WhaleNet

Institute of Marine Research
Harbor Porpoise Program

Harbor Porpoise


Background:

Harbor porpoises are found along the entire coast of Norway, from the Skagerrak Sea in the southeast, into the North Sea and Norwegian Sea, and extending into the arctic circle and the Barents Sea. The Norwegian coast is vast, totaling a distance of nearly 22,000 km. 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. Therefore, it is not known 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.

Project Description:

Varangerfjord is a large fjord, north of the arctic circle, in northeastern Norway near the border to Russia. 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 harbor porpoises inhabiting these waters due to high concentrations of their prey species, herring and capelin. Quite often, porpoises are swimming very close to shore as they hunt for their prey. Occasionally, harbor porpoises swim near the salmon nets and become entangled. If they are not removed, they will eventually drown.

The goals of this project were two-fold. The first goal was 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.

In the first two weeks of June 1999, researchers from the Institute of Marine Research (IMR) in Bergen, Norway, worked in cooperation with Varangerfjord salmon fishermen, in the area near Jarfjord, to rescue porpoises from salmon nets and to equip them with satellite tags. In this two week period, a total of 8 porpoises were rescued from nets. Three of these porpoises (two males and one female) received satellite tags. During the field work program, researchers from the IMR traveled daily with a small boat along a 22 km (13.6 miles) stretch of coast to check 15 salmon nets for live porpoises. In addition to these regular patrols by IMR researchers, the cooperation of the Jarfjord fishermen was essential to the success of the program. These fishermen would check their nets 2-3 times per day for salmon, at which time they also would inspect the nets for live porpoises. If a porpoise was found, it was removed from the net and transferred to the IMR boat where it was evaluated. Three of the 8 porpoises recovered from the nets received a satellite tag. 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.

The 3 tagged porpoises will be tracked for as long as possible to determine if they move southward and mix with the North Sea porpoises. This information will help to interpret the genetic studies that are underway. It is hoped that researchers from the Institute of Marine Research can return to Varangerfjord in the summer of 2000, to repeat the study.


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.


Contact emails:

Krystal Tolley
(krystal@imr.no)
Institute of Marine Research

Andrew Westgate
westgate@acpub.duke .edu
Duke University Marine Lab


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