Warming waters around Martha’s Vineyard have discouraged what once were abundant fish. Top fisheries scientists with the National Marine Fisheries Service recently released a report citing the dramatic influence changing climate has had on at least one of the fish that used to spend a lot of time in these waters: Atlantic mackerel.
Atlantic mackerel have shifted away from the Vineyard and now are found more east and northeast, according to the report.
Atlantic mackerel once were hugely abundant around the Vineyard. A few anglers still remember jigging for tinker mackerel in Menemsha Channel and bigger fish in Menemsha Bight in the late spring and summer. Others can remember when the fish was caught all around the Island. In more recent years, Atlantic mackerel are only seen in this area in spring, for about two weeks off Aquinnah.
Overfishing has often been the easy explanation for their decline in these waters. Not so, according to the report coauthored by Jon A. Hare, of the National Marine Fisheries Service. The fish have moved away and are now abundant somewhere else.
Atlantic mackerel are a slim, fast-moving migratory fish that swim in tight schools numbering in the thousands. One fish can weigh up to seven pounds. They are seen from as far south as Cape Hatteras to as far north as Newfoundland. Mackerel was once an important part of the Vineyard diet. The fish were readily available and affordable.
“Climate and weather patterns in New England are rapidly changing, as evidenced by long-term air and near shore and at-sea temperature records as well as increases in regional sea surface temperatures,” according to a paper published online in the American Fisheries Society journal Marine and Coastal Fisheries: Dynamics, Management and Ecosystem Science. Using catch data and ocean sampling going back to 1968, the fisheries scientists say that Atlantic mackerel’s winter distribution has shifted 155 miles to the north and 30 miles to the east. The fish have also shifted to a larger area on the continental shelf.
The broad conclusion is not entirely new. Only a few years ago, National Marine Fisheries scientists reported that there were significant shifts in the location of a number of fish off the New England seaboard due to warming water temperature. What makes this report so significant is that scientists focused their interest only on mackerel for this report.
Mackerel are a highly migratory fish and sensitive to water temperature. The findings of the report also give a clearer picture of some of the effect water temperature is having on other local fish.
Mr. Hare, 45, an oceanographer and fisheries specialist with the northeast center in Woods Hole, who co-authored the paper with others, said the research project took two years to complete and is based on data already gathered going back 60 years. They used survey data on fish abundance and then did an overlay of water temperatures and found that water temperature moves the fish.
Mackerel prefer water temperatures from 41 to 55 degrees Fahrenheit.
“Water temperature is very important for aspects of biology. It controls metabolism and growth rates. As humans we respond similarly. If it is too cold, we put a coat on. If it is too warm, we can go swimming. Temperature can have a lethal effect too. At some point, the temperature is too warm, at some point the temperature is too cold,” Mr. Hare said. When mackerel are too warm, they move to cooler water.
In the past, the data has been used primarily to assess the population and well-being of the stocks out there, to see whether the stocks are abundant. This is a study that takes into account not only the numbers of the fish, but where the concentrations were centered, and it was tied to water temperature. Depending on the winter weather year to year, the scientists found that the fish responded: “In cold years Atlantic mackerel are closer to Cape Hatteras, while in warmer years they are farther north.”
With this kind of data pointing to global warming, Mr. Hare said there is plenty of room for more scientific study about mackerel. “One thing that still bugs us is that, while we see a relationship between general temperature changes in the North Atlantic, the exact mechanism that controls the distribution of mackerel is unresolved. Mackerel migrate. Temperature is important, but there is another mechanism,” he said.
Studying temperature is relatively easy compared to other factors that control the movement of the fish, like availability of food. “We’d like to study the impact their predators and prey have but that is far more difficult,” Mr. Hare said.
David Pierce, a deputy director of the state Division of Marine Fisheries, is elated about the report. Mr. Pierce said: “I have been struggling with the Mid-Atlantic Council members [which oversees the management of Atlantic mackerel] over stock assessments. The assessments [on the fish numbers that are out there] have never quite matched what the fishermen have reported.
“The assessments say that the fish are abundant but the fishermen say they can’t find them. That response caused us to think that the stock assessment was lower than what we thought,” Mr. Pierce said. “This makes a compelling case that the fish distribution has changed.”
Mr. Pierce sees other changes in fish stocks that could align with the Atlantic mackerel case. “We have a problem with black sea bass. The fish used to be extremely abundant in the summer in the waters off New Jersey. They have shifted and are now up in Nantucket Sound,” he said.
Changing water temperature makes it even harder for fisheries scientists looking for data to understand fish abundance. “It is a real wild card for a lot of species. It is a monkey wrench thrown in, when we try and figure out abundance,” Mr. Pierce said. The mackerel study has “great implications” in understanding other species.
Before he ran his Vineyard Haven fish market, Louis Larsen used to work as a commercial fisherman out of Menemsha. He worked regularly with his father, Louis Larsen, on the dragger Mary Elizabeth. Mr. Larsen said he can recall 30 years ago when they were dragging in the waters south of Block Island.
“In two tows we netted 15,000 pounds of mackerel. The fish used to cloud the water, they were so thick,” Mr. Larsen said.
“Fishermen could count on catching plenty of them through the spring and summer,” Mr. Larsen said.
Cooper A. Gilkes 3rd went fishing for Atlantic mackerel off Aquinnah last spring. The season was short, just a few weeks, and then they were gone. Mr. Gilkes said years ago the fish was far more plentiful.
The Vineyard Gazette archives are full of stories of Atlantic mackerel being abundant in these waters. Joseph Chase Allen, the Wheelhouse Loafer, wrote for the Gazette in a column whose date has worn off in the clipping file: “‘Anybody under the sun with a grain of common sense can catch mackerel!’ So says the dry-salted brother of the tide. ‘All in the world you have to do is get a line and a jig, go out off the point or on the edge of the rip and drag it around.’”
From The New York Times of June 28, 1893: “Dateline: Cottage City, Mass. An immense school of mackerel has ‘struck’ into Vineyard Sound and since Monday the hook-in-line fishermen of the vicinity have shipped nearly $3,000 worth of No. 1 mackerel to New York Market, at an average price of 12 cents per fish.”
Mr. Hare said the study of Atlantic mackerel opens opportunity for understanding the whereabouts of other fish in this changing climate.
“I see a changing role in the scientific community,” Mr. Hare said. In studying fish of the sea, he added:
“We need to take a more holistic view. We need to look at climate. We need to look at the physical environment. We need to look at the prey and predators of mackerel. I see all the managers are starting to look in new directions.”