2025 Spring Bottom Longline Survey Completes 100 Percent of Stations
Since 2014, our Cooperative Gulf of Maine Bottom Longline Survey has been working with New England’s commercial fishing industry to collect fisheries data in rocky bottom habitats.
Survey Summary
Between April 24 to May 16, the Bottom Longline Survey sampled all 45 planned stations in the western and central Gulf of Maine. The survey was conducted aboard two contracted fishing vessels, the FV Tenacious II and FV Mary Elizabeth. Scientists caught 28 species during the four legs of the survey, and sampled more than 7,800 individual animals. Atlantic spiny dogfish made up the largest component of the catch, followed by:
Some species had lower catches but typically are less common in the spring than fall, such as barndoor skate, Atlantic pollock, and white hake. Scientists successfully field tested a new app that increases efficiency by connecting scientific equipment, including scales and measuring boards, by Bluetooth to automate data collection.
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Since 2014, our Cooperative Gulf of Maine Bottom Longline Survey has been working with New England’s commercial fishing industry to collect fisheries data in rocky bottom habitats. We conduct this survey every spring and fall aboard two chartered commercial fishing vessels. This complements data collected on our Bottom Trawl Survey.
Rocky habitats are a challenge to sample with trawl survey gear. Our Bottom Longline Survey addresses that concern by using longlines, which are more likely to capture species that prefer rough-bottom habitat. The survey maintains a time series of abundance, biomass, life history, habitat, and oceanographic data for commercially important fish and data-poor species.
Data collected during this survey contribute to stock assessments to support sustainable management of our region’s marine resources. This survey provides age and maturity samples to improve our understanding of life-history by complementing and filling data gaps in sampling from other surveys. Scientists also use data from this survey to answer questions about habitat, species distribution shifts and ecosystem dynamics.
The spring Bottom Longline Survey overlapped with leg three of the Northeast Bottom Trawl Survey. Eighty percent of the stations sampled by the Bottom Longline Survey were “rough” or rocky habitat, while 20 percent were “smooth” bottom habitat. We sample smooth bottom habitat to compare methods between the two surveys.
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At each station the vessels deployed baited longlines 1 nautical mile in length with 1,000 hooks. As the vessel retrieved the gear, our scientists identified, weighed, measured, and sampled all of the catch.
Sampling took place at depths typically between 210 and 720 feet. Scientists drop a GoPro camera at each station to characterize the habitat they sampled.
Notable Findings
Though scientists reported relatively low catches of some groundfish species, they saw about average catches of Acadian redfish and red hake. They caught and sampled Atlantic wolffish, Atlantic halibut, and porbeagle sharks—three less commonly seen species. They also captured monkfish and an octopus on video. Finally, approximately 60 nautical miles from shore they were surprised to catch a hedgehog stuffed animal covered in mud and filter-feeding tunicates!
New Technology, New Team Member
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This spring, survey scientists field tested a new application called the Cooperative Fisheries Research System, or COFISHR, which makes collecting data more efficient. COFISHR connects scientific tools—including the electronic motion-compensated scale, fish measuring boards, and the sample-tracking barcode scanner—by Bluetooth to automate digital data collection. The scientists measured the same fish using their current app and COFISHR during three longline hauls and compared the data. COFISHR performed well and the test allowed the scientists to provide feedback to the software engineers.
COFISHR will be operational on the fall Bottom Longline Survey. It will soon be able to connect more devices, including printers that create labels for samples. It will also be able to perform data quality checks and alert users in real time of potential data entry errors.
This was the first Bottom Longline Survey for Hannah Ciarametaro, a new field scientist in our Cooperative Research Branch. She got to know and learn from the fishing community. We rely on the expertise of the two captains who have been at the helm of FV Tenacious II and FV Mary Elizabeth since this survey began. Long-time crew members are also getting more involved in the scientific sampling process.
Special Collections
Scientists collected lengths, weights, sex, condition, and otoliths (fish ear bones) to determine age. They also collected specialized measurements and samples for two research projects focused on thorny skate and Acadian redfish reproduction. Lastly, they collected 24 spiny dogfish for a Barnstable High School biology lab.
Stations Sampled
