Keen, Eric M.

Plankton nets are widely used to sample phytoplankton, zooplankton and small nektonic animals. Here I present a step-by-step guide to designing plankton nets that fit the objectives of a study, the logistics of sampling, and the available budget. The primary three key parameters to determine in net design are mesh size, mouth diameter, and overall net length. These 'key three' are related by the Open-Area Ratio (OAR), the ratio of effective filtering area to mouth area, which can be used to optimize sustained filtration performance for a target tow volume. Mesh size is determined first, which provides the expected porosity of the net and is primarily based on the smallest retained plankton size. Mouth size is then constrained according to avoidance capabilities of the target organisms and operational logistics. Overall net length is then set to achieve a target tow volume by meeting the minimum required OAR. All three factors can affect cost. Using this process, an array of potential net configurations can be evaluated. A case study is used to demonstrate this design process. [doi:10.7289/V5/TM-SWFSC-545 (http://dx.doi.org/10.7289/V5/TM-SWFSC-545)]

National Marine Fisheries Service (NMFS)