Warming waters a major factor in the collapse of New England cod, study finds

October 29, 2015, Gulf of Maine Research Institute
This image shows cod fishing in the Gulf of Maine. Credit: Gulf of Maine Research Institute

For centuries, cod were the backbone of New England's fisheries and a key species in the Gulf of Maine ecosystem. Today, cod stocks are on the verge of collapse, hovering at 3-4% of sustainable levels. Even cuts to the fishery have failed to slow this rapid decline, surprising both fishermen and fisheries managers. For the first time, a new report in Science explains why. It shows that the cod collapse is in large part due to rapid warming of the ocean in the Gulf of Maine - 99 percent faster than anywhere else on the planet.

The rapid warming is linked to changes in the position of the Gulf Stream and to climate oscillations in the Atlantic and the Pacific. These factors add to the steady pace of warming caused by global climate change. In the face of already depleted cod stocks, managers in 2010 had placed a series of restrictions on harvesting this key Gulf of Maine species, but even strict quota limits on fishermen failed to help cod rebound.

"Managers kept reducing quotas, but the cod population kept declining," said Andrew Pershing, Chief Scientific Officer of the Gulf of Maine Research Institute (GMRI) and lead author of the study. "It turns out that warming waters were making the Gulf of Maine less hospitable for cod, and the management response was too slow to keep up with the changes."

Pershing and colleagues from GMRI, the University of Maine, Stony Brook University, the Bigelow Laboratory for Ocean Sciences, and NOAA's Earth System Research Laboratory, including the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, found that increasing water temperatures reduce the number of new cod produced by spawning females. Their study also suggests that warming waters led to fewer young fish surviving to adulthood.

The models used by managers over the last decade to set the quotas for cod did not account for the impact of rising temperatures, leading to quotas that were too high. Fishermen stayed within their quotas, but still took more fish than the population could sustain.

"This creates a frustrating situation that contributes to mistrust between fishermen, scientists, and managers," says Pershing. "The first step toward adapting fisheries to a changing climate is recognizing that warming impacts fish populations."

According to the report, recovery of Gulf of Maine cod depends on sound fishery management and on future temperatures. Cod are a coldwater species, and the Gulf of Maine is at the edge of their geographic range. As the ocean warms, the capacity of the Gulf of Maine to support cod will decline, leading to a smaller population and a smaller fishery.

The study shows the risk of not including temperature in fisheries models, especially for stocks like Gulf of Maine that are at the edge of their range. The warmer our climate gets, the less fisheries managers can rely on historical data.

Explore further: Codfish numbers at key fishery hits all-time low

More information: "Slow Adaptation in the Face of Rapid Warming Leads to the Collapse of Atlantic Cod in the Gulf of Maine," by A.J. Pershing et al. www.sciencemag.org/lookup/doi/ … 1126/science.aac9819

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Oct 29, 2015
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1.9 / 5 (9) Oct 29, 2015
There is no limit to the lies of the AGW Cult. Over fishing collapsed this industry in Canada and it's obvious that the even more ignorant and greedy US learned nothing from this.
4.6 / 5 (11) Oct 29, 2015
And no limit to yours either.
4.7 / 5 (13) Oct 29, 2015
Okay Anti... Please explain why everyone who runs a ship in the area is lying about the water temperature. That is thousands and thousand of people lying with no one else doing the measurements contradicting them.

Quite the conspiracy...

Seriously. At least pick feasable lies.
1.6 / 5 (7) Oct 29, 2015
1.7 / 5 (6) Oct 29, 2015
The article seems to have no numbers? Temperature increases? Stock/landing decline/unit effort over time? Not having supportive numbers makes it look more rhetoric than science. It is also long on unsupported statements:

"It (the model - not data) shows that the cod collapse is in large part due to rapid warming of the ocean in the Gulf of Maine - 99 percent faster than anywhere else on the planet." To accomplish this would seem to be a violation of basic physics and - or unknown volcanoes in the Bay of Maine.

"Fishermen stayed within their quotas, but still took more fish than the population could sustain." This would be the first time in history that commercial fishermen stayed within their quotas - and it doesn't account for foreign fishing boats.

The Bay of Maine is just one of a number of Cod Fisheries. It is difficult to understand that rising temperatures depleted the fishery. If there were rising water temps - the Cod fishery moved further to deeper waters.
4.6 / 5 (10) Oct 29, 2015

Do you understand the article is not the actual study published in the journal Science?

