Northwest Fisheries Science Center

The Main Deck

Acoustic and trawl adventures in the Northeast Pacific

This portal tracks the research and sea-going activities of the Fisheries Engineering and Acoustic Technologies (FEAT) Team from NOAA¿s Northwest Fisheries Science Center.  Follow us as we use acoustics, trawling, and oceanographic sampling to learn about the Northeast Pacific Ocean.

Back deck of Bell M. Shimada
Acoustic echogram of hake
trawl catch
 

Hake!

By Sandy Parker-Stetter
Posted on January 13, 2016


Two days into the winter hake survey and we found our first adult Pacific hake.  We were ~75 miles offshore, near Coos Bay, OR, when we noticed a new pattern on the acoustics.  We fished the aggregation using our midwater trawl and confirmed that it was hake.  Score!  These hake were found over 3,000 m bottom depth, much further offshore than we see them during our usual summer surveys.  The catch was 99.1% hake, so a very clean catch.

We used the acoustics to identify the hake we fished.  Our systems are like high-tech versions of fish finders.  The acoustic “echogram,” shown below for our 38 kHz unit (we have 18, 38, 70, 120, and 200 kHz), gives us many pieces of information:

  1. How deep fish or invertebrates (referred to as “targets”) are in the water below us (these hake were at 375-400 m)
  2. How long the aggregation is (this aggregation was >6 nmi long)
  3. A sense of how many are there using color, where grey is a weak return and red is a strong return (the hake were much stronger than the small fish above them)

Photo credit Sandy Parker-Stetter

Using the echograms, we can decide if we think these are hake, if we think there are enough to catch with the trawl, and where we need to put the midwater trawl to catch them.  For this survey, the most important job in the acoustics lab is to watch the acoustic echograms to identify targets for fishing – and hopefully we’ll see more aggregations like this and find more hake!

Sandy


Tagged: Winter hake survey

Go to Top


See more blog entries:

July 2017
June 2017
February 2017
January 2017
February 2016
January 2016