Acronym NA
Category
Aquaculture
Title Pilotprosjekt: Markører av sjeldne jordmetaller - Pilot project: Markers of rare earth metals Programme National Programme
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National Coordinator Magny Sissel S. Thomassen Coordinator email post@nmbu.no
Coordinator institution
NMBU - Norwegian University of Life Sciences (Norway)
Institutions involved
NA
Start year 2004 End year 2007 Funding (€) € NA Website https://www.fhf.no/prosjekter/prosjektbasen/542012/ Summary "Origin marking of farmed fish is a current topic for several reasons, and several different principles, including internal electronic tags, different genetic markers and DNA fingerprinting, have been considered. The use of chemical elements has also been studied. The reason is that many of these occur in low concentrations in nature, so that fish with elevated levels of such elements will be of known origin.
Use of rare earth metals (rare earth metals, REMs) has, among other things, been tested on salmonids. REM is found in the bones of many fish species in very low concentrations (ng/g range). Most are non-radioactive, easy to handle and have a long retention time in bone tissue. For example, Ennevor and Beames (1993) found that lanthanum and cerium marking of salmon fry could be traced for 10 months. Similarly, Giles and Attas (1993) found that detected levels of dysprosium, europium and samarium lasted for a minimum of 2 years in rainbow trout. The levels of samarium were unchanged during this period. No adverse effects on growth or survival were detected in these studies.
In most reported studies with fish, the rare earth metals are either injected into the fish or dissolved in the water. As these will not always be ideal solutions for the possible use of such markers in the Norwegian aquaculture industry, there was an interest in investigating the possibility of marking salmon through the addition of the rare earth metals to feed. Many of the rare earth metals are commercially available as oxides, chlorides and the like. While the oxides are poorly soluble and therefore difficult to absorb in the intestine of, for example, fish, the chlorides are generally more easily soluble in an aqueous environment and will therefore be more easily absorbed from the intestine. Based on the general knowledge of the ""bone-seeking"" properties of rare earth metals, and based on what is described in the experiments mentioned above, there is reason to expect that after absorption from the intestine these will accumulate in e.g. bone tissue in fish.
One imagines that smolt can be marked with these markers during a short feeding period where chlorides are added to the feed, and then be detectable in bone substance for longer. The type and amount of marker in bone substance can be analyzed with the technique ICP-MS for earth metals. This is a method that is very sensitive, and which can therefore make it possible to use relatively low levels of the individual markers, and also make it possible to detect the marker over a longer period of time.
Since, as mentioned, there are a number of such chlorides available (13 different ones listed with one supplier), one can imagine that the different farms in a region mark their fish with different markers. In this way, any escaped fish can easily be traced back to the individual facility. If necessary, combinations of two or three markers can also be thought of as being used, you then get a kind of genetic imprint that is characteristic of the individual plant. In this way, the number of possible combinations is high, and should not be limiting for the utilization of the concept. Alternatively, all fish belonging to a particular company can be marked with the same indicator combination, then it will be easy to find the owner, who then has to discover which of the company's locations has had an escape. One can also imagine that fish from a smolt facility can be marked with a marker, after which other markers are used in marine facilities. In this way, fish can be identified back to the smolt facility, possibly to both the smolt facility and the sea facility.
Performance target
To investigate whether naturally occurring, but rare earth metals can be used via the feed as part of the ""origin labeling"" of farmed salmon.
Results
The results from this pilot project are promising, and the conclusions can be said to be quite clear:
1. The salmon clearly take up both Yttrium and Dysprosium when these are mixed in the feed as chloride salts, and these elements are also found in the liver, bones and scales.
2. In the case of short-term feeding, a dose of around 1 g/kg of feed must probably be used to obtain a safe difference from background levels. But it is probably possible to use lower levels (down to 100mg/kg) if these elements are added to the feed over a longer period of time.
3. ""Washing"" data suggests that the accumulated elements remain in the bone structure, and can thereby be detected for a longer time after feeding.
4. Through simultaneous analyzes of other natural trace elements, the certainty in the decision whether a single fish is ""tagged"" can probably be strengthened. This adds very little to the analysis costs, but more and more comprehensive analyzes of ""natural"" relationships between elements must be carried out.
5. In this pilot study, Yttrium chloride and Dysprosium chloride were used. The salmon turns out to have a low natural content of Dysprosium, which suggests that this element is possibly somewhat more usable than Ytrium, where the salmon has a higher background level. However, there are a number of other rare earth chlorides available and a test of a few more of these would be interesting.
6. The addition of these rare earth metals to the feed did not seem to affect the fish's growth or well-being, but if their use as markers becomes relevant, the question of possible health effects must be clarified more carefully."
Keywords
Salmon;
Traceability;
Feed composition;
Escapes;
Open sea aquaculture;
Fish;
Land-based aquaculture;
Marine Region
76
Not associated to marine areas
0
Marine Region Map
