BUSINESS, ENVIRONMENT, MARINE
September 28, 2010
Fathoming: Maine fish and birds in hot water?
by Dr. Heather Deese and Catherine Schmitt
The weather this summer was beautiful. Sunny, warm, sunny. But the record-breaking temperatures—the fourth warmest summer on record nation-wide—also followed a warm winter and spring. The period from January to August 2010 was the warmest on record for the state of Maine and the Northeast U.S. region overall. This extended period of warmer-than-normal atmospheric conditions likely contributed to higher-than-normal water temperatures, which may in turn have contributed to record-high lobster catches, record-low herring catches, and record-low breeding success for Maine’s seabirds.
Fishermen have been saying since early spring that the water this year has been warm. Mark Lazarri, an environmental monitoring scientist with the Maine Department of Marine Resources (DMR), confirmed that daily temperature measurements in Boothbay Harbor indicated warmer-than-normal water in 2010, especially during March, April and July.
Unfortunately, it is harder to pin down how warm it was throughout Maine’s coastal waters. While temperature is measured and recorded at all six of the oceanographic buoys along the coast, neither the National Oceanic and Atmospheric Administration (NOAA) nor the regional ocean observing system (formerly GoMOOS, now NERACOOS) have the funding to carry out the kind of regular analyses that would provide the type of public updates we get for air temperature and other weather conditions.
Analysis of data from the NOAA buoy 12 nautical miles southeast of Portland (by the authors) does show that coastal water temperatures were between 2 and 5 degrees Celsius (3 to 9 degrees F) above the historical average during spring and early summer. So the data supports what everyone has been saying: the water is warm. But what does that mean for marine species and the fisheries they support?
Lobstermen took advantage of the fair weather in late winter and early spring to ready gear and start fishing early. The lobsters responded to the warmth with an early shed. Carl Wilson, lobster biologist at the Maine Department of Marine Resources, confirmed “the shed occurred a solid three to four weeks ahead of schedule for the entire coast,” in mid-June instead of early July. Wilson also notes that lobster catches appear to have been strong, with extremely high catch numbers in some areas. Dave Cousens, president of Maine Lobstermen’s Association, concurs, “We’re doing well this year, likely keeping pace or better than last year in most areas.” Cousens adds, “In some areas where catch rates are usually not that great, guys are catching a lot of lobsters, more than they have in a long time.” He theorizes that this pattern could be related to the unusually warm bottom water he and others have measured with thermometers on their traps. According to Wilson, the lobster fishery appears to be on track to exceed the record-breaking catch levels of 2009 and, because prices have remained strong compared to last year, 2010 could end with a high overall landed value.
This banner year for lobster has also been a good one for other shellfish. Dana Morse, marine extension associate with Maine Sea Grant and University of Maine Cooperative Extension, said that Maine oyster growers saw excellent growth this summer. “Lots of spawning happened, that otherwise might not, and there were some small mortalities that came with that, but nothing too bad.” He added that “rainfall closures have been minimal and red tide has not been as bad as predicted,” contributing to a good year for shellfish growers and harvesters.
Unfortunately, the warm conditions have not benefited all species. According to Rebecca Holberton, an avian biologist at the University of Maine, seabird breeding success was extremely poor this year, especially for puffins and razorbills. “Overall, it was the worst year for puffin productivity [breeding success] in the almost 20-year record at Machias Seal Island. Puffin, laughing gull and tern populations also did not fare well this year at Petit Manan Island.”
What does this have to do with temperature? Low breeding success can be related to a number of factors, including adult health, timing of breeding and food availability and type. Adults returning to Machias Seal Island this summer fed their chicks butterfish, Atlantic suary, shrimp, and other species not typically part of their diet, which usually consists of juvenile herring. Even razorbills, which can dive deep and generally have access to herring, did not deliver this prime feed to their chicks. In addition, adult pairs settled into breeding on Machias Seal later than usual, and the fledging time period for chicks lasted two weeks longer than expected. Chicks fledged at smaller body size and mass, which does not bode well for survival. While the direct connection between poor seabird productivity and water temperatures this year has not yet been established, Dr. Holberton notes that studies of seabirds throughout the world have consistently identified water temperature as a key determinant of breeding success and colony productivity.
Dr. Holberton is currently analyzing physiological data for puffins and razorbills in an effort to understand the factors that are impact adult survival, health and breeding success year to year, and learn more about how environmental conditions impact adult bird health, and ultimately species survival at Maine’s seabird islands.
It was not only the juvenile herring that were making themselves scarce this summer. The commercial catch of herring in the inshore Gulf of Maine was the lowest since record-keeping started in 1960, according to Matthew Cieri, fish biologist with Maine DMR. “The catch in the inshore area has been 22,000 to 23,000 metric tons in the past few years, and this year to date the fleet has only landed about 4,000 metric tons.” Cieri noted that, while warm water temperatures may have impacted herring distribution in the inshore areas, he has yet to see a statistical analysis establish a correlation between temperature and herring stock size or distribution. Fishermen report that they saw herring and couldn’t catch them, or else didn’t see any inshore. Catches on Georges Bank, by contrast, have been strong (See “Where are the herring?” September, 2010).
What will next year bring? It all depends on the weather… or the climate.
This article is made possible in part by funds from Maine Sea Grant and the Oak Foundation.
Heather Deese holds a doctorate in oceanography and is the Island Institute’s director of marine programs. Catherine Schmitt is communications coordinator for Maine Sea Grant.
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