Undersøkelser på ål
Experiment 1: Understanding the orientation mechanisms of juvenile European eels
The objective is to test whether glass eels use the magnetic field to orient and find their way up freshwater systems. Glass eels will be collected manually: they are usually found under stones in transitional waters. They will be kept at the HI research station in Austevoll until the tests. At this stage, just before they enter freshwater, they do not need to be fed. After enough individuals (100) have been gathered they will be tested one by one in the HI magnetic facility (60.12 N and 5.21 E: Hufthamar, Austevoll, Norway).
The eels will be released back where they were collected after the tests.
Experiment 2: Estimating the stock of European eel in the coastal marine environment
The objective is to obtain a reliable estimate of the number of eels living in the sea. The background is that eel fishing is forbidden in Norway since 2010 due to the decline of the European eel population. We plan to run mark-recapture experiments in 4 or 5 different locations. Eels will be measured and tagged with PIT tags and externally with visible elastomer implants (VIE). One week later, the number of tagged eels (recaptured) will be recorded and used to calculate a population estimate. A sub-sample (200 eels at three sites) will then be euthanized and otoliths will be collected for age determination. Parasite level and maturation or “silver” stage will be assessed.
The objective is to test whether glass eels use the magnetic field to orient and find their way up freshwater systems. Glass eels will be collected manually: they are usually found under stones in transitional waters. They will be kept at the HI research station in Austevoll until the tests. At this stage, just before they enter freshwater, they do not need to be fed. After enough individuals (100) have been gathered they will be tested one by one in the HI magnetic facility (60.12 N and 5.21 E: Hufthamar, Austevoll, Norway).
The eels will be released back where they were collected after the tests.
Experiment 2: Estimating the stock of European eel in the coastal marine environment
The objective is to obtain a reliable estimate of the number of eels living in the sea. The background is that eel fishing is forbidden in Norway since 2010 due to the decline of the European eel population. We plan to run mark-recapture experiments in 4 or 5 different locations. Eels will be measured and tagged with PIT tags and externally with visible elastomer implants (VIE). One week later, the number of tagged eels (recaptured) will be recorded and used to calculate a population estimate. A sub-sample (200 eels at three sites) will then be euthanized and otoliths will be collected for age determination. Parasite level and maturation or “silver” stage will be assessed.