Emerging science shows a rapid heating up of the waters in the Gulf of Maine, at a far faster rate than the rest of the ocean, and it has New Hampshire’s commercial fishermen worried about business.
David Goethel, a commercial fisherman from Hampton, is catching more summer flounder these days and fewer cod. Unfortunately, he has to throw the summer flounder back, since he doesn’t have a catch permit for that species. The reason for the changing species in his nets? The Gulf of Maine’s shifting temperatures.
“Waters are warming in the Gulf of Maine, at least in the last 10 years, at really unprecedented levels,” Goethel said.
In fact, studies have shown that the waters in the gulf warmed faster than 99 percent of the ocean over the past decade. And over the past 30 years, it’s warmed four times faster than the average global rate.
This has caused fish populations to shift. Fishermen may be catching the same amount of fish, but a different composition of species, as the warmer waters are causing North Atlantic cod to huddle into deeper trenches in the southwest and species that enjoy warmer waters migrate into the gulf.
To make matters worse, Andrew Pershing, the chief scientific officer at the Gulf of Maine Research Institute, says the warming waters are causing cod re-population efforts to suffer.
“We see that in warm years, each individual female produces fewer successful babies. We also found evidence that in these warm years that fewer young fish survive,” Pershing said.
Pershing says this is because warmer waters may also be affecting plankton, which baby cod need to eat, it may invite cod’s migratory predators to stick around and feast for longer periods during the summer months and it may be directly affecting the metabolism of the subpolar species — forcing the fish to burn more energy with no extra food to make up the difference.
This is a problem for fishermen because federal regulators have already put strict limits on how many cod can be caught but haven’t adapted the permits for commercial fishermen to include the new species they are finding.
“Fishermen now may be mismatched with the permits they have to fish species,” Goethel said. “That’s an issue government is going to have to address.”
In a recent scientific paper by the National Oceanic and Atmospheric Administration, Dr. Vincent Saba came up with a new model for simulating ocean temperature projections. In it, he finds that the Gulf of Maine is ground zero for climate change due to a combination of increased atmospheric carbon dioxide and a weakening of Atlantic currents.
“[When] we projected forward, we effectively doubled the amount of carbon dioxide in the model, and what we found was the Gulf of Maine and the surrounding waters in the northwest Atlantic ... warm two to three times faster than the global average,” Saba said. “This neck of the woods, in the North Atlantic, tends to be a hotspot for climate change.”
This new model, which improves on traditional models that look at oceans at large by looking at smaller regions (Saba compares it to a high-def TV), provided findings consistent with what had been reported by other scientists, like Pershing, who have observed water temperatures rising quickly over past decades.
Essentially, the normal process of warm salty water from the south moving up through the Gulf Stream and the cold freshwater moving south through the Labrador Current is short-circuiting, according to Saba.
While some fishermen, like Goethel, are not entirely convinced this is caused by global climate change — suggesting that it may instead be a result of “multidecadal oscillation,” a normal temperature shift in the Atlantic — Saba says it’s unlikely that the rapid temperature change in the Gulf of Maine is exclusively the result of natural climate change.
Pershing says the speed of the change is noteworthy.
“It was a rate of change in temperature that few ocean ecosystems have ever experienced,” Pershing said.
With so little precedent, this puts us in uncharted waters, leaving many to speculate how this will affect fisheries in the long term.
Saba says their projections looking at the next 80 years show the gulf waters getting a lot warmer than previous, lower-definition models could have predicted.
“Our estimates might actually be conservative if business as usual continues,” Saba said. “The bottom waters can warm in this new projection by … about 4 to about 7.5 degrees Fahrenheit, which is pretty substantial for fisheries.”
Pershing doesn’t think the new science will mean even stricter cod quotas.
“It’s hard to imagine cutting the quotas back anymore,” Pershing said. “The challenge is going to be setting the quotas as the population starts to rebuild.”
But most agree that the solution for commercial fishermen should include updated permits to reflect the changing fish populations.
“In the best of times, the bureaucracy moves at a glacial pace; some people would say it moves at a geological timescale. But this requires nimbleness,” Goethel said.