Plastic ingestion by Pacific Sand Lance (Ammodytes personatus) in the Salish Sea.

We report on micro-plastic concentrations in the guts of Pacific Sand Lance (Ammodytes personatus) which were captured in an internationally important bird area (IBA) within the Salish Sea, Canada. We collected fish (65mm - 117mm) which were buried in the subtidal habitats in the Sidney Channel IBA during 2013-2015. Eighty five percent (17/20) of the fish contained coloured (black, red & blue) plastic filaments which ranged in length from 0.59 mm to >10mm with an average of 2.14 mm (subsample n = 38 pieces). Individual fish with plastics had between 1 and 63 pieces in their guts for a grand total of 211 filaments. The fish fed primarily on copepods and cirrepeds which ranged in size from 0.3mm – 3.8mm. The diet composition includes the same breadth of taxa as regional historical sand lance samples (1966 -1968) but only the recent samples contained plastic fragments. Recent broad scale sampling of microplastics on the BC coast (Desforges et al. 2014) shows large concentrations of plastic filaments (2877/m3) in the surface waters near our study site, with most pieces within the size class 0.1mm - 0.5mm (42%) and roughly equal representation of size fractions 0.5mm - 1mm (27%) and pieces >1mm (31%). We suspect that a key source of the plastic filaments in the forage fish is the Saanich Peninsula Wastewater treatment outflow which empties into our study area from a large urban area. It is likely that the Pacific Sand Lance mistake the plastics for zooplankton prey and ingest them directly from the water. The high densities of plastic in the guts of a key forage fish in an Important Bird Area indicates the large potential for transfer of microplastics into the food web to upper trophic levels.