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Finding Maine's Shrimp with Acoustics

Jun 22, 2016
2016 Issue 1

This winter, a group of fishermen, in collaboration with GMRI researchers, launched a new two-year inshore northern shrimp acoustic study. The project arose as regulators voted to extend the moratorium of the commercial fishery for the third straight year due to record low biomass. In the absence of landings data, the group hopes to collect critical scientific information and gauge the health of the fishery.

Beginning in January, ten lobstermen spanning the Maine coast conducted monthly 40-mile acoustic surveys to collect valuable data on shrimp populations. Each boat, also participating in the current herring acoustic project, has been outfitted with a Simrad ES70 echosounder that uses sound frequencies to produce and record detailed images of the water column and ocean floor. This data enables GMRI scientists to distinguish individual species based on an identifying echo signature that each species displays. From this, scientists can begin to estimate shrimp abundance. Each vessel also deployed shrimp traps and a small otter trawl to verify the acoustic data they collected. By April, the group had conducted 22 surveys, covering over 800 miles.

Additionally, because groundtruthing is such an important part of any acoustic survey, Vincent Balzano of the F/V North Star conducted five trawl/acoustic surveys. This data helped verify that what looked like northern shrimp on the echosounder was, in fact, northern shrimp.

This summer, the federal northern shrimp trawl survey vessel, R/V Gloria Michelle, which has been outfitted with the same acoustic equipment, will provide additional groundtruthing data during the summer shrimp survey. This survey is conducted in June and July and covers deeper offshore areas where cold-water northern shrimp typically congregate. Coupled with the winter acoustic surveys, this summer survey will help shed light on the status of northern shrimp populations in the Gulf of Maine.