EK60 Water Column Sonar Data Collected During SE1401

Kona Integrated Ecosystem Assessment Survey (SE1401, EK60). This cruise accomplished the following objectives: Oceanographic data were collected from a total of 6 CTD casts and continuous TSG measurements along a predefined grid off the west coast of Hawaii to assess the influence of physical dynamics on the region's biological productivity. CTD-mounted fluorometer measurements were carried out by two fluorometers. Biological backscatter was monitored using the EK60 echosounder system, both during trawl operations and along 7 acoustic transects (including at least one daytime and one nighttime transit of each transect). One nighttime oblique mid-water trawl was conducted prior to the net being damaged beyond repair by contact with the seafloor. Four casts of a DIDSON imaging sonar were conducted to collect high resolution information on the density of high sonic scattering layers. An ROV was deployed 5 times to investigate acoustic scattering layers and adjacent layers. Deep handline jigging was accomplished during day and night to investigate scattering layer macrofauna. Data on cetacean distribution, school size, and school composition were collected via daytime visual surveys on 9 days of transects coupled with several days of small boat survey effort. Two HARP units were deployed for passive autonomous detection of cetaceans and several sonabuoys were also deployed during daytime operations for cetacean detection and identification.