Institute of Marine Research
Harbour porpoises are found along the entire coast of the North Atlantic from West Africa, northwards into Europe, west to Iceland, Greenland, and North America, as far south as North Carolina. In Norway, they range from the North Sea, northwards along the coast into the Barents Sea. It is thought that porpoises along the Norwegian coast consist of at least two populations, or stocks. One in southern Norway, and one in northern Norway, or the Barents Sea. Currently, genetic studies are being conducted to investigate this hypothesis, but there is little information on the movements of porpoises. Hence, it is unknown whether porpoises from the Barents Sea area remain there year round, or if they move southward and mix with the porpoises living in the more southern areas.
Varangerfjord is a large fjord, north of the arctic circle, in northeastern Norway near the Norwegian-Russian border. In this area, stationary, wedge shaped surface nets are set for salmon that are returning from the sea into the rivers to spawn. These nets are set close to shore to trap the salmon as they follow the coastline toward the rivers. There are also a large number of harbour porpoises inhabiting these waters due to high concentrations of their prey species, herring and capelin. Quite often, porpoises swim very close to shore as they hunt for their prey. Occasionally, harbour porpoises swim near the salmon nets and become entangled. If they are not removed, they will eventually drown.
The goals of this project are two-fold. Firstly, to rescue as many porpoises as possible from the salmon nets, and the second, to fit a few of the rescued porpoises with satellite tag transmitters in order to follow their movements. The project began in 1999, when researchers from the Institute of Marine Research (IMR) in Bergen, Norway, worked in co-operation with salmon fishermen from the Jarfjord region of Varangerfjord. During the first two weeks of June, a total of 8 porpoises were rescued from nets. Three of these porpoises (two males and one female) received satellite tags.
Researchers from the IMR travel several times daily with a small boat along a 22 km (13 miles) stretch of coast to check 15 salmon nets for live porpoises. In addition to these regular patrols by IMR researchers, the co-operation of the Jarfjord fishermen is essential to the success of the program. These fishermen check their nets 2-3 times per day for salmon, at which time they also inspect the nets for live porpoises. If a porpoise is found, it is removed from the net and transferred to the IMR boat where it is evaluated for suitability of receiving a satellite tag. If possible, the porpoise is tagged and tracked by satellite in order to follow its movements over an extended period of time. The protocols used for attaching the tags are the same that have been successfully used in the Bay of Fundy, Canada by researchers at the Duke University Marine Lab and the Grand Manan Whale and Seabird Research Station.
This project is conducted with satellite tags supplied by WhaleNet and funded by the Norwegian Research Council, with research and logistical support from the Institute of Marine Research in Bergen, Norway.
|The project was conducted with WhaleNet satellite tags and funded by the Norwegian Research Council. The research and logistical support was from the Institute of Marine Research in Bergen, Norway.|
Institute of Marine Research
Duke University Marine Lab