Each year various plastics are being produced worldwide and disposed of improperly, fueling significant environmental concern around the accumulation of plastics in the environment and the world’s oceans. As a result, the plastic debris floating/buried in the oceans are steadily increasing every year and can be found in most large water bodies across the globe. The rapid growth of biodegradable and bio-based plastics is being observed and driven by consumers demanding environmentally friendly plastic products. However, all the known bio-based plastics are not able to degrade in marine environment. One class of biodegradable plastics i.e. polyhydroxyalkanoate (PHA) have shown the most promising potential for marine biodegradability to date. The present research focuses on studying the degradation behaviour of PHAs and their natural fibre-based biocomposites in marine environments. We simulated a marine environment (as per ASTM D7991-15) to study the degradation of PHA-based biocomposites. The results from the ongoing experiment suggests the % degradation of PHAs in a marine environment improved significantly after the addition of the natural fibres in various proportions. This evidence can conclude that PHA-based composites with natural fibres may be an efficient alternate in improving the marine degradability of PHA bioplastic. However, the effects of various experimental conditions such as temperature on natural marine degradation of plastics is still unclear. Acknowledgements This research is financially supported by the Natural Sciences and Engineering Research Council (NSERC), Canada Discovery Grants (Project # 400320); the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) – University of Guelph, the Bioeconomy Industrial Uses Research Program Theme (Project # 030255); and the Ontario Ministry of Economic Development, Job Creation and Trade ORF-RE09-078 (Project #053970).