DNA tracking of salmon

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Updated documentation, per September 2019

 

The unique DNA code for each salmon can be used to trace escaped farmed salmon back to the owner. In addition, the salmon’s DNA can provide a number of important additional information such as exact knowledge of genetic interactions between farmed salmon and wild salmon and reveal fraud in the turnover of various foods.

Tracking from egg to salmon on the plate

The DNA code is already used to confirm the correct labeling of species, origin and country of production of different foods. This is becoming increasingly important in the global marketplace. Especially for food producers, it is of great importance to be able to show responsible behavior at all stages of the value chain, and traceability is a prerequisite for a credible strategy related to brands, food safety and sustainability. The method has confidence and acceptance among consumers and authorities after long-term use in different sectors.

Figure 1. Illustration of tracing through the value chain.

In order to produce traceable salmon with TRACK, eggs from a unique parental composition and thus a unique DNA profile are made at the broodstock farm. A DNA sample is taken from all parent fish used for a specific egg delivery. The DNA information is stored in a database under a separate delivery number. Through the entire value chain from egg to salmon on the plate, a salmon can be traced back to the parent fish and owner by taking a DNA sample of the salmon that is checked against the database (Figure 1). For positive DNA hits, it is verified that the salmon originally comes from an egg batch delivered to a particular hatchery at a given time.

Genetic interactions between farmed- and Wild salmon

To increase fact-based knowledge of the extent to which the farmed salmon affects the wild salmon genetically, AquaGen and CIGENE at the Norwegian University of Life Sciences at Ås have developed a new Genetic search tool. With this method, called TRACK, we are able to distinguish between farmed salmon and Wild salmon, and quantify how much genetic interference it is from farmed salmon in a salmon river.

A more efficient breeding work

DNA information has long been used to identify genes that are related to disease resistance in salmon. For some salmon diseases there are neither vaccines nor models of infection in the lab (e.g. HSMI). If an outbreak of such disease or other measurable traits in the field and the salmon is traceable, a DNA sample from any fish can be used to find the origin of the parent fish. Since AquaGen also knows the parents’ Genetic profiles, it is possible to identify genes that correlate with high resistance to specific diseases. This information is further used in the breeding program to get a more robust salmon.

Table 1. Blind test of the method for DNA tracking of 407 salmon. All salmon with TRACK were correctly traced back to their parents and all salmon without TRACK were not mistakenly traced back to parents in the DNA register of AquaGen.

Safe answer with the tracing method

The method for DNA tracing with TRACK has been used in egg deliveries to the industry since 2014. It is analyzed for at least 50,000 gene markers in the fish’s DNA and this provides a safe response to the relationship. In order for the tracing to be carried out in the best possible way, it is important that the recipients of egg, smolt, food fish and slaughtered fish maintain good control of where the fishing group at any time is in the system (Figure 1). Several blind tests have been carried out to check that the method works in practice. Results from such a test are shown in Table 1.

Products with DNA tracking:

  • AquaGen® Atlantic TRACK

Benefits with TRACK:

  • No physical marking of fish that are transferred to sea
  • A safe identification between broodstock and offspring
  • Resistance to diseases or other measurable traits in fields can be detected through analysis of single-fish DNA profiles
  • An insurance against false accusations about escapes or fraud