Fish Guidance Systems

Plastic in the food chain

Researchers in Sweden have revealed that young fish become hooked on eating plastic in the seas, in a similar way to how teenagers often prefer unhealthy food. These small particles of pollution are being consumed by fish and eventually travel up the food chain – causing potentially serious consequences for the health of other wildlife and humans alike.

Commenting on the findings, Dr Oona Lonnstedt, from Uppsala University said "I think of it as unhealthy fast food for teenagers, and they are just stuffing themselves”.

Reporting in the journal 'Science', Dr Lonnstedt's team's study explains that when exposed to high concentrations of polystyrene, perch larvae prefer the particles compared to more natural foods. The researchers have called for a ban in the use of micro-beads in cosmetics as the young perch have become smaller and slower, making them susceptible to predators.

There have been concerns in recent years about the amount of plastic in the seas. Twenty-five brands in the UK have pledged to ensure their products are free from micro-beads, while the item is banned in products in the US. Up to 50 trillion micro-plastic particles can be found in the world’s oceans, but it is thought that only a relatively small proportion of these come from cosmetics. Fibres from synthetic clothes and large pieces of plastic, which can disintegrate into small fragments has also been blamed for the pollution of the seas.

In order to observe the impact made by micro-plastics, the researchers in Sweden exposed perch larvae to different concentrations of polystyrene in water tanks. Approximately 96% of the eggs were successfully hatched where micro-plastics were not present, but this figure dripped to 81% for those exposed to micro-plastics in large quantities.

Dr Lonnstedt explained that the fish that did hatch in these waters with high quantities of micro-plastics were "smaller, slower, and more stupid" than those that hatched in clean waters. About half the young perch from clean waters survived for 24 hours, compared with those that had been raised with the strongest concentration of plastic, which were all consumed by pike in the same period.