Searching for Shrimp: A New Acoustic Study at GMRI

Thursday, December 10, 2015 by Elijah Miller

Some of the most important creatures in the Gulf of Maine are also among the smallest. Species such as herring and northern shrimp are near the bottom of the food chain and are key to a healthy ecosystem and fishing economy.  To learn more about herring, our scientists and fishermen partners have perfected a method of recording fish activity by using acoustic technology. Acoustic technology uses sounds waves to find where fish are and where they aren't.

Aucoustical Data, Photo Credit: GMRI

Now, the team is taking on a new challenge.

Northern shrimp have long been an important species in the Gulf of Maine. Shrimp spawn in deep water in the summer. In the winter, they move inshore to lay their eggs. This is when the harvest typically takes place.

Northern shrimp, photo courtesy NOAA

But there have been huge cut backs on the northern shrimp fishery in the Gulf of Maine since 2011, and no shrimp fishing in 2014 and 2015. The same will be true for 2016. This means we have little data about where shrimp are and aren't.

Now, our researchers and fishermen partners hope the acoustic technology that has been so helpful investigating herring will be useful as we seek answers for the shrimp fishery. Starting this January, our partners will apply this method throughout the Gulf of Maine to examine where northern shrimp are living.

We’ve equipped the boats of our fishermen partners with acoustic instruments called transducers. The fishermen travel back and forth in consistent patterns called transects, shooting sound waves from the transducers to the ocean floor. As the sound waves bounce back, their characteristics reveal the presence of creatures swimming below.

One challenge of acoustic shrimp surveys is what researchers refer to as “ground-truthing,” or verifying what you think you see in the acoustic data. To do that, survey vessels will deploy traps and trawl nets to check for the presence of shrimp. These small samples help verify the identity of the species according to their acoustic characteristics.

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