that we have two main methods.

In certain circumstances we can fly over them with manned or unmanned helicopters and photograph them from the air; if we know the exact height of the aircraft when we take the photos we can measure their lengths and proportions directly from the photos. Another method that we use from a small boat is to have a pair of lasers mounted on a handheld camera, which projects two green dots spaced exactly 10 cm apart onto the dorsal fin of the killer whales. From the photos, we can then measure the size of the dorsal fin and also the dorsal-fin-to-blowhole length.

From that last measurement we can estimate total length. We know from these measurements that some types of killer whales measure only 6 m in length while others range up to almost 10 m; size differences this large probably means that it is probably physically impossible for these killer whales to interbreed.

Q: Would you please tell me more about your experience to refined focal groups of orcas in Antarctic by satellite tags?

A: To study movements and diving behavior of individual killer whales, we use a crossbow to attach a 40 g satellite tag to their dorsal fin. The tags have two, 70 mm barbs that penetrate harmlessly into the fin and remain attached usually for 2-4 months before the tag falls off. While the tag is transmitting, we can track the whale on our computers from anywhere in the world. From this we have learned for the first time that Antarctic killer whales can dive to over 700 m and they migrate 1000s of km to the tropics at least once a year. Why they go to the tropics is a puzzle though, because they don’t spend any time there - they go, turn around and head straight back to Antarctica.

Q: What is the most reliable method to determine demographic changes especially in hot spots where orcas are threatened more?

A: Perhaps the only way to determine demographic changes in a long-lived species such as killer whales is to monitor large numbers of individual animals over long periods of time; and with killer whales we do that using photographs. With reasonably good photographs of their dorsal fins, every individual killer whale is recognizable, and over periods of decades. With a continuous photographic record we can determine at what age killer whales mature, when they first start to breed, how often and for how many years do they calve, and how long do they live. And because they are top predators, their populations are usually small – dozens to hundreds - which makes managing a photo catalog even easier.

Q: Are scientists close to solve the mystery of mass suicide among whales and especially orcas?

A: There are apparently different reasons for the mass stranding’s of whales and dolphins. For deep-diving species, high-energy noise in the ocean from seismic testing and military sonar apparently frightens animals that are deep in the water, causing them to surface too quickly, which can have dire physiological consequences, sometimes resulting in mass stranding. Killer whales on the other hand, rarely mass strand – we think that when they do it is because they live in matriarchal societies: groups are composed of an oldest female who is actually the group leader, and all of her offspring. If, after her 80-100 year lifespan, she becomes ill and wanders into shallow water, her group, which may have followed her lead for perhaps most of a century, might just follow her up on the beach when she dies. Just a guess.

Q: How could fishery managers help to scientists?

A: In the Pacific Northwest (US and Canada) people love their killer whales and have passed strict laws protecting them. But the fish-eating type there (“resident” killer whales) consume an enormous amount of salmon – their preferred prey. There is also an important salmon fishery in the area, so conflict was inevitable. Currently, the salmon and the killer whales are both endangered due to historically bad management of marine resources. People there need to decide if there will be any killer whales or salmon left for future people to enjoy, or if they are going to eliminate them all for short term gain. It is a familiar problem just about everywhere in the world.

Q: How could scientists measure PCB (Polychlorinated biphenyl) levels in orcas blubber? Are there any similar methods for measuring bioaccumulation in smaller mammals such as Caspian Seal (Pusa caspica)?

A: To measure pollutants in free-ranging killer whales, we use a crossbow to shoot a dart at them; the dart takes a small plug of skin and blubber, bounces off the whale’s back, and floats on the surface – then we take the sample back to the laboratory and analyze it. People have used similar methods for seals and sea lions, but you have to get quite close (20 m or so) for this to work. For animals that do not allow a close approach (Caspian seals) this method will not work, in which case you have to try to live-trap animals or work with stranded animals.

Q: In your opinion how much volunteer reports and public assistants could help to gather wealth information and even protect of endangered species?

A: In Antarctica, tourists on cruise ships have donated thousands of killer whale photographs for our project; the photographs will be used to estimate population sizes of the different types of killer whales, and learn more about their movements and prey preferences. And there are other opportunities for “citizen science” participation: I recently revised distribution map of killer whales for the IUCN (International Union for the Conservation of Nature). Many of the records I used were from YouTube and the internet – sometimes people out for a day on the water saw some killer whales and posted photos of them. An invaluable resource!

Q: How environmental disasters such as oil spill can threaten the population of orcas?

I think the biggest current threat to killer whales is that we don’t know how many distinct populations, subspecies, or even species of killer whales there are. The current consensus is that there is one species found around the world, but recent molecular genetics analysis indicates that there might actually be several species. We can’t really assess threats to killer whales, including oil spills, until we know how distinct the populations are, where they occur and how large they are.

For its intelligence, size, power and beauty, this is the most spectacular animal on our planet. I always tell people if you get a chance to see one species of animal in your lifetime, you have to see killer whales in the wild! Also, I call them killer whales but orca is also correct.