One of our many operations on this Kona IEA survey is conducting mid-water trawls. These trawls target the shallow sound scattering layer, a thick layer of small animals like crustaceans, gelatinous zooplankton, and small fish.
Caption: The thick layer of backscatter near the surface, shown here as a blue layer towards the top of the image, is the shallow scattering layer, which we target with our nightly trawls. The 38 kHz image also shows deeper scattering layers near 500 and 600 m.
Studying what we catch during these trawls helps us better our interpretation of EK60 echosounder data and provides information on ecosystem structure and fish population connectivity. We’ve conducted 12 trawls, with two trawls at each of six stations. Each night we seem to catch something interesting or surprising. Here’s a bit of what we’ve caught:
Caption: A seahorse and other larval shore fish
Caption: Gelatinous zooplankton
Caption: Two cookie cutter sharks
Caption: A dragonfish. You can see its lure, which hangs down from its jaw to trick prey into approaching.
Caption: A small puffer fish and other shore fish