Tracking salmon by using rare earth elements Magny S. Thomassen

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1 Tracking salmon by using rare earth elements Magny S. Thomassen The main object of this project is to develop a method that, both simply and cheep, can distinguish farmed from wild salmon, and at the same time track the salmon back to the farm. Rare earth elements are found in the bone structures of fishes, but in very low concentrations. Most of these elements are non-radioactive, easy to handle and have been shown to have a long retention time in bone. In my project we will test several of these elements as tracers by adding them to the feed. We will use chloride salts and the feeding period will be from 4 to 8 weeks after sea transfer.

2 As Ce Dy Er Eu Gd Ho La Lu Nd Pr Sc Sm Sr Tb Tm U Y Yb U

3 Project plan WP1: To get an insight into the background levels of rare earth elements in salmon smolt collected from different farms up along the coast. WP2: Testing of several elements in feed for 1+ smolt in seawater. WP3: Studying different doses/feeding periods for 0-smolt. Spring 2012 May-October 2012 Autumn- winter

4 Analysis One of the SIMPLE things about this method is that we only need to sample some scales from the fish, put them in a small plastic bag and send them in for analysis! The analysis are done by IonCoupledPlasma-Massespektofotometri (ICP-MS). These instruments are advanced and expensive, but the analysis will still be cheep ( kr) In addition we can, for obtaining higher security, also analyse bones or otoliths (ørestener) by the same system. Otoliths will be analysed also by our collegue in Zurich. For this he will use a special method called Laser ablation ICP-MS, to see if he can measure the high consentrations at the growth zones.

5 Test of 5 different elements (=5 different «label feeds») This feeding experiment was started in May with 80 grams 1+ smolt in seawater to simulate the situation in practise when «label feeds» will be used. Chlorides of 5 different elements (cerium, lanthanum, neodymium, praseodymium and dysprosium), were used at 0,25g/kg feed, 2 tanks pr. feed. Growth measurements and sampling of fish after 5 and 9 weeks. The marker feeding ended in July after 9 weeks. The fish were then transferred to one tank (they were all PIT-tagged) and given a commercial feed, and followed for another 2 months. The test feeds were added Yttrium oxide, and faeces were sampled at 9 weeks for digestion (uptake) studies.

6 NG/G SCALES And the scales were definitely Labelled!! 9 Average of Dy Not fed DY Not fed DY S2 S3

7 NG/G SCALES Good results also for Pr (shown here) and Ce and Nd 4 Average of Pr A C B D 0 Pr-feed Not fed Pr Pr-feed Not fed Pr S2 S2 S3 S3

8 In WP1 we studied the background levels in farmed salmon GRIEG SEAFOOD FINNMARK MARINE HARVEST REG. NORD LERØY HYDROTECH BLOM FISKEOPPDRETT GRIEG SEAFOOD ROGALAND

9 Mean background values (ng/g) As Ce Dy Er Eu Gd Ho La Lu Nd 647,0 ±233,0 3,51 ±0,24 0,18 ±0,11 0,17 ±0,12 4,10 ±2,92 0,46 ±0,26 0,06 ±0,04 3,90 ±2,26 0,34 ±0,35 2,08 ±1,21 Pr Sc Sm Sr Tb Tm U Y Yb 0,60 ±0,36 12,51 ±4,73 0,37 ±0,22 327,2 ±113,7 0,40 ±0,33 0,03 ±0,03 63,73 ±28,28 5,18 ±2,03 0,14 ±0,10

10 Background levels varied, both between fish and locations 10,0 9,0 8,0 7,0 6,0 5,0 4,0 3,0 2,0 1,0 0,0 La ng/g

11 6,00 But we find a high correlation (ratios) between the contents of some of the elements Korrelasjon Nd vs. La 5,00 4,00 3,00 2,00 y = 0,5223x + 0,038 R² = 0,9536 1,00 0,00 0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0

12 Dy/Lu Since we get data for 19 elements at the same time, we can study moe than 300 ratios! (= a fingerprint of each location!) Ratio between the elements Dysprosium and Lu P<0.0001, R 2 = 64.7% B A DC C D Grieg Rog Blom 1 Blom 2 Lerøy Hydr Marin H Grieg Finn LOCATIONS Dy/Lu DC

13 Pr (ng/g) But we had one important question: Will this fingerprint stay constant over time?? 1,200 1,000 y = 3,6485x - 0,0501 R² = 0,9395 Rog 1+ 2 (Dy vs Pr) 0,800 0,600 0,400 0,200 0,000 0,000 0,050 0,100 0,150 0,200 0,250 0,300 0,350 Dysprosium (ng/g)

14 This far in the project we can conclude: By adding small doses of rare earth elements to the feed for a sort period, scales are defenitely labelled It is important to choose a label with low background levels Using ratios rather than just concentration levels gives less variation, and longer lasting differences to background levels The fingerprints obtained just by analysing background levels gives very interesting information In some instances this information may be all that is needed to pinpoint the farm

15 So a combination of a label feed and more knowledge about the background ( fingerprint ) differences is really very promising in obtaining a cheep and fairly simple method of tracking escaped salmon This is all you need Simple?