Amid escalating challenges such as sea level rise, ocean acidification, marine heat waves, and a notably strong El Niño event, a longstanding marine monitoring program off the Southern California coast is playing a critical role in advancing ocean science. The California Cooperative Oceanic Fisheries Investigations (CalCOFI) is recognized as the world’s oldest and longest-running marine ecosystem monitoring effort, having operated continuously since 1949.

Originally launched as a collaborative project among Scripps Institution of Oceanography, the National Marine Fisheries Service (now NOAA Fisheries), and California Fish and Wildlife officials, CalCOFI initially sought to investigate the collapse of the state’s sardine fishery. Scientists quickly found that addressing this issue required a broader, ecosystem-wide approach. Today, the program maintains a detailed grid of 75 to 113 monitoring stations extending from the U.S.-Mexico border to north of San Francisco and well over 300 miles offshore. Each season, researchers collect extensive data on plankton, fish larvae, water temperature, salinity, acidity, oxygen levels, and marine wildlife sightings.

CalCOFI’s extensive archives—housed in a temperature-controlled facility near San Diego—contain millions of samples preserved over more than seven decades. These data sets enable scientists to reconstruct historical ocean conditions, providing valuable baselines to assess contemporary changes. For example, researchers have used these archives to study the impact of past marine heat waves on fish populations or to track contaminants such as DDT discovered in historical samples. The program also actively contributes real-time observations during environmental events; during last year’s wildfires in Los Angeles County, CalCOFI scientists collected samples showing that ash and soot from nearby blazes reached as far as 100 miles offshore.

Since its inception, CalCOFI data have been cited in over 10,450 peer-reviewed scientific papers, reflecting its foundational role in marine science. In the past year alone, more than 550 published studies have relied on its data. Experts note that CalCOFI has shaped modern understanding of phenomena such as El Niño, linking regional climate variability to global impacts since the 1950s.

CalCOFI’s continuing operation is increasingly vital amid reductions in funding for other long-term ocean monitoring initiatives, such as the recent dismantling of the Ocean Observatories Initiative, a network of deep-sea monitoring stations on the U.S. West Coast and North Atlantic. Environmental advocates and scientists emphasize the need to sustain and expand ocean observation efforts as the marine environment faces unprecedented pressures from climate change and pollution.

Mark Gold, CalCOFI’s recently appointed director at Scripps, highlighted the program’s unique value: “There is a tremendous need to improve and expand ocean monitoring. This information is used in so many different ways, and we’ve seen how instrumental CalCOFI has been in understanding climate, ocean health, fisheries, risks of eating contaminated seafood, swimming in pathogen-polluted waters, you name it.”

With nearly 75 years of continuous data collection and a comprehensive archive of oceanic conditions, CalCOFI remains an indispensable resource for scientists, policymakers, and conservationists working to understand and protect marine ecosystems amid a changing global climate.