A GPS-RECEIVER FOR FREE SWIMMING FISH

Furdal, A.  2 Gudbjørnsson, S.1, Knudsen, F.R.2 and Godø, O.R.3
1 Star-Oddi. Vatnagardar 14, 104 Reykjavik, Iceland. E-mail: star-oddi@star-oddi.com
2 Simrad. PO Box 111, 3191 Horten, Norway. E-mail: arne.furdal@simrad.no; frank.reier.knudsen@simrad.no
3 Institute of Marine Research. PO Box 1870, 5024 Bergen, Norway. E-mail: olav.rune.godoe@imr.no

Knowledge about the migratory route of fish in the sea is limited. Information on the general geographical distribution of our commercially interesting fish resources are available, but until present is has not been possible to follow single fish or schools of fish in time and space over great distances in the oceans. Increased knowledge about the migratory route of fish in the ocean would be a major contribution to sustainable management of our fish resources. Technology that can measure the movement of fish in the ocean, would be important to our understanding of the mechanisms behind orientation and navigation of marine animals.

Data Storage Tag (DST GPS from Star-Oddi) is implanted into the fish. The tag can receive information about geographical position from satellites via sonars (Simrad) onboard ships. Information about geographical position from the ship satellite navigator (GPS) will be coded and transmitted on the sonar signal. Fish within a radius of 4 km from the ship will receive and store information about geographical position together with ambient fish depth and temperature. When recovering the fish tag, the migratory route of the fish through a whole life cycle, can be reconstructed.

At the 4th Fish Telemetry Conference (Norway 2001), we presented the technology in a historical and management perspective.  At the 5th Fish Telemetry Conference (Italy 2003) we presented results from actual test of the technology in the field.  Results were promising.  The DST GPS was able to receive position 100% up to 3 km.  Between 3 and 4 km, the position was received 80% of the time.  The table on the other side shows two columns, blue and red.  The blue column indicates the % of times when two of the same position is received in a row (Pe<1e-4).  Red column indicates the % of times when three of the same position is received in a row (Pe<1e-7). *Pe<1e-4: Probability of erroneously decoded position is 1 against 10000