Oceanographic Data (Integrated acoustic and trawl survey of Pacific hake off the Pacific Coast)

Integrated acoustic and trawl surveys are used to assess the distribution, biomass, and biology of Pacific hake along the Pacific coasts of the United States and Canada. Scientists from the Northwest Fisheries Science Center (NWFSC) and Department of Fisheries and Oceans-Canada are responsible for conducting the survey. The survey consists of a series of transects that are oriented generally east-west, and are spaced at a nominal 10-nautical mile interval. Sea depth at the nearshore end of individual transects is typically 50 m; offshore extents are typically at a depth of 1,500 m. Geographical coverage extends from near Morro Bay, CA north to Dixon Entrance. Acoustic data are collected during daylight hours with a Simrad EK60 scientific echo sounder coupled with the ER60 software system. Trawl samples from pelagic and bottom trawls are used to classify the observed backscatter layers to species and size composition and to collect specimens of Pacific hake and other organisms. Analysis of acoustic data involves identification and delineation of backscatter layers that are attributed to Pacific hake. The biomass estimate and length-at-age composition of Pacific hake generated from this survey are used in analysis and management of the stock. This survey is conducted on a biennial basis. There is a firm deadline for producing the biomass estimate in the middle of the December following the survey. Oceanographic data collected from CTDs, XBTs, SBEs, and the ADCP