AFSC/RACE/MACE: Results of 2015 acoustic trawl survey Gulf of Alaska M1501

Three trawl-resistant bottom- mounted moorings (TRBM) instrumented with newly developed autonomous battery powered 70 kHz split-beam echosounders were deployed in Shelikof Strait, Alaska (Fig. 39) to observe pollock abundance over the spawning season. The moorings were deployed from the NOAA ship Oscar Dyson 12-19 February, and recovered from a chartered fishing vessel May 5-10, 2015. The mooring locations were visited by survey vessels on four occasions to conduct mooring-related AT survey work (February 25-36, March 17-21, March 27-30, and May 5-10). A large-scale acoustic survey of Shelikof Strait (Fig. 20) was conducted on each occasion to establish the abundance and distribution of pollock over a broader area. Small-scale acoustic surveys (Fig. 39) and midwater trawl hauls (Tables 3, 10 and 11) were conducted in the vicinity of the moorings during each visit. The observations from the moorings and survey vessels will be compared to establish the spatial relationship and associated uncertainty between the mooring measurements and the ship-based acoustic-trawl survey data.