The distribution of Atlantic mackerel is shifting north, east and into shallower waters in response to warming ocean temperatures and changing oceanographic and other environmental changes, a finding that may have significant implications for U.S. commercial and recreational mackerel fisheries, according to research from NOAA marine scientists.
Sensitive to changes in water temperature, Atlantic mackerel migrate long distances to feed and breed. Found in Atlantic waters from Cape Hatteras in the south to Newfoundland in the north, they play a central role in the marine food web, feeding primarily on small crustaceans and plankton while being preyed upon by a wide variety of species.
The overwintering population of the species' Northwest Atlantic stock has shifted from deeper waters off the continental shelf to shallower waters on the shelf where there is now a greater area in their preferred temperature range. In all, this population has shifted some 250 kilometers (~155 miles) north and about 50 kilometers (~30 miles) east between 1968-2008, according to researchers from NOAA's Northeast Fisheries Science Center (NEFSC).
"Our findings suggest that both the commercial and recreational Atlantic mackerel fisheries in the United States will probably be faced with more variable resource conditions in the future in terms of the winter distribution of the stock," study co-author Jon Hare said. "The continental shelf is warming, increasing the area over which the stock can be distributed, while at the same time the distribution of the stock is shifting northward."
There's plenty of Atlantic mackerel about at present to satisfy commercial and recreational fisheries, but the shift in population distribution is likely to make it more difficult to find and catch Atlantic mackerel during the traditional late winter-early spring season, according to the researchers, whose study is published online in the American Fisheries Society journal, "Marine and Coastal Fisheries: Dynamics, Management and Ecosystem Science."
US commercial fishermen may find it harder to locate large schools during the winter, when the majority of landings occur, because the mackerel are spread over a larger area within their preferred temperature range. Recreational mackerel fishing in the mid-Atlantic, which takes place in early spring, has been in a decline since the 1960s.
There has been a northward shift in the distribution of fish species associated with warming besides Atlantic mackerel in regional waters. Hare and co-authors William Overholtz and Charles Keith indicates that they are related to interannual variability in temperature and a general warming trend on the Northeast Atlantic continental shelf.
"Atlantic mackerel is one of many species shifting their distribution range as a result of changing oceanographic and environmental patterns," said Hare. "Those patterns include regional temperature changes from year to year and larger scale environmental forces or climate drivers such as the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO).
If the data from the late 1960s are indicative of the southernmost limit in the overwintering population of Atlantic mackerel, the change in the northern and eastern extent of the winter distribution of the stock is relatively large," Hare said. "Although there has been considerable inter-annual variability in the stock's distribution from the late 1960s through the first decade of the 21st century, the Atlantic mackerel stock has progressively moved from the offshore mid-Atlantic region to the southern New England shelf, and is now on the continental shelf more often in winter and much farther north and east of their previous winter positions, moving most recently onto Georges Bank."
- Global warming: Rising sea temps displacing fish populations (summitcountyvoice.com)
- Scientists link shifting Atlantic mackerel distribution to environmental factors, changing climate (eurekalert.org)
- Scientists link shifting Atlantic mackerel distribution to environmental factors, changing climate (physorg.com)