- Ocean Sounds Team
We are still thrilled from the unforgettable encounter we were lucky to be part of, during the last field work…Orcas! Precisely, a group of 9 orcas were traveling along the coastline.
That morning we decided to conduct an early morning boat fieldwork trip due to the weather conditions that were supposed to change in the afternoon, becoming more challenging for our collection data. Nerveless, it's well know how unpredictable doing research in marine mammals is, in fact our whole schedule changed thanks to an amazing encounter with a pod of killer whales. The pod included 9 individuals, of which two were mother and calf pairs traveling side by side laterally to the group that was led by a large male, that was easy to detected because of his huge dorsal fin, up to 2m in length. The very tall dorsal fin, characteristic on the male allows us to recognize the gender between the individuals in their adult stage, as female and young show a shorter and curved fin. Another hint is the body size, as male of killer whales can reach approximately 9m in length, in contrast with the female that can reach about 7m.
We kept our distance from the pod, respecting their space, driving the boat slowly. We saved the coordinates of this amazing sighting, took photo-IDs and recorded their behavior, monitoring them visually from the boat using the binoculars and above the water with the drone footages.
We confirmed that the pod was scanning, looking for food, as all the individuals were traveling parallel to each other and very close to the coastline. In fact, that morning there were many fishing boats out at sea looking for mackerel, and apparently, they were not the only one searching for it.
Some groups of Orcas occur in Norway almost all year-around and during the summertime these waters have many pelagic fish which are included in their diet. However, their diet can differ based on the distinctive groups of killer whales, varying from schooling fish, marine birds, or marine mammals.
When the pod slowed down, we were able to deploy the hydrophone, aiming to collect acoustic data that could match with our visual recording. We could not hear much at first, many boats were around masking the noise, also the pod was not vocalizing that much, only a few clicks, as they were still traveling. In fact, when whales are traveling or resting they don’t emit the same amount of vocalization like when they are hunting, feeding or socializing.
In the latter case, acoustic recordings are identified alongside several vocalizations and depending on the species observed with many clicks, calls and whistles. Orcas belong to the group of toothed whales, and as it usually the case of this group, they produce sounds at high frequency, using echolocation clicks for detecting the prey.
As the pod was moving in deeper waters, we retrieved the hydrophone on board and with the due distance, we headed in the same direction.
As you can imagine the whole Ocean Sounds team was super excited about the encounter we were attending. We properly coordinated our job, without missing any details of this sighting, filling up our notebook with behavioral data and taking as much photo-IDs as we could, hoping to find marks that could recognize the individuals of the group and eventually associated them with animals already identified in the catalogue.
The pod changed directions, moving away from the coastline and heading north into deeper waters. It was at that moment that the group started to separate, with the male heading alone, two individuals travelled in shallow waters and the others including both mother and calf pairs were in the open waters of Vestfjorden, difficult to keep our eyes on them. This separation could have been a hunting strategy, in fact, this species is well known for exhibiting some of the most impressive social hunting in the marine world. Only after a few more kilometers of driving north, there was high surface activity and many birds flying above the area, a characteristic scenario of a feeding behavior.
Working as a team, the orcas were jumping and using their tails and slapping to stun the fish. We stopped the engine and quickly deployed the hydrophone underwater and with any doubt we could confirm that they were feeding! Loud vocalization, distinctive clicks and whistles were heard from the headphone. It is useful to be able to associate their behavior spotted above the surface with their acoustic sounds underwater.
The behavior observed above the water line was very dynamic, it seemed like each individual was making their own part to collaborate during the feeding time. With adult animals spy hopping and tail slapping, the young calf showed itself off a few times, jumping above the surface multiple times. During this feast that lasted a while, we were able to collect many acoustic recordings, photo-IDs and videos of the individuals.
We realized they were done feeding as no more vocalization could be heard from our head phones and they started moving further north. It was then that we decided to call off the sighting, as the wind picked up, as expected, so we made our way back to the harbor.
It was just an unforgettable day, experiencing part of the routine of this magnificent species. Lot of material to work on for further understanding their behavior and adding scientific information about their biology and distribution.