Smarter Living: Shopping Wise

lobsters

Photo: Keven Law/Flickr

“Lobsters are basically giant sea-insects,” wrote David Foster Wallace in his Gourmet magazine essay “Consider the Lobster.” Holdouts from the Jurassic period, lobsters are “biologically so much older than mammalia,” Wallace points out, “they might as well be from another planet.”

After surviving this planet’s tumultuous geologic and climatic transformations over the past 150 million years, the American lobster, or Homarus americanus, now faces a host of modern environmental hazards—over-fishing, pollutants, and, increasingly, warmer sea temperatures—in parts of its habitat stretching from the coast of Newfoundland and Labrador in Canada down to North Carolina.

In the late 1990s, large numbers of lobsters began to die off in the waters between Buzzards Bay, Massachusetts and Long Island Sound. Lobster numbers continued to drop precipitously before reaching a plateau of near record lows around 2003 for the reference period of 1984 to 2003. “There was a lot of mystery around [the die-offs],” stated NRDC Senior Scientist Lisa Suatoni, but scientists speculate a combination of shell disease and warmer water temperatures might be to blame.

Rising Temperatures

The inshore waters of southern New England have steadily warmed since 1999 alongside an increase in the numbers of days with water temperatures above 20° Celsius. According to a study by the Atlantic States Marine Fisheries Commission (ASMFC), prolonged exposure to waters warmer than 20° Celsius causes stress to respiratory and immune systems in lobsters, and leads to higher incidence of shell disease and acidosis (excessive amounts of acid in the blood). Scientists at Stony Brook University likewise found that higher temperatures have “profound deleterious effects on the physiology of lobsters” and suggest that warmer temperatures in the bottom layers of the Long Island Sound may in the long run render the area “inhospitable for lobster survival.”

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Indeed, lobsters—sensitive to even a 1ºC shift in temperature—are migrating away from warming waters in certain areas. In Massachusetts, lobsters appear to have left Buzzards Bay for the deeper and cooler waters just south in Vineyard Sound, a smaller area with a poorer oxygen supply and lower quality habitat. Here, lobsters congregate in higher numbers, leaving them more vulnerable to commercial fishing and forcing them to compete more vigorously for fewer resources. Egg clutches released by spawning females in these deeper waters may also be affected, as currents carry them away from areas where they traditionally settled into habitat less suitable for their survival.

Alkylphenols

While many scientists cite rising sea temperatures as a likely factor in lobster declines, warmer water may not be the only factor. Recent research from the University of Connecticut indicates that alkylphenol chemicals such as bisphenol-A leached from plastics and detergents into ocean waters, may increase lobsters’ susceptibility to shell disease. These chemicals, apparently ingested by lobsters from filter-feeding food sources like mollusks, may disrupt a lobster’s hormonal system and interfere with its development.

These chemicals may also cause lobsters to molt more slowly. During a molting stage, the shell of a lobster is thinner, leaving it more vulnerable to the bacteria that lead to shell disease. The symptoms of shell disease can range in severity, from shallow pits to ulcers that bore into a lobster’s shell, causing the shell to fuse to the membrane beneath. This advanced stage of the disease may prohibit a lobster from molting, which it must to do to grow and survive. In less severe cases, a lobster may molt prematurely to temporarily get rid of a diseased shell. And spawning female lobsters may be most at risk: while carrying eggs, these lobsters retain their shells for a lengthier period, allowing more time for bacteria to cause damage. Shell disease can weaken these females to the extent that they shed their shells before bringing their eggs to term.

Dropping pH

A third phenomenon, ocean acidification, may also impact lobster health. Acidification results from greater uptake of carbon dioxide by the world’s oceans as greenhouse gas emissions continue to rise. As carbon dioxide dissolves in water, it forms an acid, which eats away at calcium carbonate, the mineral produced by organisms to build coral reefs.  The rapid rate at which acidification is occurring, threatening coral reefs around the world, is a cause of great alarm to ocean scientists. However, acidification plays a murkier role in lobster disease. “The effect of ocean acidification on lobsters isn’t very well understood,” says Suatoni.

A controversial study conducted at Woods Hole indicates that some species, including the lobster, actually increase their ability to form shells in more acidic water. However, as Justin Ries, lead author of the Woods Hole study states in the magazine Oceanus, the energy consumption required to build shells in a lower pH environment for such species “may come at the expense of other critical life processes, such as tissue growth and reproduction.” Furthermore, the broad effect of acidification, despite variations in different species’ responses, “is to make it more difficult to build shells for anything that uses calcium carbonate,” says Suatoni. (Read more about acidification here.)

Doubts About Maine’s Boom

Not all is gloom and doom for the American lobster. In some areas, lobster numbers appear to be on the rise. A study published in the Canadian Journal of Fisheries and Aquatic Sciences in 2008, demonstrates that during the period of 1959 to 2005, communities of species inside Narragansett Bay and Rhode Island Sound increasingly shifted from vertebrates to invertebrates. Rising water temperatures in this area seem to have benefited the lobster and other crustacean species.

Additionally, lobster stocks off the coast of Maine are thriving. Catches in Maine have risen from 47 million pounds in 1997 to nearly 70 million pounds in 2008. Maine’s colder waters provide a buffer against higher temperatures; indeed, slight temperature increases—which foster a more rapid sexual maturation in lobsters—may have contributed to the boom in lobster populations in colder northern waters.

However, even Maine may be vulnerable to changes afoot. “Most of Maine’s fishery relies on lobster, it’s not a very diverse fishery,” says Suatoni. “And here we have two things coming down the pike that might harm lobsters: increased water temperature and decreased pH [increased acidification].” Carbon dioxide, it turns out, acidifies more quickly in cold water. “So Maine,” says Suatoni, “should be very concerned.” The success of Maine’s lobster industry may be, in the end, a type of bait and switch. “Everyone has a hard time believing things may get bad because things are so good,” says Suatoni. “That may be one interesting part of the story – there’s a kind of resistance to worrying about things around the corner.”

In David Foster Wallace’s words, perhaps it is time to consider the lobster.

Things You Can Do

  • Take care when shopping for lobster. Overall, the American lobster is a good but not an ideal choice, since humpback whales and endangered North Atlantic right whales sometimes get caught in lobster trap equipment. A better option might be the Spiny Lobster from the Florida, California and Baja fisheries—given “best choice” ratings by the Monterrey Bay Aquarium—particularly if you live closer to these fisheries. For more information about the sustainability of the American lobster as a food source, visit the Monterrey Bay Aquarium website.
  • Help reduce your CO2 emissions. Climate change affects global biodiversity. Reducing our emissions of CO2 is critical if we want to restore the health of the planet and enjoy small pleasures like a lobster dinner with our children and grandchildren. Learn more about how you can “lose ten tons of CO2” in 12 months and join the Smarter Living CO2 Smackdown. Steps you can take can range from something as simple as reducing the amount of beef and pork in your diet to sealing and insulating your home. Take a look.
  • Limit the amount of plastic in your life or choose plastics that are less harmful to you and the environment. Evidence indicates that certain chemicals that leach out of plastics, such as bisphenol-A and phthalates, impact not only wildlife but human health as well. Learn more about managing plastics with frequently asked questions about plastics and advice on recycling plastic packaging.

last revised 8/23/2011

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