Synthetic and semi-synthetic fibre ingestion by mesopelagic fishes from Tristan da Cuhna and St Helena, South Atlantic

As part of the Blue Belt Programme, a marine survey of British Overseas Territories funded by the UK Government, RRS Discovery trawled at depths of between the surface and 1000m around Tristan da Cuhna and St Helena in the South Atlantic. Twelve species of deep-water fishes identified from 29 specimens were compared with 2 species (2 specimens) collected from rock pools. The digestive tracts of all fishes were examined for microplastics. Neither shore dwelling species had ingested microplastics, whilst 10 of the 12 studied mesopelagic species were found to be contaminated. Overall, 65.5% of mesopelagic fishes were found to contain microplastics. Anthropogenic fibres were common especially viscose, a semi-synthetic material which is associated with sanitary products as well as other items. Anoplogaster cornuta was found to have ingested a bearded sea devil (Linophryne sp.), a cock-eyed squid (Histioteuthis sp.), a bolitaenid octopus (Japetella diaphana), remains of unidentifiable fish, crustaceans and possibly salps. These prey items were also examined for microplastics. Both Histioteuthis sp. and Linophyrne sp. had ingested fibres and these were considered “ingested particles” for A. cornuta.