Dr Clive Trueman, who is based at the National Oceanography Centre, Southampton said:
"Salmon farming is a big, intensive business. In 2006, around 130,000 tonnes of salmon were farmed in Scotland for the table. Wild populations of Atlantic salmon are in serious decline across their whole range and the total wild population returning to Scottish rivers in the same year is estimated at less than 5000 tonnes. Wild fish are rare and expensive so there is a strong incentive for fraudulent labelling. Farmed fish also escape into rivers, harming the wild population. Unfortunately, it can be difficult to distinguish between farmed and wild fish"
The new work which was done in collaboration with the Scottish Association for Marine Science (SAMS), Oban, will help crack this problem.
Fish scales are formed from the same chemicals as bones and teeth and grow like tree rings, preserving a chemical record of the water the fish lived in throughout its whole life. Scales are easy to collect, and can be removed from fish without harming them – which is important when studying an endangered population. The team discovered that levels of the trace metal manganese were always much higher in fish of farmed origin.
"This is probably caused by manganese supplements in fish food, and also because conditions underneath the fish cages promote recycling of manganese in the water column," says Dr Elizabeth Adey from SAMS, lead author on the research.
Using relatively simple techniques, the team was able to distinguish between farmed and wild fish with 98% accuracy.
"Because of its non-destructive nature, this technique could be used to assess the proportion of farm escape salmon present in any river, and therefore identify where additional conservation and wildlife protection measures are needed," says Dr Trueman, a geochemist with the University of Southampton's School of Ocean and Earth Science, based at that National Oceanography Centre.
Concern over declining numbers of wild Atlantic salmon has led to the closure of most fisheries, and the growth of salmon farms has been implicated in the decline of the wild fish. In 2000, more than 400,000 fish escaped from farms in Scotland. This is a problem as farmed salmon are not adapted to the local environment, and if they breed with the wild stock, the resulting offspring are less likely to survive to adulthood. In some years, the number of fish that escape from farms in Scotland exceeds the total number of wild fish, and in some Norwegian rivers more than half of all fish are of farmed origin.
It is particularly difficult to distinguish between a farm origin and wild origin fish if some time has passed after the fish escaped, and that is why the new method should prove valuable.
The team also found differences in the chemistry of scales between fish farms, which might allow researchers to identify individual farms responsible for the release of wild fish – although this would require additional work.
The research was supported by the UHI Millennium Institute.
For more information contact the NOCS Press Officer Dr Rory Howlett on +44 (0)23 8059 8490 Email: email@example.com
Images are available from the NOCS Press Office (Tel. 023 8059 6100).
Scientist contact: Dr Clive Trueman: email firstname.lastname@example.org; telephone +44 (0) 23 8059 6571
E. A. Adey, E. A., Black, K. D., Sawyer, T., Shimmield, T. M. & Trueman, C. N. Scale microchemistry as a tool to investigate the origin of wild and farmed Salmo salar. Marine Ecology Progress Series 390, 225-235 (2009).
The research was supported by the UHI Millennium Institute.
The National Oceanography Centre, Southampton is the UK's focus for ocean science. It is one of the world's leading institutions devoted to research, teaching and technology development in ocean and earth science. Over 500 research scientists, lecturing, support and seagoing staff are based at the centre's purpose-built waterside campus in Southampton along with over 700 undergraduate and postgraduate students.
The National Oceanography Centre, Southampton is a collaboration between the University of Southampton and the Natural Environment Research Council. The NERC royal research ships RRS James Cook and RRS Discovery are based at NOCS as is the National Marine Equipment Pool which includes Autosub and Isis, two of the world's deepest diving research vehicles.
Dr. Rory Howlett | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences
16.07.2018 | Physics and Astronomy