Intensive Acoustic Surveys of Juvenile Herring, Prince William Sound, 2013-2014, EVOS Herring Program

These data are part of the Herring Program of the Exxon Valdez Oil Spill Trustee Council, project number
12120111-G, 13120111-G, and 16120111-G, which is a multi-faceted study to determine why herring populations in Prince William Sound remain depressed since the early 1990s.

Specifically, these data were collected to quantify cruise-to-cruise variability in acoustic estimates of juvenile herring densities and biomass in Simpson and Windy Bays, eastern Prince William Sound. Hydroacoustic (sonar) surveys were repeated over winters of 2012-2013 and 2013-2014 in both bays. Surveys were conducted during the night, when herring are known to come near the surface (which makes them more accessible to hydroacoustic methods), using a BioSonics 124 kHz digital split-beam transducer mounted down-looking on an aluminum towfin. The dataset consists of intermediary files (in CSV format) of acoustic backscatter outputted by the Echoview program in the form of the area backscatter coefficient (sa, m2 m-2) from raw acoustic source data files (in *.DT4 format generated by BioSonics DT system). Full analysis has been completed for years 2013-2014 and excludes Windy Bay due to low catches of herring. Direct capture of juvenile herring using trawl and gill nets was used to confirm the species and size of fish observed by the acoustics. The length, weight, and age estimation of captured fish are included in a related dataset entitled: Validation of Acoustic Surveys for Pacific Herring, 2010-2016: EVOS Herring Program.