Real time seawater observation network for aquaculture

We propose the construction of a seawater temperature observation network that utilizes many compact “ubiquitous buoys” to measure water temperature at different locations and depths. Seawater temperature is an important consideration when determining a suitable timing for various aquacultural operations up to and including shipping products to market. Conventionally, fishermen have used satellite-based and hull-mounted sensing technologies to determine water temperature and its distribution, information which they combine with experience and intuition to schedule their operations. One limitation of this approach, however, is that it cannot be confidently applied to the determination of the seawater temperature distribution below the surface (as it varies with, for example, the movement of water masses). There is thus a strong interest in compact, inexpensive seawater observation buoys that can monitor underwater temperature distributions in real time. In 2004, we began to develop such devices, which we call “ubiquitous buoys.” More than 100 such buoys have been installed to date within aquacultural installations and other areas along the Japanese coast; the buoys are used to provide fishermen and other operators with data on seawater temperature at various depths. We are currently working to construct a seawater observation network consisting of densely placed buoys and thereby capable of determining three-dimensional seawater temperature distributions. If this network proves successful in measuring, for instance, the speed and direction of currents or the size of water masses, it should become possible to predict changes in temperature distributions. In this report, we introduce a 20-buoy seawater observation network currently under construction within the Tsugaru Strait, off the southern coast of Hokkaido, Japan.