Microplastic contamination in the endemic Fiji maskray (Neotrygon romeoi)

Ramona Davuke^1*Waisiki Sevakarua¹Tom Vierus²Kerstin Glaus¹

• ¹Centre for Sustainable Futures, The University of the South Pacific, Laucala Campus, Suva, Fiji, Suva, Fiji
• ²Independent Researcher, Suva, Fiji, Suva, Fiji

Plastic waste accumulates in coastal environments, posing risks to marine organisms and the human communities that depend on them. Fiji relies heavily on inshore fisheries, yet the extent and physiological implications of microplastic contamination in locally captured species remain unclear. Most work has focused on teleosts, with little information for batoids, particularly from South Pacific islands. In Fiji, batoids are common in small-scale fisheries, with the endemic Fiji maskray (Neotrygon romeoi) frequently captured and traded. To provide a first baseline for a batoid from this region, we quantified MP contamination in 21 Fiji maskrays from the Suva–Rewa–Tailevu corridor, characterized particles by size, shape, and color, and assessed physiological condition using the hepatosomatic index (HSI). Furthermore, to address a key life history gap relevant to management, we estimated size at maturity for both sexes, finding that females matured at 360–365 mm disc width and males at 369–395 mm disc width. Microplastics occurred in 71.4% of specimens, with a mean of 6.76 ± 7.80 particles per individual and no significant difference between stomach and intestine (p = 0.181). Particle sizes ranged from 63 to 500 µm, with 63 µm most frequent. Fragments predominated, with white (n = 38) and silver (n = 33) most common. There was no evidence that HSI was affected by MP presence. Together, these results establish a baseline for MP contamination and provide complementary life history information to support future contamination assessments and fisheries management in the region.