Posts Tagged ‘warming of Gulf of Maine’

The Shift North in the Gulf of Maine

Wednesday, January 14th, 2015

The Big Shift North continues unabated in the Gulf of Maine.

In November 2014, cod fishing in the Gulf was banned. Some cod are still there but they are concentrating in colder, deeper water. Fishermen think this is just another conspiracy among scientists and regulators to keep their jobs, and think there are plenty of fish out there. There aren’t. Whatever cod are left from hundreds of years of overfishing and mismanagement, most have left, moving north.

A 3D view of the Gulf of Maine mostly enclosed by the fishing banks, dropping beyond them into very deep water (gomcensus.org)

A 3D view of the Gulf of Maine mostly enclosed by the fishing banks, dropping beyond them into very deep water (gomcensus.org)

That wonderfully sweet Northern Shrimp, Pandalus borealis, has also again failed to show up in the Gulf this winter in any numbers, cancelling the winter fishing season for them. They too have shifted north to colder waters.

Then there are the lobsters, living in unprecedented numbers in the Gulf of Maine – partly because their predators like cod have mostly vanished, partly because of the warmer coastal waters. Their region of greatest abundance on the Maine coast has also shifted north from the central coast to close to the Canadian border.

And Green Crabs, still considered invasive and inedible, have exploded in numbers on the shores of the Gulf which just a few decades ago was its northernmost range. They eat soft-shelled clams, decimate eel grass beds, and really need now to be harvested for something.

Meanwhile species from the warmer waters south of Cape Cod are extending north at least seasonally into the Gulf.

Juvenile Kemp’s Ridley Sea Turtles drifted north of Cape Cod in the autumn in far larger numbers than ever before – where they then still got stunned by the cooler waters of the Gulf, making the rescue effort by beach walking volunteers a far greater challenge.

Black Sea Bass, easy to fish for, excellent to eat, are increasingly common in the Gulf of Maine each summer (hookedup.net)

Black Sea Bass, easy to fish for, excellent to eat, are increasingly common in the Gulf of Maine each summer (hookedup.net)

More dramatic is the seasonal arrival of Black Sea Bass that live along the coast from the Gulf of Mexico to Cape Cod, separated into northern and southern stocks by Cape Hatteras. The fish forage along rock piles and ledges, pilings and jetties, quite easily caught by pots and by hook and line. They mature first as females, and then as they grow larger some shift to become males – they are protogynous hermaphrodites. They supported thriving commercial and recreational fisheries until they were almost fished out. Then amazingly serious regulations limiting quota, season, and sizes were enforced and the stock, especially north of Hatteras, has recovered reasonably well.

Black Sea Bass were overfished but have now recovered enough to support a sustainable commercial fishery. Recreational fishing rates are at about the same level as commercial (nefsc.noaa.gov)

Black Sea Bass were overfished but have now recovered enough to support a sustainable commercial fishery. Recreational fishing rates are at about the same level as commercial (nefsc.noaa.gov)

Now Black Sea Bass have become common enough in summer in the Gulf of Maine as far as mid-coast Maine for fishing to be regulated there as well. They eat anything they can from the seafloor, including small juvenile lobsters, but enthused recreational fishing will probably prevent them from becoming a major lobster predator.

And of course the list goes on – starfish, Blue Crabs, algae, puffins – species shift north within and out of the Gulf, following the colder water, and they shift north into the Gulf, following the warmer water. A major reorganization of the entire ecosystem is well underway.

Where is all this heading? The community may not stabilize until sometime after ocean temperatures stabilize, if that ever happens.

Sea surface temperature of the gulf of Maine has been warming gradually over the past decades, but has warmed even faster since 2004 (seascapemodeling.org)

Sea surface temperature of the gulf of Maine has been warming gradually over the past decades, but has warmed even faster since 2004 (seascapemodeling.org)

We know the Gulf of Maine is warming faster, now at about 2 degrees per decade, than almost anyplace else besides the polar regions, so the rate of change in the community is unusually rapid. But it does let us think about the kinds of global changes we will expect to face everywhere else.

At the least we can recognize that complex, unpredictable community shifts are occurring and will continue to occur, and that we need now to plan for the changes. We will have to adapt our regulatory practices for managing species of both commercial and recreational interest, finding ways to respond rapidly.

For what the Gulf of Maine is telling us is that we must expect everything to change. Soon.