Microplastic Abundance in Rainbow Trout Life Cycle: Step by Step

Abstract

In recent years, with the encouragement of national and international authorities, researchers on plastic levels in aquaculture have begun to assess consumer health risks as well as ecological monitoring. Based on this guidance, the aim of this study is to determine the microplastic load of rainbow trout raised under routine breeding conditions without an external treatment in all developmental stages from egg to +1 year of age. Sperm, egg, fertilized egg, eyed egg, alevin or such fry, and swimming fry on growing stock (1-year-old) stages of cultured fish and commercial feeds were used for the following stages: 300–500 µm, 500–800 µm, 800–1200 µm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm. The samples were collected to determine the presence of microplastic (MP) and at which stage of this life cycle the MP has entered into the system intensively. The obtained findings showed that the total amount of MP determined in the stages without feed intake was 14 pieces, and this value increased by 557% (total of 92-piece MP) in fish that started external feeding. While no significant difference was found between the MP amounts in different feed groups, the dominant microplastic color in the feed groups was black and blue, and the polymer type was polyethylene. This general modelling, in which MP concentrations are determined in all life cycles from egg to adult in a cultured fish species, including in the given feeds, will encourage further research. Current findings have shown that any outsourced input used during growing periods can cause MP contamination to the end of fish production, processing, and storage.