Fish prefer eating plastic to real food, study says

Researchers publishing a new study on plastic contamination of the world’s oceans find that fish prefer eating microplastic particles “like they were teenagers eating fast food,” a result causing serious damage to worldwide fish stocks.

The production of plastics has bloomed over the past 50 years from 15 million tonnes in 1964 to 311 million tonnes in 2014, a number which is expected to double again over the next 20 years, according to a World Economic Forum report. About 8 million tonnes of plastics make their way to the ocean each year, which equates to dumping one garbage truck of plastic into the ocean every minute, according to a World Economic Forum report, and offering up the disturbing projection that by the year 2025 the oceans will contain one tonne of plastic for every three tonnes of fish and by 2050 there will be more plastic in the ocean by weight than fish.

Once in the environment, plastics take hundreds and even thousands of years to break down. Through exposure to ultraviolet radiation, water and physical processes, plastic objects end up in the oceans as microplastics – deemed any particle less than 5 mm in length -which studies have shown can play serious havoc with ecosystems through their accidental ingestion by sea life.

But until now, the extent to which microplastics have supplanted normal food supplies for fish has been unknown.

Scientists with the Department of Ecology and Genetics at Uppsala University in Sweden studied the effects of exposure to microplastics on perch larvae and found that not only are egg development and hatching rates negatively impacted by microplastic concentrations in the environment but so are behaviour patterns. The researchers found that 10-day old fish larvae reared in environments with average levels of microplastic pollutants (registered in the Baltic Sea off the coast of Sweden as between 7,000 to 10,000 plastic particles per cubed metre of water) were less active, displayed weaker predator responses and actually favoured ingesting the non-nutritious microplastic particles over their natural freely swimming zooplankton food source.

“They all had access to zooplankton and yet they decided to just eat plastic in that treatment. It seems to be a chemical or physical cue that the plastic has, that triggers a feeding response in fish,” says Dr. Oona Lonnstedt, co-author of the study. “If early life-history stages of other species are similarly affected by microplastics, and this translates to increased mortality rates, the effects on aquatic ecosystems could be profound,” say the study’s authors.

A 2015 report by the advocacy group Ocean Conservancy offers up a plan to cut plastic waste leakage into the ocean by 45 per cent over the next ten years, at a cost of only $5 billion USD a year. “Considering this is a global environmental challenge impacting sanitation and health, land values, important sources of global protein, and the growth of the consumer goods and packaging industries, an estimated $5 billion scale of intervention makes this one of the most solvable of the environmental challenges we collectively face,” says Martin Stuchtey, director of the McKinsey Center for Business and Environment, a research partner on the report.

In outlining specific land-based solutions to the problem the report points to five priority countries (China, Indonesia, Philippines, Vietnam and Thailand) which collectively account for half of all global plastic leakage into the ocean.

Canada’s David Suzuki Foundation argues that individuals as consumers can help in reducing plastic waste in our oceans by refusing to buy unnecessary, disposable plastic items such as bottled plastic water and single-serve coffee pods and by cutting back on the purchasing of overpackaged goods.

More Cantech Science