Since the early 1980s, when they landed just over 200 million tonnes (metric) of the prized fish, the annual catch is now well under 50 million tonnes and the graph shows a steady decline since times 80s. Scientists here say that the massive decline in sardine stocks in Portuguese waters is due to problems connected with phytoplankton and climate change. Here fishermen unload sardines from their trawler at Matosinhos near Porto in Portugal.