Abstract: The Millennium Ecosystem Assessment (MA) has identified climate change as one of the main drivers of change in aquatic biodiversity and ecosystem with a very rapid increase of the impact. Recently, the Intergovernmental Panel on Climate Change (IPCC) concluded that climate change is, without doubt, occurring and that the Earth is warming. There are some climate change winners, but scientists predict that the overwhelming effect of climate change upon biodiversity including fisheries will be damaging. The nexus between climate change, fisheries and phytoplankton is particularly strong. This study considers this ‘non-fishing effects’ on fish abundance and distribution by exploring the various roles of phytoplankton in climate change and fisheries productivity. It then discusses the need to improve our knowledge of phytoplankton as mechanisms linking climate to ecosystem changes such as fisheries productivity.