SCCOOS PI Spotlight: Dan Rudnick

Dr. Daniel (Dan) Rudnick

Principal Investigator
SCCOOS Executive Steering Committee Chair
Scripps Institution of Oceanography
drudnick@ucsd.edu

Ocean Observing Tools: Autonomous Ocean Platforms,
Underwater Gilders, Ocean-Atmosphere Interactions

        “I have always loved the ocean – Our work contributes to the longest-running measurements along the California coast, a time series that was started to solve a societal problem [of fishery collapse]”

Dan Rudnick grew up loving the ocean, and once he found a place at UCSD to study the sea, he never left! Dan started as an undergraduate at UCSD, finding work in a lab at Scripps Institution of Oceanography; from there, he pursued his graduate studies at Scripps. With his vast expertise in the ocean observing field, Dan currently serves as both a SCCOOS PI and the chair of the SCCOOS Executive Steering Committee. His career has been marked by many accomplishments, but he is most well-known for his study of physical oceanography and leadership of the California Underwater Glider Network (CUGN). 

Images: Dan enjoying the ocean as a child and as an adult (images courtesy of Dan Rudnick)

Underwater Gliders are autonomous underwater vehicles that move up and down in the water column using buoyancy control. Each glider repeatedly dives from the surface to 500m (1,500 ft) depth and back along a programmed path. Using this motion pattern, gliders can detect differences in ocean water conditions at the surface versus at deeper depths and communicate the data to satellites upon surfacing. For the CUGN, each dive is about 3km (1.8 mi) long and takes about 3 hours. A full glider mission typically lasts an impressive 100 days, covering a sampling area of over 2000km (1,200+ mi). 

Image: Spray Glider (Image: WHOI), Figure illustrating CUGN dive path and glider communication (Image: Dan Rudnick)

The real-time physical and chemical measurements collected by gliders include temperature, salinity, chlorophyll fluorescence (indicating the presence/absence of phytoplankton), oxygen levels, pH, water velocity, and acoustic backscatter (a measure of zooplankton), and the data are made publicly available on the California Ocean Observing System data portal. CUGN glider tracks are pictured below, alongside an example of temperature observations produced by these missions, which allow visualization of patterns both from the near-coast to offshore, as well as from the sea surface to deeper depths.

Images: Left - The CUGN includes glider routes on four of the traditional cross-shore CalCOFI lines, Line 56.7 off Bodega Bay, Line 66.7 off Monterey Bay, line 80 off Point Conception, and line 90 off Dana Point, and on an alongshore line at CalCOFI station 60 that connects lines 80 and 90. Right - Example of temperature observations 

Gliders help scientists continue routine monitoring of important areas in order to detect changes in the coastal ocean environment that can affect our communities, such as regional climate patterns and fish populations. In fact, the long-term monitoring efforts of specific sites along the California coast began with the infamous collapse of the Pacific sardine fishery in the 1950s. 

In the 1930s to 1940s, Pacific sardine (Sardinops sagax) was the largest fishery in North America, but these fish populations crashed dramatically in the 1950s. The crash devastated local fishing communities, bankrupted the booming California canning industry, and led to a moratorium on U.S. sardine fishing through the 1970s-80s. To avoid another unexpected fishery collapse, the California Cooperative Oceanic Fisheries Investigations (CalCOFI) was established to better understand and predict seafood stability. 

Image: California sardine fishermen – The sardine fishery flourished in the early 1900s, and crashed by the 1950s (Historical image from the Monterrey Herald)

Scientists needed more data to understand how the coastal region was changing and what might have contributed to the sardine crash. Beginning in the 1950s, CalCOFI vessels manually measured ocean water samples along established paths. These long-term measurements allowed scientists to observe that, in addition to fishing pressure, larger-scale patterns, such a temperature, were contributing to differences in fish populations observed by the fishing community (Radovich, 1982). In the years since, further investigations have shown water movement patterns and periodical climatic shifts (like El Niño/La Niña - pictured below) also greatly impact our region’s primary productivity and marine food webs.

Image: Warmer ocean temperatures are observed during El Niño periods, while colder temperatures correspond to La Niña conditions, greatly impacting the diversity and abundance of marine species in the California coastal region (Image adapted from NSF/UCAR)

To enhance this monitoring effort, many of the CalCOFI traditional vessel transects have been augmented by autonomous vessels like gliders to increase observation periods and reduce costs. Our region’s fishery managers, like those at NOAA Southwest Fisheries Science Center, rely on the information gleaned from the real-time and long-term glider data to make management recommendations that protect marine resources.

"Oceanic marine heat waves and El Niño/La Niña cycles are two aspects of oceanic variability that have a significant impact on West Coast marine ecosystems. Long-term, high-quality, and near real-time monitoring of this variability supported by SCCOOS and CeNCOOS California Underwater Glider Network provides information to NOAA NMFS scientists, as well as decision-makers, for conservation and management of living marine resources”
Dr. Toby Garfield. Director, Environmental Research Division
Southwest Fisheries Science Center, NOAA

Gliders provide the necessary environmental data to inform and improve conservation initiatives for marine species, allowing our region to responsibly prosper from its wealth of natural marine resources. Additionally, glider programs have demonstrated a wide variety of applications for long-term oceanography data, which are used to better understand ocean heat waves, algal blooms, storms, marine operations, oil spill response, and weather forecasts, among others. 

Much like his gliders, we applaud Dan Rudnick for his steadfast monitoring of our important coastal region and the critical marine resources these observations support!

To learn more about gliders and their applications, check out the SCCOOS glider page, the California Underwater Glider Network, and the data available on the California Ocean Observing Systems data portal.
To learn more about fisheries and their management, see California Cooperative Oceanic Fisheries Investigations (CalCOFI) website, history of CalCOFI, and the Southwest Fisheries Science Center (SWFSC) website.

Published September 9, 2025 by Makenna Martin, Ph.D.

Keep an eye out for next month's SCCOOS Spotlight to learn about another of our Principal Investigators and community data-users!

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