Microplastic Contamination and Risk Assessment in Blue Shark (Prionace Glauca) from the Eastern Tropical Pacific Ocean

Despite concerns regarding the environmental impacts of microplastics (MPs), knowledge of the MP contamination levels and potential risks in the oceanic top predators such as blue shark Prionace glauca is limited. Here, we quantified the abundance and characteristics of MPs in P. glauca found in the eastern tropical Pacific Ocean and investigated whether MP pollution risk varies according to sex. The MPs profile in the pyloric end of the stomach of 23 P. glauca specimens (150 to 213 cm fork length) was examined. Using a micro-Fourier transform infrared spectroscope, the polymers identified as polyethylene terephthalate (PET), polypropylene (PP), and polyvinyl chloride (PVC). MPs were detected in 39.1% of specimens, up to 0.15 ± 0.38 items/g tissue wet weight, and were sized 45.87 to 3220.12 μm. The majority were fibrous in shape (83.3%) and blue in color (72.2%). Male and female P. glauca had similar abundance and characteristics of MPs, except for polymer type, with PET and PP representing the dominant type of MPs in males and females, respectively. Risk assessment models were developed to evaluate the risk of MP pollution in each specimen by using data on the MP abundance and polymer. Most individuals experienced low pollution but one male P. glauca exhibited a high ecological risk level due to the high MP abundance and detection of PVC. These results indicated potential individual specialization in MP risk levels of P. glauca . This study provided evidence and an important baseline for ingestion of MPs in pelagic shark species and is the first quantitative measure of the risk of MPs that could be used in future studies.