Written by: Jess Van Vaerenbergh, USF CMS graduate student
Researchers have long known that fish reproduce in the Gulf of Mexico, but which species spawn where remains a mystery.
Researchers at the USF College of Marine Science (CMS) may soon solve that mystery thanks to Garrett Miller, a graduate student in biological oceanography at CMS, and an unassuming device called a CUFES (pronounced, coofs).
The CUFES — short for Continuous Underway Fish Egg Sampler — is a device that’s smaller than a mini fridge with long, flexible tubes to suck up seawater.
The original CUFES was invented in 1993 by biologist David Checkley to study fish spawning patterns in California. After a successful trial run on a National Oceanic and Atmospheric Administration (NOAA) vessel, a long-term collaboration was created with NOAA’s Fisheries Service, the California Department of Fish and Wildlife, and Scripps Institution of Oceanography (SIO).
Four decades later, CUFES devices have helped track fish spawning and manage fisheries around the world.
The CUFES operates by using a pump to draw in water from the side of the vessel. This water is then pushed through a large flexible hose into a box called a concentrator. Inside the concentrator, the seawater is filtered through a fine mesh bag, which allows the eggs to remain. The eggs are then directed into a small clear tube and collected in a container.
Every 30 minutes, the crew empties the sample into small vials.
When researchers at CMS wanted a new way to study spawning in the Gulf of Mexico, Christopher Stallings, a professor of biological oceanography, had a bold idea: why not build a CUFES from scratch?
Miller, a student in Stallings’s lab with a knack for engineering and an apprentice in the machine shop on the CMS campus, were up to the challenge.
Miller and other members of Stallings's lab first tried to track down the blueprint but all they had was a photo of NOAA’s CUFES. Undeterred, graduate student Ian Williams, who worked with the original device in previous research, traveled to the NOAA Southeast Fisheries Science Center in Pascagoula, Mississippi, and brought an original CUFES back to St. Petersburg, where Miller used it as a model.
Miller spent the next few days recording each measurement on a yellow notepad to create a rough guide.
"I had to measure every single part of the machine by hand,” Miller said. “Each opening, the thickness of each piece of metal, and even each screw. We had to measure within one one-thousandth of an inch, so a tape measure was no longer the appropriate tool.”
During the initial welding process of the main CUFES box, Miller used clamps to apply pressure in specific directions to prevent the metal from warping as it cooled. This also allowed for small, short welds to make sure the structure was aligned before the final weld. Picture Credit: Garret Miller
Miller turned instead to a specialized tool called a micrometer.
“Our most precise micrometers can actually even measure down to within a tenth of a thousandth of an inch,” he said. “That’s super tiny.”
Miller spent hours in the machine shop at CMS constructing the new device from scratch. Miller, alongside fellow machinists Jim Mulhollan and Guy Grant, faithfully recreated the CUFES piece by piece, while also making a few upgrades. With help from colleagues, including the engineers at the Ocean Technology Group, he used a variety of skills and tools to turn the rough sketch into a fully functioning device in just four months.
In late June, a crew of four from CMS took the CUFES on its maiden voyage across the entire West Florida Shelf aboard the Florida Institute of Oceanography’s R/V Weatherbird II. Williams, who served as chief scientist, and I represented the Stallings lab. Alexis Mitchem and AJ Gross participated as members of the lab of Mya Breitbart, a Distinguished University Professor of biological oceanography at CMS.
The CUFES ran 24/7 while the crew traveled 2,200 miles over 11 days to collect fish eggs from the Florida panhandle to the Dry Tortugas. The device persevered through the elements despite ingesting a few pieces of sargassum and one unfortunate flying fish.
The eggs it collected will be analyzed at the college by the Breitbart lab.
The CUFES ran around the clock collecting samples – and so did the crew. Those that worked through the night witnessed colorful sunrises every morning. Picture Credit: Jess Van Vaerenbergh
The data collected on the cruise will contribute to the Spawning Habitat & Early-Life Linkages to Fisheries (SHELF) project, which is funded by the Florida RESTORE Act Centers of Excellence Program (FLRACEP) under the Florida Institute of Oceanography. The SHELF project seeks to determine the timing and locations of spawning fishes in the Gulf of Mexico by using DNA from the collected eggs.
The crew collected a diverse set of samples over 11 days. These are just two examples, one which included a mix of phytoplankton and fish eggs, and the other with crab larvae. Picture Credit: Jess Van Vaerenbergh
CMS researchers aim to develop a dataset for monitoring changes in the spawning efforts and locations of important fish species that can be affected by climate change, fishing, and habitat quality.
Williams will use the CUFES to study eggs collected from a reef system where the Stallings lab conducts seasonal visual reef fish surveys. By comparing the collected eggs to the adult abundances of certain species, William hopes to reveal how fish use the reefs for reproduction.
Alexis Mitchem, working in the Breitbart lab, will focus on using DNA from each egg to identify fish species.
Future work will include cruises through 2026 to compare the results seasonally and annually, providing a better understanding of when and where certain fish species are spawning across the West Florida Shelf.
The crew was welcomed back to campus after 11 days at sea collecting fish eggs for the SHELF project. Photo credit: Mya Breitbart
As CMS researchers continue their study, the CUFES will play a crucial role in unraveling the mysteries of fish spawning in the Gulf of Mexico.
Each expedition gathers valuable data that will significantly contribute to the SHELF project's goal of understanding the spawning efforts and patterns of important fish species.
The construction of the CUFES was not only a notable achievement for Miller and his colleagues, but also a symbol of the dedication to understanding our marine environments that drives CMS researchers forward.