A few decades ago, Jim Manning wanted to know what was at the bottom of the sea. And after years of studying waterways on the Atlantic coast, he says he's seen a steady change in ocean temperatures that he calls 'unprecedented.'
Manning is an oceanographer at NOAA's Northeast Fisheries Science Center (NEFSC) in Woods Hole, Massachusetts. He partners with lobstermen on the Northeast Shelf from Maine to New York, attaching low-cost temperature and depth loggers to some of the millions of lobster traps deployed throughout New England.
The project, called eMOLT (Environmental Monitors on Lobster Traps) records and plots long-term seabed temperature records.
Fishermen use bottom water temperatures to look for changes over time in their favorite locations, which might indicate lobsters are moving in or out of that area.
“Every day they go out, they wonder why does their catch change from day to day and what is it that drives the animals to one day go in the trap and others not,” Manning said. “Almost all of the hundreds of lobstermen that I’ve talked to are convinced that temperature is the big driver and what moves the animals. The more the temperature changes, the more the lobsters move. The more they move, the more [they are] exposed to the traps.”
About a dozen boats are outfitted with wireless sensors that can deliver data immediately as the fishing gear surfaces, allowing near real-time data transfer to NOAA.
Manning told AccuWeather he has seven million hourly records of temperatures, recorded over many years. He said they indicate a rise of 1 to 2 degree Celsius (1.8 to 3.6 degree Fahrenheit) in water temperature in the Gulf of Maine area.
“It doesn’t sound like much, but that is enormous,” said Manning. “That amount of warming is unprecedented in the 100 years or so of records we have.”
Research in action
Dave Casoni is a long-time eMOLT participant in Cape Cod Bay and has been a commercial lobsterman for 45 years.
He said he’s seen a slight increase in bottom water temperature over the past few years and wonders if it will be long-lasting or an anomaly.
Casoni told AccuWeather the ideal bottom temperature to catch the American lobster (Homarus americanus) is between 40 and 46 F.
When temperatures change dramatically, the lobsters either become lethargic because the water gets too cold or they move away because it’s too warm. Casoni said it’s difficult to track their paths.
“We don’t know where the lobsters are. We are going to guess over experience and years as to where we think they are going to be,” said Casoni. “And I always say we are trying to outsmart a creature that virtually has no brain.”
Oceanographers are using this data to improve ocean circulation models and to study the changes in the water’s ecosystem.
Manning said increased water temperature affects microscopic animals like plankton, and as it drifts with the currents, researchers try to estimate where the blooms of plankton go.
Since the development of harmful algal blooms and their release from the ocean bottom is partially triggered by temperature, Manning said the timing of the blooms will change year to year.
“The transport of these planktonic particles is obviously related to the ocean currents, particularly near the surface,” Manning said. “We need to find low-cost ways to measure these parameters over very long multi-decadal periods.”