Abstract

The rapid expansion of aquaculture in fjords and channels has raised concerns about the accumulation of marine plastic pollution. These environments are particularly vulnerable to plastic accumulation. This study assessed the composition, distribution, and abundance of aquaculture-derived plastics in fjords, archipelagos, and channels of the Los Lagos and Aysen regions in Chile. Vessel-based photographic surveys across 136 observation sites (approximate to 718 km of coastline) recorded 918 large plastic items, mainly aquaculture buoys and floating structures, concentrated in 32 coastal sectors. Most marine plastic pollution (89%) was observed in Los Lagos, where in situ observations were located near aquaculture centres (within a 1 km radius), whereas this spatial association was not observed in Aysen. Hydrodynamic modelling was used to identify potential accumulation zones of marine plastic pollution. A positive but non-significant relationship was found between modelled accumulation probability and observed plastic densities; however, spatial accumulation patterns were broadly consistent across datasets. These results highlight both the challenges of predicting marine plastic pollution in complex fjord systems and the value of integrating field observations with modelling as a complementary approach for monitoring and managing aquaculture-related plastic pollution.