Three unmanned, wind-powered surface vehicles are currently sailing autonomously from Alameda, California on a six-week journey to the eastern Bering Sea. They are expected to arrive in early July to begin the 60-day survey, during which they will cover roughly the same area normally included by standard research vessels there to estimate Pollock abundance.
The Saildrones are equipped with low-power sonar instruments known as echosounders, a fish finder technology that detects the presence of fish using sound, although it is less effective at differentiating among species and fish sizes. That’s why under normal circumstances scientists also use a net to collect a sample of fish to determine weight, length and sex of individual fish.
Stock assessment scientists may use this data along with other data collected from commercial fishing vessels to estimate the fish of fish populations annually.
But extraordinary times require extraordinary measures, says NOAA Fisheries biologist
Alex De Robertis, project leader for the Alaska Fisheries Science Center. Faced with the possible cancellation of the usual survey, they came up with a contingency plan to collect data, working closely with Saildrone and NOAA Research’s Pacific Marine Environmental Laboratory.
Testing over several years, they found that the Saildrone-mounted echosounders produced equivalent acoustic measurements of Pollock to NOAA’s survey vessels. So even without directly sample fish this summer, NOAA hopes to gather necessary data.
The Alaska Fisheries Science Center’s efforts in testing new technologies both improves operating efficiencies and enables NOAA to quickly respond when situations like this arise, according to Bob Foy, director of the science center.
The Saildrones are also equipped with solar-powered instruments to measure oceanographic and meteorological conditions. Wind, solar radiation surface temperature, and salinity measurements will be made along the way.
Satellite links will be used to adjust the course of the Saildrones as necessary. Then scientists at the Pacific Marine Environmental Laboratory will process the oceanographic and meteorological data in real time.
De Robertis said that had he been asked about this technology six years ago, he would not have thought it was possible. Now he sees it as a valuable tool for augmenting standard surveys.