ISIIS
In-Situ Ichthyoplankton Imaging system
Current technologies available for the study of ichthyoplankton remain limited in comparison to the spatial-temporal resolution and data acquisition rate available for physical oceanographic measurements. Specifically, ichthyoplankton measurements are made primarily by use of net collections, versus high speed digital output possible for physical sampling. Though net technology has become quite sophisticated (e.g. MOCNESS), enabling vertical resolution coupled with detailed physical data, net samples still require the task of being processed manually, which is a time-consuming and costly effort. Further, nets integrate organisms over the sampling distance and depth, significantly reducing sample resolution. Biological oceanographers have been advancing methodologies for more rapid, higher resolution sampling of zooplankton via various acoustic and video technologies (e.g. FISHTV, OPC, VPR, SIPPER, ZOOVIS), but these techniques have typically been unsuccessful for ichthyoplankton, which although relatively larger are substantially rarer. To address this problem, we have built upon both existing knowledge (i.e., previously designed systems) and hardware to build a high resolution towed digital imaging system capable of sampling water volumes sufficient to accurately quantify larval fish in situ. We combine various state-of-the-art digital imaging and computer technologies (i.e. incorporating machine vision technology) with a shadowgraph lighting approach. As digital imaging technology has made major advances over the last decade, cameras now available "off-the-shelf" can produce extremely high-resolution images at very high output rates. When combined with appropriate lighting technique, sufficiently large volumes of water can be imaged to accurately quantify and identify ichthyoplankton in situ.
