Temperature readings can tell many tales
By Lisa Cavanaugh
“When I first started fishing, I didn’t realize how important water temperature could be,” says Greg Walinski, “but obviously it plays a big role in everything we do.”
Walinski’s Cape Cod-based vessel Alicia Ann is one of 28 boats from Maine to Rhode Island outfitted with temperature sensors as part of an ongoing program from NOAA’s Northeast Fisheries Science Center Oceanography Branch.
Originally created to monitor the Gulf of Maine and the Southern New England shelf using lobster traps, the Environmental Monitors on Lobster Traps (eMOLT) project began in 2001 and has netted five million hourly records of temperature, as well as thousands of records of salinity and current velocity.
“We have nearly two decades of historical data from the lobster traps, which were pulled once a year, but we didn’t have real time data,” says project leader Jim Manning, a NOAA oceanographer based in Woods Hole. “So five years ago, we began to develop a system that was robust enough to work on other gear types and could give us daily records in real time.
“While our main objective is to collect data to adjust and validate numerical models that attempt to estimate water temperature changes, another priority is to ensure the fishermen see the data on board.”
When a fisherman hauls the probe, he can see his observation compared to what historically it should be based on climatology projections.
The eMOLT program has collaborated with fishing industry associations, academic science institutions, and research centers including the Gulf of Maine Research Institute (GMRI), the Fishermen’s Alliance, and the Provincetown Center for Coastal Studies.
Manning is able to get out of the office every couple of weeks to interact directly with fishermen, and he has some students in his lab who go dockside more regularly. “The only way this project is going to work is to have technicians at different ports to troubleshoot and fix things,” he says.
Aaron Whitman, a research technician at GMRI, has been working with fishing vessels outfitted with Electronic Monitoring cameras. “These temperature depth loggers can enhance reporting by captains,’’ he says. “My overall goal is to help fishermen, and to ultimately link the temperature measurements with the Flounders EVTR online reporting system.”
Whitman believes that this valuable data couldn’t be amassed without fishermen’s help: “It’s only fishermen who are going to all these places and can collect this information.”
Bluetooth-enabled sensors, designed by Nick Lowell of Lowell Instruments, are sheathed in protective PVC and attached to gill nets, trawlers, long lines and handlines. Once the gear is hauled up, the Bluetooth connection downloads data to a “raspberry pi,” a small touch screen computer, on each vessel.
“The data is stored to the raspberry pi’s Wi-Fi folder and also sent to a solar transmitter unit so pieces of the data are transmitted immediately via satellite,” says Whitman. “The logger takes a temperature reading every minute, and we throw out the first three and last three minutes, which are essentially the times when the sensor is going down with the gear and being hauled up, to get the most accurate bottom temperature data possible.”
Once the sensor has downloaded its data, all those temperatures show up as a graph, which can be viewed by the captain.
“Our overall goal is to help fishermen,” says Whitman. “Fishermen can look at temperature by depth, and collate that with their catch information.”
GMRI has been part of the temperature sensor program since 2017, and segued out of the program this spring, although Whitman continues to assist.
“Once we put the sensors on then the funding gets picked up by the Gulf of Maine Lobster Foundation and NOAA to support the vessels and keep it going,” he says. “But we are still in cooperation with them.”
“Most fishermen find the data really interesting. With the temperature logger, they like to see the correlation between bottom temperature and catch. One fisherman thought it was particularly neat to see variations of temperature within a single gillnet set.”
Walinski, who long lines for groundfish and harpoons bluefin tuna, agrees that more info is better.
“Having the temperature sensor on board means added knowledge,” he says. Many years ago, he and other groundfishermen realized that changes in temperature could mean the difference between a successful and unsuccessful trip. “For example, we learned that once the bottom temp on the northern edge of Georges Bank got to a certain degree it was worthwhile going out there, but if it was colder then it wasn’t worth it… So having bottom temperature in real time is invaluable.”
“Our historical data from the years of lobster trap sensors shows a clear temperature rise,” says Manning. “I send a plot of the data to fishermen once a year and they can view the day-to-day time series. They can see for themselves how the temperature of the bottom has really gone up.”
Whitman is not working specifically on climatology. His focus remains on trying to give vessel operators tools for gaining information and accurately reporting catch:
“The motivation is for fishermen to have access to all the data they are collecting so they can report better and reflect accurate stock structures. Fishermen then get an added benefit if they can use the collected data for their own efforts.”
Walinski, who also has cameras on board, agrees:
“It’s a good idea to record these bottom temperatures not only for climate change purposes but also because ultimately it might help me out with my fishing operation.”