Climate change in the Gulf of Maine

Discarded heads of cod caught in the Arctic Barents Sea lie in a plastic container at a fish processing plant near Sommaroya, north Norway on Jan. 31, 2013. REUTERS/Alister Doyle

Palm trees and parrot fish along the Maine coast?

Not yet and not likely, and are lot of people are hoping not ever.

There’s been a lot of attention over the past week or so about warming water temperatures in the Gulf of Maine, much of it prompted by the publication in Science magazine of a study authored by a group of marine and climate scientists, most of whom are based in Maine. The attention is entirely deserved.

Increasing temperatures in the oceans has been an openly discussed issue for decades, but it wasn’t until 2012 that it really hit home for residents of New England and Atlantic Canada who live around the rim of the Gulf of Maine.

An unusually mild winter and a noticeable uptick in the gulf’s temperatures in 2012 disrupted the usual patterns of behavior and abundance of a variety of marine species in the gulf — most notably lobster, elvers, shrimp and green crabs. The past two winters have been cold (early 2013, like 2012, was relatively mild) but they have not negated the larger warming trends and symptoms, including the cancellation of the 2014 and 2015 winter shrimping seasons, that have caught the attention of coastal residents in the past few years

Historically, the gulf has been colder than much of the North Atlantic, but now it has been identified as one of the fastest-warming sections of all the oceans on the planet over the past decade.

Scientists who have spoken publicly about the phenomenon said the increased water temperature also has been making the Gulf of Maine less hospitable to cod, an iconic fish whose presence off the New England coast has been credited with luring thousands of Europeans across the Atlantic. In short, they have said (as the Science article has strongly reiterated) that climate change in the gulf is stacking the odds against the species rebounding to its former abundance.

Worth noting in all of this is that the real damage to cod in the northwest Atlantic was inflicted years ago through overfishing.

The collapse of the cod population in the Gulf of Maine happened between 1991 and 1999, according to landings data compiled by Maine Department of Marine Resources. This DMR graph shows just how steep the dropoff in landings in Maine was, plummeting from more than 21 million pounds in 1991 to 1.5 million in 1999. There’s been a little flutter up and down since then, nearing 3 million pounds in 2001 and again in 2002, but last year cod landings in Maine were at just above 400,000 pounds — less than 2 percent of the state’s haul 24 years ago.

codgraph

Others finfish species suffered the same fate, in and out of Maine. DMR landings graphs for many of them reveal fluctuations that suggest some natural cycles may have been at work, but the graphs also follow a familiar pattern as the eye moves toward the right: a spike, often in the 1980s or 1990s, followed by swift and steep declines and then an undulating trickle down to a small fraction of its former abundance.

These species include: cusk, dogfish, monkfish, plaice, skate, winter flounder, wolffish and yellowtail flounder.

Not surprisingly, warmer water has resulted in other species typically seen to the south moving into the gulf — some of which, from a ‘glass half full’ perspective, might be fished for economic gain. Black sea bass, squid, blue crab are among marine creatures relatively new to the gulf that could be caught commercially, and perhaps better managed, to provide fishermen with a sustainable source of income without the boom-and-bust cycle that has defined so many other fisheries.

Amid all this change and upheaval, however, there has been one constant over the past 25 years that has provided stability to Maine’s coastal fishing communities: the rise and overwhelming dominance of the state’s iconic lobster fishery.

As groundfish species have declined, landings in Maine of lobster have risen considerably since 1990, increasing sixfold from around 20 million pounds (where it had wavered annually since 1945) to more than 120 million pounds each year in each of the past three years. The lack of predation caused by the collapse of cod and other groundfish stocks is thought to be a major factor in the explosion of the gulf’s the lobster population.

Unlike the spikes the stand out in other DMR historic landings graphs, the graph for lobster looks like a skateboarding ramp.

lobgraph1

The price fishermen have earned for lobster has risen steadily as well, save for a discomforting drop of nearly $2 per pound between 2005 and 2012. This past summer and fall the average price offered to lobstermen has consistently held above $4 per pound — a price not seen since the pre-recession year of 2007.

Including the $457 million that Maine lobstermen cumulatively earned from the statewide catch last year, the industry is estimated to contribute well over $1 billion to the state’s economy each year as the lobster moves along the distribution chain to dealers, processors and retailers. Lobster alone represents more than 75 percent of the total value of all marine fishery landings in Maine.

Ask a Maine fishermen and he or she likely will say that conservation measures they adopted decades ago, such as throwing reproductive females back and adhering to both minimum and maximum size limits, have helped make the second most lucrative state for commercial fish landings after Alaska.

It is also worth noting here that, unlike the way cod and other groundfish were, no one is arguing that lobster is being overfished.

That has not always been the case. Scientists sounded warnings for years that the Gulf of Maine lobster population could collapse until a researcher at University of Maine named Yong Chen came up in the mid-2000s with a new, scientifically-approved model for estimating the abundance of lobster in the gulf. The model, which incorporated data collected directly by fishermen hauling traps, has eased everyone’s concerns that lobster landings could be on the verge of yet another sudden bust.

But that’s not to say there isn’t cause for worry. Everyone connected to the fishery acknowledges that catches will not go up forever, and there is concern that too much of Maine’s coastal economy is dependent on that one species. If something like a disease outbreak were to occur, the impact on the state’s economy could be severe.

Plus, it has been demonstrated that warmer is not necessarily better for lobster abundance though, so far, the lobster resource in the Gulf of Maine doesn’t appear to have been harmed by the rise in water temperatures. Some scientists have suggested that the warmer water even may have helped the survival rate of juvenile lobsters.

South of Cape Cod, however, it’s a different story. The abundance of lobsters there has dropped considerably, and they suffer from a higher rate of shell disease than in the Gulf of Maine. Warmer temperatures closer to the Gulf Stream current that moves north along the East Coast is considered to be the most significant factor, but higher rates of pollution and possible overfishing in the 1990s could be other culprits.

These are some of the points I tried to work into a relatively brief conversation I had yesterday with Tom Ashbrook on his NPR radio show On Point, in which he focused on the Science article and what kind of effects climate change has had in the Gulf of Maine and in oceans worldwide.

To listen to that conversation and a longer, more detailed one he had with Andrew Pershing of Gulf of Maine Research Institute, lead author of the Science article, click on the audio player below.

Bill Trotter

About Bill Trotter

A news reporter in coastal Maine for 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors. He writes about fisheries, marine-related topics, eastern coastal Maine communities and more for the BDN. He lives in Ellsworth. Follow him on Twitter at @billtrotter.