Unraveling the Mystery of Southern New England’s Cod
The Gulf of Maine and Georges Bank stocks are overfished, but a new puzzle has emerged in the past 10 years.
While the plight of Atlantic cod in the northeast is well known, the emergence of a fishery off southern New England has puzzled scientists, but delighted anglers.
These days, it’s common knowledge that Atlantic cod are in bad shape, and dramatically so. Based on 2019 stock assessments, both the Gulf of Maine and Georges Bank stocks continue to be overfished and the groundfish fishery north of Cape Cod has shifted to focus predominantly on haddock and pollock.
Head a bit south, however, and a different picture emerges. Over the past 10 or so years, cod have found a foothold in the waters offshore of Block Island. During the winter months, feeding aggregations have turned into spawning aggregations, and anglers travel from far and wide to sail aboard party and charter boats from Point Judith and Montauk in pursuit of the bright, white-bellied bounty. No, they aren’t the 40- and 50-pound steakers of old, but healthy market-sized fish, with enough in the 20-pound range—a noteworthy catch these days—to keep things interesting.
It’s a pleasant surprise for anglers, but a puzzle for fisheries scientists, especially given that the region from New Jersey to Rhode Island represents the southernmost range of cod anywhere in the Atlantic. As coastal waters warm, cod in these southern haunts should be especially vulnerable to climate change impacts, yet this fishery is hanging on and even strengthening. Adding to the confusion is the fact that federal fisheries trawl surveys rarely capture cod in this region, and that while cod in this area are managed as part of the Georges Bank spawning stock, the fishery here is doing better than in other parts of the management unit. New research is helping scientists and managers learn more about the dynamics of this southern cod abundance, and whether it represents a separate, self-sustaining population.
Accidental Research: Larval Cod in Narragansett Bay
“As an undergraduate at the University of New England in Maine, I learned that Gulf of Maine cod were in really rough shape due to a combination of overfishing and climate change,” explains Joe Langan, a PhD candidate at the University of Rhode Island’s Graduate School of Oceanography (URIGSO). Imagine his surprise, then, when upon beginning his PhD studies in 2015, he learned of a burgeoning local cod fishery that winter. “Party-boat anglers were limiting out, and with all of the herring inshore, some guys even caught cod from the beach. Fishermen were saying that it was the best fishing they’d seen since the 70s, but all I could think was, ‘This can’t be!””
Langan’s graduate research focused on winter flounder, but he just couldn’t get away from cod. “We were conducting larval surveys for winter flounder in Narragansett Bay, but kept catching cod larvae, all the way up toward the city limits of Providence.” The discovery prompted Langan and his colleagues to take a slight detour from winter flounder research and explore past years of survey and fishery data to better understand the life history and abundance of Rhode Island’s cod.
The team examined the catches of larval fish and trawl surveys conducted by Rhode Island’s Department of Environmental Management (RIDEM) and URIGSO. The larval surveys, done in Narragansett Bay, have taken place on and off since 2001, but elements of the trawl surveys, which take place in Rhode Island state waters and sample young-of-year (less than 8 inches), juvenile (8-15 inches), and adult (greater than 15 inches) cod, have occurred since the late 1950s, providing the research team with a rich dataset. The scientists then modeled how environmental conditions like temperature and rainfall might affect the abundance of cod. To understand how survey findings might relate to what fishermen are seeing on the water, the research team also examined recreational and commercial catch data from the area collected through the NOAA Fisheries Marine Recreational Information Program (MRIP) and NOAA’s Vessel Trip Report (VTR) Program.
Hard Data Meets Anecdote
Langan and his colleagues found that the abundance of young-of-year cod detected in the trawl survey began increasing in 2002. Moreover, they discovered that the number of young-of-year cod in a given year was a significant predictor of commercial and recreational fishery catches two years later—when those fish approached keeper size. For example, folks may remember the Rhode Island cod bonanza of 2011, which was preceded in 2009 by the highest young-of-year abundance ever detected since the RIDEM trawl survey’s inception in 1979. This suggests that the fish being caught come from juveniles in the same area, not adults migrating from elsewhere. In other words, what the research team found matches what fishermen have been seeing on the water over the last 20 years. “We don’t know exactly why they came back, but they certainly have, and all data sources bear that out,” Langan notes.
