Globally, anthropogenic debris in the marine environment is increasing (Derraik 2002), with the majority of debris consisting of plastic materials (Gregory & Ryan 1997, Derraik 2002, Galgani et al. 2015). Plastic is now being found in all sections of the water column, from the epipelagic zone at the surface to the deep sea trenches of the hadopelagic zone, in all of the world's oceans (Gregory 1996, Derraik 2002, Cole et al. 2011, Fischer et al. 2015, Bond et al. 2018). Plastic is inexpensive to produce, lightweight, durable and efficient in its uses (Ryan et al. 2009). Unfortunately, it is these properties, in conjunction with its disposable nature, rapid consumption by humans and poor waste governance, that leads to its presence and persistence in oceans, estimated as taking hundreds of years to degrade (Barnes et al. 2009).

Microplastic pollution is ubiquitous in the marine environment and is ingested by numerous marine species. Sharks are an understudied group regarding their susceptibility to microplastic ingestion. Here, we provide evidence of ingestion of microplastic and other anthropogenic fibres in four demersal sharks species found in the waters of the United Kingdom and investigate whether body burdens of contamination vary according to species, sex or size. Sharks were collected from the northEast Atlantic. Stomachs and digestive tracts of 46 sharks of 4 species were examined and 67% of samples contained at least one contaminant particle. Although we acknowledge modest sample size, estimated particle burden increased with body size but did not vary systematically with sex or species. A total of 379 particles were identified, leading to median estimates ranging from 2 to 7.5 ingested contaminants per animal for the 4 species. The majority were fibrous in nature (95%) and blue (88%) or black (9%) in colour. A subsample of contaminants (N = 62) were subject to FT-IR spectroscopy and polymers identified as: synthetic cellulose (33.3%), polypropylene (25%), polyacrylamides (10%) and polyester (8.3%). The level of risk posed to shark species by this level of contamination is unknown. Nevertheless, this study presents the first empirical evidence and an important baseline for ingestion of microplastics and other anthropogenic fibres in native UK shark species and highlights the pervasive nature of these pollutants. plastics in the marine environment. Research on plastic in the marine environment has accelerated rapidly in the last decade, with numerous publications describing its impact on ecosystems and marine taxa 1-7. It is estimated that between 4.8 and 12.7 million tonnes of plastic enter the oceans every year from a variety of sources 6. Plastic is a popular material due to its durability, low production cost and efficiency in its uses 8. It is these properties, alongside its often disposable nature that leads to its prevalence in the environment for many years 9. Microplastics (defined as plastic particles < 5 mm) 10 are ubiquitous in the marine environment 11-13. Despite this knowledge, quantitative assessments of their abundance are still fairly limited 14 , although some estimates place their abundance at 5.25 trillion particles globally, weighing in at over 250,000 tonnes 5. Microplastics, in the form of fibres, fragments or beads/spheres, assimilate in the marine ecosystem via multiple avenues. Larger pieces of plastic can disintegrate over time due to UV radiation exposure, wave action and physical abrasion, eventually fragmenting into microscopic particles 15. Microplastics are also found in many everyday items used by humans including cosmetic products and can be produced by clothing wear 16-19. These can then reach the oceans via wastewater treatment plants 20. ingestion of microplastics in marine species. Ingestion of microplastics is reported in many marine species including turtles, marine mammals and fish 1,21...

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