EK80 Water Column Sonar Data Collected During SD1022-201801

Summer surveys of the Chukchi Sea indicate that high densities of age-0 gadid fishes, historically Arctic cod (Boreogadus saida) but recently also walleye pollock (Gadus chalcogrammus), dominate the pelagic fish community. Adults are comparatively scarce, suggesting that either overwinter survivorship of age-0 gadids is low, or that they emigrate to other areas of the Pacific Arctic. To examine population movement, we conducted repeat acoustic surveys with saildrone autonomous surface vehicles equipped with echosounders throughout summer 2018. Results of these surveys were published in Levine et al. (2021).

The survey was completed by two 7-meter saildrone USVs. The primary water column acoustic instrument for the survey was a Simrad EK80 mini scientific echosounder system equipped with a dual frequency ES38-18/200-18CR transducer (38 kHz split-beam, 200 kHz single beam). The vessels departed Dutch Harbor, AK on 30 June 2018, conducted acoustic surveys of the eastern Chukchi Sea from 20 July to 11 September, and returned to Dutch Harbor on 06 October. The echosounder system was calibrated via the standard sphere method before and after the cruise.

Levine, R.M., De Robertis, A., Grünbaum, D., Woodgate, R., Mordy, C.W., Mueter, F., Cokelet, E., Lawrence-Slavas, N. and Tabisola, H. (2021), Autonomous vehicle surveys indicate that flow reversals retain juvenile fishes in a highly advective high-latitude ecosystem. Limnol Oceanogr, 66: 1139-1154. https://doi.org/10.1002/lno.11671