July 7, 2006
Durham, N.H. Researchers from the University of New Hampshire’s Open Ocean Aquaculture Project (OOA) launched the prototype for a new offshore, submerged fish cage in Portsmouth Harbor last week. The cage was developed in partnership with New Hampshire-based JPS Industries, Inc., with the support of the National Oceanic and Atmospheric Administration’s (NOAA) Small Business Innovation Research Program.
“Our goal is to provide an inexpensive, submersible fish cage that can be shipped anywhere in the world and survive the open ocean,” says Jud DeCew, the project engineer who helped develop the cage with the support of UNH professor of Mechanical Engineering Barbaros Celikkol.
The experimental cage consists of two concentric rings from which a drum-shaped net pen is suspended. By pumping water in or out of the inner ring, fish farmers will be able to control the cage’s depth.
“Commercially available submerged cages are designed to be moored at a fixed depth,” says Richard Langan, OOA Project director. “Being able to control the depth of this cage makes it more user friendly to operate, and more adaptable to raising different species that thrive at different depths.”
UNH researchers have begun to study the “seaworthiness” of the JPS cage now that it is moored at the OOA’s demonstration site, six miles offshore and approximately 40 feet below the surface. How will it fare when pummeled by storms and currents in the rugged Gulf of Maine? DeCew has an educated guess.
“As much as possible, we recreate ocean conditions during the design process to help companies like JPS understand the conditions the system will experience,” he explains. “We run structural and finite element analysis to see what causes material to shear or buckle. Is it 10,000 pounds of tension on the mooring line? The answers helps us suggest design modifications so the cage can withstand five times the maximum force we expect it to endure.”
JPS Industries, Inc., manufactures, installs, and maintains environmental engineering infrastructure such as baffle systems to treat paper mill wastewater and booms to manage oil spills.
“I believe that offshore aquaculture is the future of seafood production,” says Joe Santamaria of JPS, Inc., which has worked with UNH in the past on oil spill response training. “We want to develop and sell a sturdy cage that is affordable and can be easily assembled by anyone with a small crew and a crane.”