The link to the study is broken, (a common occurrence lately at PO) but I'm sure it is rich with data.
5 / 5 (11) Oct 30, 2015
Success! I found a full access link thru New Scientist:
4.6 / 5 (10) Oct 30, 2015
Anti, I'm confused. Your first article confirms the warming, and talks about a similar issue. The second article is a recovery in an area significantly north of new England. Please explain your rebuttle.
2 / 5 (4) Oct 30, 2015
This "study" claims the warming in the Gulf of Maine is responsible for the collapse of the cod, the other claims the COLD waters in the Gulf of Maine is responsible for the flourishing of the lobster.
2.7 / 5 (7) Oct 30, 2015
Vietvet - As a marine biologist with a career spanning 40+ years, published author of numerous peer review scientific journal articles, technical articles, industry trade articles, etc. I do understand what should go into an article (even a PR article) to be convincing of its results and of the competency of its authors. As I noted I see none of the required elements in this article. If one has convincing data in a study, why would anyone ever rely on non-quantified generalities about the studies conclusions in a PR? Like the article - this strategy makes little sense.
4.6 / 5 (11) Oct 30, 2015
This "study" claims the warming in the Gulf of Maine is responsible for the collapse of the cod, the other claims the COLD waters in the Gulf of Maine is responsible for the flourishing of the lobster.

What might be too warm for cod could still be optimum for lobsters. Hot and cold are relative, the article about the lobsters provides no data or cites to studies. Gulf of Maine temps warmed too much for cod, the lobsters usual range south of the Gulf of Maine warmed too much for them, they moved north.
4.6 / 5 (10) Oct 30, 2015

Considering your career, one I envy having spent my teens in Mission Beach and time in the labs at Scripps I can appreciate your frustration.

Having said that, the article in PO and other news outlets was intended for the general public, not for those us that have more than a passing interest in the subject. Would I have preferred more detail? Of course I would and it was frustrating PO's link was broken but I knew I would
find the study and happily it was open access.
1.7 / 5 (6) Oct 30, 2015
Additionally, the temperature increases were in hundredth of degrees and recorded over a period when satellite temperature measurements used were far below the daily variations and were not capable of accuracy within the ranges discussed in the study. I suggest you look into the host of satellite data gathering accuracy problems (totally ignored by the climate community - both extremes) not just in sea temperatures, atmospheric temperatures and altimetry (sea level rise - satellite date differs significantly from surface gauge measurements). I have a hard time resolving the assertions made from climate data that exceeds the respective technologies accuracy limitations and as antig points out by example.

Here are a few links:

2 / 5 (4) Oct 30, 2015
Since the P.O site incompetently shortens comments less than what they show the limits here are the links below that were inserted above - with supposed space remaining.

I also you suggest we all review the science of metrology (not meteorology). Current agenda based science communities take broad abusive advantage of data manipulation violating the most basic metrology guide lines regarding accuracy precision.


3 / 5 (2) Oct 30, 2015
Thank you, Exxon
4.4 / 5 (7) Oct 30, 2015
This "study" claims the warming in the Gulf of Maine is responsible for the collapse of the cod, the other claims the COLD waters in the Gulf of Maine is responsible for the flourishing of the lobster.

Goracle embarrasses himself again. From his lobster article - "largely in response to adverse environmental conditions, including increasing water temperatures over the last 15 years" and "It very much looks like what you would expect from a species that is responding to a warming ocean: It's going to move toward the poles" So the lobsters are moving north - from the warming waters of New England - and thus lobster populations further north are increasing. Totally in line with the content of the article published by Physorg.
2 / 5 (4) Oct 30, 2015
Greenonions - your theory and most of the mobile species responses to warming ocean pronouncements are denied by the species basic biology (including Cod) and their temperature tolerances. Homarus americanus ranges into the waters of North Carolina. A couple degree rise in average water temperatures in Maine will go unnoticed by the local lobster population. Inshore toxic chemical pollution on the other hand will not. The Bay Maine Cod fishery differs from most other Cod fisheries in that it is closer inshore and has less exchange than offshore fisheries - again pointing more to chemical pollutants than temperature increases. Come back with your theory when they find no H. americanus in the waters off N.C. and a when a broader and more precise examination of the Bay Maine water quality changes have been made. Until them I will file this as one more agenda driven "science" article. This doesn't mean there is no warming - it's just an unconvincing and poorly supported example.
1.8 / 5 (5) Oct 30, 2015
Additionally mobile species are poor indicators in general for environmental temperature changes - as are satellite measurements of the temperature of the skin of the ocean. When you have demonstrable precise water quality data and demonstrable changes in sessile species displacements, you can begin to question local temperature changes as a possible driver.
4.4 / 5 (7) Oct 30, 2015
Dug - which theory of mine are you referring to? I don't recall proposing any theory, just taking a couple of quotes out of the article that goracle referenced - that completely support the information in today's article. As usual - goracle links to references that he is not capable of comprehending - and thus he thinks they say things that they do not say. I do not share the disdain you have expressed for the science community - but as I often express on Physorg - this is not the forum to debate such issues in depth - 1,000 characters just doesn't cut it. I would love to see you have an exchange with the authors of this article regarding your disagreements - but I remain confident you will not do that.
5 / 5 (1) Oct 30, 2015
;vietvet thanks for reference. The AMO cycle is ~ 30 yrs. I wonder if there is a record of these gulf stream eddies having such a profound effect in the gulf of main before.
I also noticed that the el Nino temperature rate does not seem to be as 'red'. Perhaps all maps are 10 yr averages and el Ninos are usually short term 1-2 year events.

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