Data storage tags (DST) from the Star-Oddi company have been used in Iceland for several years for tagging of fish. The Star-Oddi has now produced the DST-micro tag, that allows tagging of large smolts (80 - 100g.). The DST-micro is measuring behavioural parameters such as temperature and depth at selected time intervals and makes it possible to use temperate measurement for geo location as well.
The aims of the study are to increase knowledge on the whole marine life cycle of the salmon, from the time the smolts migrate from freshwater to the estuary to the time they return as adults to the home river. Particular aims are to get information on the temperature regime during the first and second year in the sea, temperature preferences at different times of the year and by using information on surface sea temperatures (SST) from satellites it may be possible to map migratory routes and the geographic distribution of salmon in the sea.
Knowledge on migratory routes and feeding areas of salmon allows scientists to monitor closely environmental changes in particular areas of the Atlantic Ocean. These can be used to explain changes in growth and mortality rates of the species and to build models that predict changes in population size. Information from the tags also yields information on vertical distribution of salmon in relation to temperature and diurnal temperature/growth relationships that can be very valuable in assessing the potential of salmon being intercepted by pelagic fisheries.
The project is supported by grants from the Icelandic Salmon Enhancement Fund and from the Government of Iceland.
Study location and time scale:
A small river in southwest Iceland will be used for release and capture of tagged fish. All returning adults will be screened for tags and no salmon fishing will be allowed in the river during the period of the study. Along with recovering the tags, the fish size and scales samples will be collected. At later stages (2008) it has been planned to add a release location in the north of Iceland, depending on future funding of the project.
DST tagged smolts will be released annually for a three years period (2005 - 2007) and recoveries of returning salmon will occur from 2006 until 2009.
The production of smolts for the experiment takes place at the Laxeyri fish farm in west Iceland. The smolts will be at the age of 1+ and their size 80 - 100 g.
Table 1. Technical details of the Star-Oddi DST-micro tag used in the study
| Diameter |
8.3 mm |
| Length |
25.4 mm |
| Weight |
2.5 g. in water |
| Lifetime |
12+ months |
| Memory |
43.476 measurements |
| Data retention |
25 years |
The DST-micro tags are the smallest DST from Star-Oddi weigh only 2.5 g. in water and are 25.4 mm in length (table 1). The DST tags are data logging tags and rely on being found for retrieval of data recorded by the tag. The tag will be equipped by two sensors, that record temperature and pressure (depth) at programmed intervals. The tag has a memory of 43.476 measurement or 21.738 per sensor that makes it possibly to record temperature and depth with at an 1-hour interval assuming a 24-month stay in the sea.
In the years 2005 to 2007 annual releases of 300 smolts tagged by the DST-micro tag are scheduled for the project.
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