Sturlaugsson, J. and Gudbjornsson, S. 1997. Tracking of Atlantic Salmon (Salmo salar L.) and sea trout (Salmo trutta L.) with Icelandic Data Storage Tags. Pages 52-54 in Boehlert, G.W., editor. Application of acoustic and archival tags to assess estuarine, nearshore, and offshore habitat utilisation and movement by salmonids. NOAA Technical Memorandum. NOAA-TM-NMFS-SWFSC-236. 2 p.
Jóhannes Sturlaugsson, Institute of Freshwater Fisheries, Vagnhofdi 7, 110 Reykjavik
Iceland. Tel: (+354) 567 64 00 Fax: (+354) 567 64 20 E-mail:johannes@veidimal.is
Sigmar Gudbjornsson, Star Oddi Ltd., Vatnagardar 14, 104 Reykjavik Iceland
Tel: (+354) 533 6060 Fax: (+354) 533 6069 E-mail: star-oddi@star-oddi.com
Web site: http://www.star-oddi.com
The data storage tag (DST) was developed in Iceland by the engineers at Star Oddi
Ltd. in co-operation with fish biologists at the Institute of Freshwater Fisheries and the
Marine Research Institute in Iceland. These tags record series of measurements from
the environment of the fish. They record pressure (depth), temperature and
conductivity (salinity). The small size, low weight and cylindrical shape of these data
storage tags make it possible to use the tag on relatively small fish.
The Institute of Freshwater Fisheries has used the Icelandic DSTs in Icelandic waters
on Atlantic salmon (Salmo salar L.) from 1993-1996 and on sea trout (Salmo trutta
L.) from 1995-1996 (Sturlaugsson 1995; Sturlaugsson and Johannsson 1996 and
1997). In addition, the Institute of Freshwater Fisheries has participated in research
on Baltic salmon (Salmo salar L.), where these tags were used, from 1995-1996
(Karlsson et.al. 1996). The salmon were tagged externally, but the sea trout were
tagged both externally and internally. A total of 310 salmon and 110 sea trout have
now been tagged with DSTs in Icelandic waters.
In the DST tagging experiments in Icelandic waters, the main aim was to study the
homing migration of salmon in coastal waters and the sea (feeding) migration pattern
of sea trout. These studies were the first instances of DSTs used in research on these
species. The Icelandic DSTs are both the smallest and, by far, the least costly data
storage tags on the market. Therefore, the Institute of Freshwater Fisheries has been
able to tag and recapture high numbers of fish of diverse sizes (39-96 cm). This was
done in order to determine, as closely as possible, the common behaviour of these
migrants. Different intervals between recordings were used to examine more closely
the swimming behaviour (1,5 minute intervals) and diurnal rhythms (DSTs with two
different measuring time series, that are repeated). In the case of salmon, different
environmental circumstances were used to look at possible effects on the migration
pattern. As an example, salmon were released both coastally and off-shore at varying
depths. They migrated both against and along the main sea currents over distances
ranging from 25-420 km (shortest sea route). Control groups of salmon were tagged
with DSTs and kept in net pens in the sea, enabling comparison with the salmon
migrating at that time.
The use of DSTs provided new methods of sampling series of data directly from the
fish´s environment, and over longer periods of time in the sea than previously
possible. For example, we have received a series of vertical movements and
corresponding water temperatures, from the sea trout studies, for time periods up to 5
months. These data series were also the first instances of such measurements that
included the sea phase throughout the study and the freshwater phase before and after
sea migration.
A high recapture rate of tagged salmon (20-60 %) gave large series of recordings
showing that the salmon spent most of their time close to the sea surface, as has been
reported. But, the recordings also included much information concerning the poorly
documented diving activity that occurs occasionally. This new information included
dives made by the salmon down through the thermocline, and dives that were both
deeper (down to 153 m) and faster (vertical speed up to 0,73 m/sec) than had been
reported previously in coastal waters. The reasons for the diving activity of homing
salmon are not always the same. Certain known facts or hypotheses give these
reasons for dives while homing: excursions to scan the different environmental
parameters as cues for orientation, selective tidal transport, thermoregulation, escape
behaviour, and feeding (seldom).
The salmon experienced diversity in the temperature and salinity, and the largest
changes in a short time were recorded at the same time as excursions into deep water,
estuaries or rivers. Examples of extreme changes in temperature and/or salinity in a
very short time are good indicators of the versatility of salmon. The salinity sensor
was first used in 1996, and the first results show very interesting behaviour regarding
the coastal migration, especially in relation to the estuaries. The water temperature
recorded reflects the vertical, estuary or river migration pattern and also gives
possibilities for tracking the horizontal location of migrating salmon, in general, close
to the sea surface over large areas. By comparing temperature data from a DST to sea
surface temperature data from satellite measurements, it is possible to locate the area
(temperature zone) to which the fish are migrating. Because the salmon is frequently
in close proximity to the surface, the sea temperature in coastal waters is often
correlated to the air temperature in the area. Relatively high temperatures experienced
by salmon, combined with their common non-feeding behaviour during spawning
migration, resulted in as much weight loss as 10% within 1 month.
The on-going development will result in a release of the new generation DST 300 in
November of this year. Reduction of size and weight has been the main object (Table
1). The next steps taken in the DSTs´ development in Iceland will involve further
reduction of size and weight, expansion of memory, expansion of life time,
development of new sensors (5) and specification of complete customer chip
solutions.
The data storage tags will be very important research tools in fisheries research in the
future. They will open new methods of studying the behaviour and environment of
fishes, not the least of which will be the anadromous fish. This is due to the fact that
the DSTs enable unique possibilities regarding sampling continuous series of special,
behavioural, and environmental information from areas and over time periods where
other sampling methods can not be used, or are both too difficult to use and too costly,
which often results in limited data. This new dimension in research of fish will
therefore add valuable information to our understanding of fish behaviour and their
reactions to their environment. Additionally, the results from DSTs tagging can, in
some instances, be useful in improving the traditional sampling methods.In the
coming years, the Institute of Freshwater Fisheries will continue to use DSTs in
research on salmonids in the sea. In the case of Atlantic salmon, the main activity will
be in tagging experiments involving feeding migration in the sea, with a combination
of tagging of kelts and large smolts/postsmolts. This will also introduce very
interesting ways of comparing growth to sea temperature circumstances.
Karlsson, L., Ikonen, E., Westerberg, H. and Sturlaugsson J. 1996. Use of data storage tags
to study the spawning migration of Baltic salmon (Salmo salar L.) in The Gulf of
Bothnia. - ICES. C.M. 1996/M:9. 16 p.
Sturlaugsson, J. 1995. Migration Study on Homing of Atlantic salmon (Salmo salar L.) in
Coastal Waters W-Iceland - Depth movements and sea temperatures recorded at
migration routes by data storage tags. - ICES. C. M. 1995/M:17. 13 p.
Sturlaugsson, J. and Johannsson M. 1996. Migratory pattern of wild sea trout (Salmo trutta
L.) in SE-Iceland recorded by data storage tags. - ICES. C. M. 1996/M:5. 16 p.
Sturlaugsson, J. and Jóhannsson, M. 1997. Migration study of wild sea trout (Salmo trutta L.)
in SE-Iceland: Depth movements and water temperatures recorded by data storage
tags in freshwater and marine environment. Proceedings of Fifth European
Conference on Wildlife Telemetry. Strasbourg, France 25 -30 August 1996. 10 p. (In print).
HOME