It wasn’t, however, just young-of-year cod that helped tell the story. “We’re seeing all stages of Atlantic cod off the coast of Rhode Island—larvae at first hatch, older larvae, young-of-year, juveniles, and adults. That’s pretty strong evidence that these southern New England fish likely represent their own spawning population,” Langan says. He notes there is evidence that some larvae found in the region could come from the western Gulf of Maine; however, given the presence of newly-hatched larvae in Narragansett Bay, the research team is confident that at least some reproduction is local.
Langan’s results, which suggest a self-sustaining southern New England cod stock, align with the findings of an ongoing cod stock structure research program led by NOAA Fisheries and Canada’s Department of Fisheries and Oceans, which has identified five distinct spawning stocks, including one in Southern New England. Indeed, it adds to an ever-growing body of research, which includes morphometrics (analyzing the relative shapes of fish), tagging, and genetics, further indicating that Southern New England’s cod may be distinct. How to reconcile this new research with the current two-stock management of Atlantic cod (Gulf of Maine and Georges Bank) remains to be seen.
The story that Langan’s research revealed for southern New England’s cod was not all rosy. “We detected a strong negative correlation between the bottom temperature in February and the abundance of young-of-year cod,” he says—in other words, the warmer the temperature, the fewer young cod. And six of the 10 warmest Februarys ever recorded by the URIGSO trawl survey have occurred since 2002, the year that cod numbers started to increase. As waters continue to warm, adult cod may have a tougher time too, due to a combination of inhospitably warm temperatures in the fall and the increased local abundance of competitors like black sea bass.
For now, however, cod appear to be hanging on in the region, providing a ray of hope for this beleaguered species and an opportunity for managers to reconsider the assumptions used in an effort to conserve and rebuild cod stocks in a warming ocean.
8 on “Unraveling the Mystery of Southern New England’s Cod”
So if fishing is good when will the fish nazies close it down. I fish cape cod Bay and the codfishing is pretty good although you can’t harvest them. And for reasons unknown they throw you a 1 fish limit in September. Why bother. Ad the April bonus was just stupid. How many people launch early? They will never get it right.
Dont bother complaining about the regulations, the problem is water temperature. No cold water no cod to regulate. Climate change is real, any attempt to deny its a problem is perpetuating the root cause of cold water species stock collapses.
The Bay oh the bay, the way the rich spray weeds away. Rain runoff pesticides…..cite “the blob” last years lobster populations suffered from bottom h2o lacking adequate oxygen. It’s not just water temp IT IS US.
eric van helsing
Wonder how much the ocean has warmed 2oo feet down? The referenced temperature studies from NOAA are all surface water. I think that there are other factors at play…like the 40,000 seals on Cape Cod…let’s see 40,000 seals x 5 lbs of fish per week x 52 weeks equals over 10 million pounds of fish per year… cod? stripers? Wonder why there is a problem?
The old New England saying that “you can walk to England on the backs of Cod” is long dead, and self-inflicted. We have SO mismanged this fishery because of greed and money, and the very mistaken belief that it’s a resouce that we can take endless advantage of. the Gloucester fleet is LONG dead because of this greed, the large factory boats taking all they could, draggers damaging the bottom, we deserve all the misfortune we now have, WE caused it! It’s Cause and Effect. It wasn’t enough to shoot ourselves in the proverbial foot, no, we strapped a high-powered scope on the rifle to insure we’d blow that foot clean off!
eric van helsing
So the question is how do you bring it back? The almost complete shut down is not really having that big of an impact. The enviros dismiss this to global warming…yet a cod population is thriving in an area warmer than the gulf of maine….so the “warm water”theory doesn’t hold. The only true impact on cod population is seals and mismanagement. The cod of Norway and Iceland are fished heavier than in the Gulf of Maine and they support healthy population of Cod. Perhaps NOAA needs to look to their model of management because it is very different and appears to be working while our model is clearly not……
As long as fools believe and focus studies on “climate change” , actual ecological assistance can be ignored. Cod populations have increased and decreased in areas because of transitory sea water temperatures. This has been true for 20 million years. Get your minds out of the political mud and focus. Cod was so severely overfished , and still is, that it is in danger. Stop allowing fishing in large areas, stop commercial fishermen from taking the larger cod. Reseed depleted areas with adult cod over 20 pounds. Large cod eat the predators of cod eggs and codling. You need to bring in adult cod to prepare the environment. Instead you are allowing adults to be harvested. You need to learn what we had to about Marlin in Hawaii…..the bigger the fish…the stronger the fishery. More roe, less predators.
I agree. Leave the big fish to live and breed
Put them back in the water To breed
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