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
 

Redesign

By Sandy Parker-Stetter, NWFSC
February 2, 2017


Between the weather and delays, we are behind where we’d planned to be at the start of leg 2. Knowing that we still want to acoustically survey the original area, trawl, and do side ops (CTD and zooplankton), a redesign was in order.

redesign
Revised leg 2 survey plan. Completed leg 1 transects (orange boxes) and planned leg 2 transects (red) are shown

In redesigning the survey, needs for all sampling elements (acoustics, trawls, side ops) have to be considered. And then reconsidered. Here is how the redesign calculations worked.

The first (and most important) question is, “How much time do we have?”

  Answer: 11 (24-hour) days at sea

The acoustic transects and travel take the most time. We have to decide how far inshore-offshore we want to go, how much distance transiting to/from/between it requires, and make assumptions about ship speed. If we want to cover the same inshore-offshore area as the original transects at a coarser resolution, how much time does that require?

  Answer: 7.4 days to cover 1,765 nmi at 10 kt

Trawling is such an important part of our work, that it gets considered next. I’m optimistically budgeting for 3 trawls plus accompanying CTD casts on each of the red diagonal pairs. From start to finish we need up to 4 hours, so how does the math work out?

  Answer: 1.5 days to do 9 trawls and 9 CTD casts

Next up are the oceanographic and zooplankton side ops. We have new stations coming up and hope to pick up stations we missed during leg 1. Some stations are CTDs, some CTD and zooplankton vertical net, and some have CTD, vertical net, and bongo. There are 21 side stations we would like to complete. These are identified, based on logistics and discussions with collaborators, as “definitely” or “if time” stations. How much time will that take?

  Answer: 1.3 days for “definitely” and 0.4 days for “if time”

Sum total for the above plan: 10.6 days at sea

So long as the weather behaves and operations go well, the redesign is ambitious but achievable. I’ll be tracking our progress as we go to see if we need to reconsider any elements of this plan!

On another note - I wanted to thank the High School Explainers from the Exploratorium for the totally awesome card! I had a great time showing you around the Shimada and am sure that I’ll see some of you out at sea with us in the future.


Tagged: Hake, Acoustics, Winter hake research, FEAT, FRAM, Oceanography, Ecosystem, California Current Large Marine Ecosystem, CCLME, El Niño, La Niña, Climate

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