RESEARCH PROJECT OCEAN SOUNDS
Vocal repertoire of killer whales (Orcinus orca) and long finned pilot whales in Norwegian coastal waters
Killer whales and long finned pilot whales are highly vocal and rely on a variety of different sounds for underwater communication and navigation. Both species, live in matrilineal groups and at least killer whales use group-specific dialects that reflect maternal relatedness, to avoid inbreeding and enhance group cohesion. North Atlantic killer whales live in matrilineal groups and mostly feed on herring. They use a special form of foraging called carousel feeding, during which they vocalize frequently, perhaps indicating the importance of calls for the coordination of group movements. During the last 16 years human activities around killer whales have been increasing steadily, both by the whale watching and fishery industries. Due to the increase in herring fisheries, killer whales started to feed from discarded fish from fishing boats purse seining for herring. This newly learned foraging behavior was transmitted rapidly and interaction with fishing boats is now common for most killer whale groups. Our goal is to understand the vocal behavior of the whales during different behavioral contexts. We will investigate vocal and airborne behaviors. This includes advanced analysis of the calls’ structure and usage of calls.
We have established a more comprehensive call repertoire catalog, which will be used as prerequisite for a long-term study of the vocal behavior in different contexts and in comparisons of different populations. Our results complement photo-ID and genetic studies. They reveal the identity of groups of whales, even under low light conditions such as the Arctic winter.
Killer Whales or Orca (Orcinus orca) in Norway:
Part of the Norwegian spring-spawning herring (ca 9 Million tons) migrates every year closer to the coast of northern Norway to spend the winter. In January they travel further south to their spawning grounds along the Norwegian coast. They spend the rest of the year in the open sea and return to northern Norwegian coast the following fall. Killer whales mainly feed on this herring stock and follow them all year round. The seasonal migration pattern of herring is known to go through major changes. The wintering grounds were in offshore waters in the Norwegian Sea until the late 1960’s. Following a collapse in the herring stock due to over fishing, the wintering grounds moved into the fjord system in northern Norway. Current research on the Norwegian spring-spawning stock of herring show that the wintering grounds are changing again, and it is possible that the herring will abandon the fjords in the coming years.
Toothed whale, largest dolphin, distributed all over the world, total numbers unknown.
Age: Females 50 yrs (max. 80-90 yrs); males 30 yrs (max. 50-60 yrs)
Size: Fully grown after 20-25 yrs: females 5.8m (max. 7.9m), back fin 0.8m; males: 6.6m (max. 9.1m), back fin 1.5m.
Weight: Male 4-5.000 kg, female 2.5-3.000 kg
Sexual maturity: 8-17 yrs. when 5.5-6.1m long (females 15 yrs, males 15-20 yrs)
Reproduction: One calf every 3-4 years, pregnancy lasts ca. 16-17 months with an arrested development from July-September. Birth can happen all year, but there is a peak in late fall/early winter. A female gives birth to 4-6 calves over a period of 25 years until ca. 40 yrs old. After reproduction, females live for another 10-20 years, probably to take care of their offspring and group. Newborn killer whales are 1.8–2.2 m long and weigh ca. 180 kg. The mother gives milk to the young for more than 1 year.
Group formation: Killer whales have very strong social bonds. The young of both sexes never leave their mother and live in small family groups together all their lives. This way the males in a group are not the fathers of the young but the brothers, cousins or uncles.
Smallest group consists of 6-15 animals, a matrilineal group, which consist of a mother and her offspring (both gender).
Clan: Matrilineal groups with similar vocal dialects and members that are related to each other.
Community: Several groups that have been observed together at least once. Members of different communities seem not to travel with each other and do not interbreed (e.g. southern and northern resident whales in British Columbia, Canada).
Travelling: Whales moving with all animals in the group facing the same direction, either in a line or in groups.
Feeding: Killer whales have a variety of prey (from fish to marine mammals) and seem to specialize if nutritious prey is available. In Norway, killer whales feed mostly on herring, but they also feed on salmon, mackerel, birds and seals.
However, there are different reported strategies to capture herring:
1) Carousel feeding: Whales herd herring into tight ball close to surface and stun them with tail slaps. Fish jumping and scales, pieces of fish and stunned herring can be observed on the surface.
2) Subsurface feeding: whales swim back and forth in a limited area, activity of animals on surface, such as porpoising and tail slaps (also in mackerel feeding).
3) Travel feeding: During traveling in a line in loose formations, they stop occasionally to feed individually.
4) Seine fishing feeding: Killer whales also follow fishing boats seining for herring and feed on the discarded fish of these operations. This behavior occurred and increased during the last years, due to an increase in herring catch quotas and fishing vessels.
Socializing: Whales are engaged in variety of physical interactions and aerial behaviors such as breaching, spy hopping, headstands, lob tailing and flipper slaps. Rolling around, chasing each other, and sexual behaviour.
Example of prosocial behavior: “Stumpy” has been taken care of several different matrilines in her 17 yrs of life!
Resting: Whales float motionless at the surface for a few minutes, or swim slowly in tight groups, diving and surfacing in a regular pattern. Resting whales should be left alone.
Killer Whales depend on vocal communication for social interactions, navigation and food location, and therefore produce a variety of sounds:
Clicks are predominantly used for echolocation
Whistles occur when whales are in close proximity to each other and stereotyped whistles may be important for close range coordination and maintaining interactions
Calls are used for both close and distant range communication. Calls are stereotypical pulsed sounds that are often characterized by two independently modulated frequency components:
A low frequency component (LFC) that has most of its sound energy below 10 kHz, and an upper-frequency component (UFC), which consists of a fundamental frequency ranging from 2 to 12 kHz with sidebands ranging to 100 kHz.
They also produce buzzes and squeaks in the mid frequency range, which often accompany calls.
It is a wonderful experience to go out to sea and watch killer whales in their natural habitat. There are many whale watching opportunities, but we should be aware that we may disturb the whales. To minimize disturbance and avoid harassing the whales we have to be aware of the whale’s activity. Whales should be approached carefully in swimming direction and sudden changes of speed or direction should be avoided. Signs of disturbance include whales diving every time the boat approaches, whales changing direction continuously or whales forming a tight group and swimming away from the boat. Special caution has to be applied when whales are feeding. Whales depend on acoustic communication and boat noise may interfere with their calls. Also, boats coming too close may chase away the herring and the whole feeding is disturbed. Therefore the best solution is to choose a responsible company / skipper with a long experience with whale safaris.
When swimming with the whales, let the animals decide to come to you and never swim into the middle of any kind of activity of the whales, especially feeding.
You will disturb the feeding process and they might not be pleased!
Just remember it is up to the whales to decide whether they want to interact with us. We cannot trigger or force them to come to the boat. But they do, sometimes, come very close….
Since we are guests out at Sea, we should not forget: NO garbage into the Sea, that includes any kind of cigarette filters! They never degrade and pollute the water!
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