Urchins: Aimed at optimizing the juvenile grow out of the green sea urchin, Strongylocentrotus droebachiensis, using a suspended cage system

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Project Type: 

Students Involved:

Christopher Benton UNH - Department of Biological Sciences
Andrew Opatkiewicz UNH - Department of Biological Sciences
Mark Loranger UNH - Department of Mechanical Engineering
Jacob Lange UNH - Department of Natural Resources & the Environment

Faculty Advisors:

Larry Harris UNH - Department of Biological Sciences

The commercial harvesting of the green sea urchin, Strongylocentrotus droebachiensis, has become a major fishing industry in the Gulf of Maine. Due to the continued harvesting of Gulf of Maine urchins and poor natural recruitment, a successful stock enhancement plan must be employed in order to maintain an urchin fishery.

The purpose of this investigation was to develop a commercial-scale suspended underwater caging system for the cultivation of juvenile green sea urchins. The engineering component of this project was to design a cage that would be stable for a wide range of currents and the underwater turbulence associated with the environment in which it will be placed, while maximizing vertical surfaces for urchin dispersion. The biological component sought to understand urchin behavior in the cage system, while optimizing growth through examining past bottlenecks. Biological experimentation supported a positive correlation between current speed and urchin growth, and initial density trials indicated that at some threshold density urchin growth would decline. The engineering results conducted on the preliminary design proved that a suspended cage system is not only feasible, but also quite effective in reaching all of the established goals for stability and endurance. The overall system behavior presented in the analyses is positive evidence that implementation of the final commercial design is the next step in urchin aquaculture.


Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant


  • URCHINS (2002). Andrew Opatkiewicz, Christopher Benton, Mark Loranger and Jacob Lange. Advisor: Larry Harris.