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Sleepless over lobsters: Can our luck hold?

Posted Dec. 01, 2011, at 5:32 p.m.

The largest lobster recorded in the scientific literature was caught off Cape Cod in 1974 and weighed 42.5 pounds. This behemoth was a male who was probably 100 years old.

Large lobsters are essential to the health of the fishery, but we haven’t managed them that way. Current rules almost guarantee that we will never again see such a giant lobster. After decades of trust that the fishery was well managed and lobster landings could remain high despite heavy fishing, I’m worried.

A population can take only so many violations of nature’s rules for its survival, and nature’s rules for lobsters operate over a time scale of decades. Females lobster take about a decade to reach sexual maturity, just like human females (age at first menses for half of human girls worldwide is 10. That’s not when most or all are mature, just the earliest half.) Lobsters can then reproduce for many more decades and, unlike humans, can theoretically grow and reproduce indefinitely.

But fishing pressure is so intense that few lobsters reach maturity. Of the record 94.7 million pounds of lobster Maine landed in 2010, an estimated 95 percent had just molted into the minimum legal size of about a pound and a quarter — less than eight to ten years old.

Imagine a world in which 95 percent of eight-year-old humans are removed every year. It would still be possible to maintain the global population, but if some disaster or epidemic swept the planet, there would be little chance of recovery. That’s the situation with lobsters. Most have vanished by age eight. That leaves few to grow old with proven survival genes to pass to the next generation.

Older lobsters have survival know-how. They have evaded predators, including humans; they have survived harsh weather, disease and maybe pesticide floods and thermal stress. Large females are more fecund, carrying more, larger embryos, and they travel greater distances, thereby spreading their genes far and wide, resulting in a higher probability of success.

While a strong population can cope with an onslaught of natural and human-derived threats, a compromised population cannot. The collapse of the lobster fishery in southern New England is a warning to Maine and Canada: rising temperatures, pesticides and disease might have been survivable except that they were acting on a weakened population. The result was catastrophic. The same thing could happen here.

In an ideal world, lobstermen would land plenty of lobsters at a good price while leaving sufficient numbers on the bottom to keep the population fit by reproducing for many decades, as nature intended. Unfortunately, at minimum legal size, less than half the females are mature. As a result, few lobsters reproduce even once.

Females carrying embryos on their abdomens are protected, and that’s good. But when captured, they are V-notched to mark them as breeders. The mark is an open wound that increases susceptibility to disease and predation, with no evidence that notching helps either them or the fishery.

In my three decades of studying lobsters, I conclude that the biggest fishery management problem is how to keep the population balanced among young and old lobsters. Current management measures don’t ensure that future generations of fishermen will benefit from future lobster generations.

My view is that the only way to guard the Gulf of Maine fishery against a disastrous crash such as the one south of Cape Cod is to guarantee that at least a few centurions survive. Instead, Maine has loosened its lobster rules by condoning the harvesting of “oversized” lobsters.

Maine was a leader in lobster conservation, the first to outlaw taking lobsters with carapaces longer than five inches, or about 3.5 to 4 pounds. Although Maine lobstermen still may not harvest them and ground fishermen may not land them here, Maine recently passed a law that allows processors to purchase “oversized” lobsters from Canada and states that allow capture. This creates a market that will be sure to be filled at the expense of the lobster population.

The Gulf of Maine lobster fishery is surviving on luck. Will our luck hold despite this latest assault? I hope so, but the question is keeping me awake at night.

Diane F. Cowan of Friendship is executive director of the Lobster Conservancy.

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