Fish and stats

Over the past year Keen Marine and Bays Consulting have been working together on a study to support evidence-based ecological decision-making.

The UK coastal zone supports a high diversity of fish species, many of which are caught by commercial fisheries as well as individual fisherman. Overall, the total value of the shellfish industry to the UK exceeds £250 million. Ensuring the conservation of shellfish is critical not only to support biodiversity and a healthy aquaculture in the seas surrounding the UK but also to support the fishing industry and ensure food supplies into the future.

Currently there is no single method for identifying the provenance of landed shellfish. How then can those tasked with protecting no-take zones, or working to stop illegal, unregulated and unreported fishing be helped?

Keen Marine Ltd and Bays Consulting Ltd joined forces as part of a wider study into the use of microchemical patterns in mussel shell to see if mussels could be assigned to the location in which they were grown. Mussel juveniles (spat) were obtained from a single source outside the study area and were grown in three harbours (Poole, Newtown and Langston) on the South coast of England. These harbours were selected because they have similar underlying geochemistry (the Hampshire chalks) but differ with respect to surrounding land use. The spat grew naturally on rope for a year before being harvested and their shells processed for analysis.

Using a high resolution Inductively Coupled Plasma Mass Spectrometer the chemical composition of the shells were measured for 16 different trace elements that included common trace metals and some rare earth elements. The elements were standardised with respect to calcium which is the predominant component of mussel shell before being analysed using a range of mathematical techniques.

The analysis was carried out as a “double blind” experiment so Bays Consulting had no idea which shells had come from which location. Even so Bays Consulting can report that it was possible to identify three distinct groups with a robust level of accuracy in grouping mussels from the same location.

Because the shellfish don’t move much they integrate the chemicals in the surrounding seawater for a single location over their lifespan. This offers a potential for the mussel shells to act as sentinels against which the fingerprints of species that are discriminated by time in different locations, such those found in mobile species, could be compared. This would shed light on habitat usage by transient users of near shore habitat such as the nursery environments for commercially important fish species.

Together Keen Marine and Bays Consulting are now expanding the study to include more areas across the UK and to include different types of shellfish and other fish. If you’re involved in the fishing industry or are a researcher who would like to get involved in the study we’d love to hear from you.

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