Drifting Buoys Designed for the Iridium System

Traveling three thousand sea miles to meet their mothers!?—Where do you think Japanese eels hatch from eggs and grow into glass eels before coming back to coastal waters around Japan?
As a matter of fact, Japanese eels spawn in waters to the west of the Mariana Islands, which are located close to Guam Island, as shown in the map below. Larvae hatch from eggs in these waters and grow into glass eels as they are carried by the Kuroshio Current all the way from waters to the east of the Philippines. These glass eels, which have remarkable swimming ability, leave the Kuroshio Current, their cradle, as they approach the shores of Japan, in order to start new lives in rivers and brackish waters (zones where fresh water and sea water mix with each other).
Thus, glass eels are not born in coastal waters around Japan, but after being hatched from eggs travel a total of three thousand sea miles for four to five months before they reach the coast of Japan—i.e., they travel three thousand sea miles to meet their mothers!

We learned this interesting story from Professor Kimura at the Ocean Research Institute, the University of Tokyo, who is the authority on Japanese eels, when we received an order for drifting buoys designed for the Iridium System from Professor Kimura, who had high expectations about our newly released buoy model. Even more interesting than the above story is the question: How do parent eels travel to the spawning grounds in the first place? And here is Professor Kimura’s answer to that question: “That’s why we need so many of these drifting buoys (laughs).”

Between July 8 and July 10, three drifting buoys designed for the Iridium System, which had just been released in June, were launched in the spawning grounds of Japanese eels. These buoys are expected to be carried by the Kuroshio Current, along with glass eels, to coastal waters around Japan sometime in or after this fall.

Data sent from buoys drifting in waters thousands of miles away reach Japan in about a minute. We will apply the latest satellite communication technology to ocean monitoring sooner than any other company and will further develop our expertise in order to receive a high evaluation for our drifting buoys as a sturdy device that supports ocean monitoring.

New Products

Drifting buoys

  • Orbcomm drifting buoy (with a storage battery)
    This buoy is designed so that location information automatically sent from a built-in transmitter can be received anywhere in Japan.
    A battery is built into the buoy and operates at intervals of ten minutes for about a week.
    This model is best suited to be used repeatedly for short-term purposes.
  • Orbcomm drifting buoy (with a solar battery)
    This model uses a solar battery, which lasts longer than a storage battery. It can be operated all year around to communicate information at intervals of two hours in northern Japan and at intervals of an hour in southern Japan.
    We have delivered more than 200 of these buoys since we released the model.
  • High accuracy drifting buoy (DGPS buoy)
    This model records highly accurate location information on a data logger with an error margin of 1 – 2 m at intervals of a second while drifting.
    It has a built-in DGPS designed to receive signals from the Japan Coast Guard’s beacons.
    It is best suited to be used for the monitoring of mild currents in restricted waters.
  • Wave monitoring GPS drifting buoy
    This compact, lightweight drifting buoy, which measures 800 mm in diameter and weighs 30 kg, is designed to monitor waves with high accuracy using only the standard GPS.
    It is capable of monitoring wave heights and directions for more than six months using satellite communication and a solar battery.
  • Compact water temperature monitoring buoy
    This model sends data on water temperature from a built-in packet communication terminal via the DoCoMo DOPA network to the e-mail address designated by the user at intervals of an hour (or at any other desired intervals).
  • Buoy system for the automatic monitoring of current direction, speed and water temperature
    This is the latest monitoring buoy system designed to monitor current direction, speed and water temperature at fixed points, which provides compact buoys, packet communication devices and a solar battery power source, all in a single package.