Since 1950, the average surface water temperature at the Scripps Pier in La Jolla has risen by about 3 degrees. During this period, coastal waters have also become more corrosive and more stratified (layered by density), limiting the movement of some species. Many species of fish are now spawning earlier, or in some cases later. In this project, analyses of CalCOFI data showed that 18 of the region’s 43 most abundant fish species are now spawning between 14 days and 62 days earlier than in the early 1950s. Some of the earlier-spawning species include: jack mackerel, chub mackerel, hake, señoritas and medusafish. Chilipepper rockfish, blacksmith, two species of flatfishes and three species of mid-water fishes are among eight species now spawning 15 to 35 days later. In the next phase of the project, scientists will study the observed shifts in fish phenology in relationship to the availability of food (plankton) needed to support larval fish growth and development. The broad concern is that climate change might undermine the biological productivity of the California Current, one of planet’s richest marine ecosystems and the reason that California is home to dozens of commercial fisheries that hauled in some 373 million pounds worth more than $150 million in 2009.
Climate Change and the Phenology of Plankton and Fish Production in the California Current