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

Measuring hake

By Sandy Parker-Stetter
January 31, 2016

Hake on the electronic measuring board.  Photo credit Sandy Parker-Stetter (NWFSC)

After a midwater trawl catch comes on board, the hake are divided into males and females and measured for length (from snout to tail). Our wet lab team uses electronic measuring boards that are interfaced with a computer program – no paper for us. The computer program tracks every measurement, weight, and sample (like stomach content, otolith bone, or genetic collections) that is taken from an individual fish, and even has a bar-code reader for scanning labels on bags or vials! This crazy efficient system allows us to link all the attributes of an individual fish. Alicia Billings, on the NWFSC-FRAM Fisheries Engineering and Acoustic Technologies team, is constantly fine-tuning and developing this system to be easier to use, faster, and even more powerful. Thanks, Alicia!

A range of hake sizes caught in the trawl.  Scissors and quarter for scale.  Photo credit Sandy Parker-Stetter (NWFSC).  Fish styling by Allen Shimada (OST).

Every trawl contains a range of fish sizes, but the average and the largest/smallest lengths can be very useful. We’re interested in knowing if there are length differences within an aggregation (large on one side, small on the other?) or if there are length differences across aggregations (large fish in one aggregation, small in another?). 

We’ve had a few opportunities to sample an aggregation more than once. We’ve been a bit surprised at how consistent lengths have been from trawl to trawl, making us think that hake of different sizes may mix within a single aggregation. 

We’ve also had the opportunity to sample multiple aggregations spaced along the coast.  Again, the mixing of sizes has been a bit unexpected.  We’re now down in the Southern California Bight, so our sampling (and comparisons of lengths) continues.

Tagged: Winter hake survey

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