Fish Aggregating Devices and buoys have led to a veritable revolution in the world of tuna purse seine fishing, although a careful balance between effectiveness and sustainability has to be kept. In the search of sustainability, Satlink has developed its latest and most powerful buoy, the Satlink ISD+.
ISD+ is the first truly double echosounder solar buoy. It has been designed in the same line of its predecessor buoy, ISL+, to enhance responsible fishing while simultaneously optimize and increase efficiency and thus productivity for fishermen.
ISD+ has the same philosophy as ISL+ Buoy with the difference that the new ISD+ buoy once it makes the measurements of “fishing alert”, it gives an estimation of the predominant tuna specie. Based on this information, we can adjust the estimated number of tons of each layer, something that at the time was impossible to know.
ISD+ model has two built-in SIMRAD scientific echo-sounders. These echo sounders transmit via satellite the amount of biomass they detect below the buoy to a depth of 115 meters.

ISD+ is the most powerful buoy ever designed. It makes double sounding giving the user the ability to get more and accurate information. It is sounding every 15 minutes and transmitting the information to the vessel immediately when it detects an increase of biomass.
At the end of the day, ISD+ transmits a daily summary with the best measurement per hour giving the possibility of analyzing the behavior of the tuna during the whole day.

ISD+ performs a synchronized high resolution echo integration with both echosounders at the exact same time and then process echo response to determine dominant tuna specie based on the different response to each echosounder frequency, delivering higher accuracy of the measurements results.
Spread spectrum technology and custom designed 38 KHz transducer provides a vertical resolution of 12.5 cm. The 38KHz transducer from Simrad is the “de facto” standard in the world wide scientific community.
Thanks to the combination of the two frequencies it is possible to distinguish between bait and different tuna. In the dark period the plankton is up and can be seen very well at 38 Khz.