As temperatures warm and water cycle patterns change, nearly every living thing on the planet is on the move.
Off the U.S. East Coast between New Jersey and Maine, trawl surveys started by the National Marine Fisheries Service in the early 1960s provide one of the richest, longest-term datasets of environmental conditions and marine species abundance available anywhere. These datasets are showing that the waters of the northeast continental shelf, Georges Bank and the Gulf of Maine have been warming. As the waters warm, many fish and invertebrates have been moving northward or offshore into deeper waters.
As the fish move north, so do the fishermen.
The data on where fish are caught is more complicated to interpret than the trawl survey data on the fish themselves, due to changes in reporting requirements for fisheries. So as a starting point, Dr. Malin Pinsky, a fisheries scientist at Princeton who will be working at Rutgers starting later this summer, and Dr. Michael Fogarty, who leads the ecosystem assessment group at NOAA’s Northeast Fisheries Science Center, analyzed records of fisheries landings by state, and calculated the mean latitude of the fishery, weighted by biomass of landings and by value during each year for the last five decades.
Pinsky created quite a stir when he presented this research at the nation’s major fisheries management conference in Washington D.C. this spring, which showed, for the first time, a statistically significant northward trend in key fisheries since the 1960s.
Pinsky and Fogarty focused their study on four species that had been shown to have northward shifting populations: lobster (Homarus americanus), yellowtail flounder (Limanda ferruginea), summer flounder (Paralichthys dentatus) and red hake (Urophycis chuss). All four are commercially important and represent a range of life history patterns (e.g. lobsters and yellowtail flounder are more sedentary, while summer flounder and red hake undertake longer seasonal migrations.)
The results were clear. The four species shifted northward at an average of between 16 and 48 miles per decade over the 50 years of data. So these species are now found, on average, 75 to 250 miles farther north than they were in the 1960s. The fishery for each species also shifted northward, but at slower rates, between 2 and 6 miles per decade, moving only 10 to 30 miles northward in the same period.
Dr. Pinsky puts this work in context: “What we found, for the first time, is that the social and economic benefits of fisheries targeting specific species are also moving north.” But, their results also picked up an important pattern: the fisheries for these four species are moving north less quickly than the fish.
Red hake provides a case in point for the role that fisheries regulations play in creating a slower poleward movement for the fishery compared to the fish. While the biomass of red hake has moved signficanlty northward since the 1960s, the fishery shifted northward from New York and Connecticut in the 1970s to Rhode Island in the 1980s, but has not shifted to Massachusetts and Maine since. Fisheries managers cited in Pinsky’s study attribute this halt in northward shift in fishery landings to regulations prohibiting the small-mesh gear in large parts of the Gulf of Maine.åÊ In an interesting twist, this lack of fishing pressure in the species’ newly expanded northern range may have contributed to its overall healthy stock status‰ÛÓand the northerly shift in the population’s biomass.
Pinsky emphasizes that these types of feedback loops—in how fisheries respond to fish, and then fish respond to fishery changes—have already likely played an important role for some species (like red hake) and should be considered in the future.
These patterns raise a slew of questions: How quickly will fished species shift in coming decades? How will fisheries communities cope? Will fishermen move? Will they change what they are fishing on? And how will the changes in fisheries feedback to influence the populations of marine species on the move?
Pinsky and Fogarty cite an example from across the pond that highlights the clash between individual motivations of fishermen in southern regions to catch the last of the “trailing edge” as it heads north, and the overall societal benefit to the more northerly fishery of allowing the species to establish and support an economically viable fishery to the north:
“The ‘Mackerel Wars’ in 2010 demonstrated this problem quite vividly: Icelandic fishermen began fishing a northward-shifting mackerel population while British fishermen resisted a reduction in their fishing quotas, thereby jointly threatening to overfish the population (Anonymous 2010).”
In coming decades, fisheries in the Gulf of Maine will face a set of new challenges and opportunities—some species are already moving into the region, like blue crabs, while the environment will likely become inhospitable for others, including potentially cod and lobster. Our relations with our neighbors to the south and north—and negotiations about who can target the leading edge and trailing edge of these populations—will help determine the future of our fisheries.
Fathoming is made possible by funds from Maine Sea Grant. Heather Deese holds a doctorate in oceanography and is the Island Institute’s vice-president of programs. Catherine Schmitt is communications coordinator for Maine Sea Grant.