It is officially summer in Maine and summer means tourists. Throngs of people come up here now that the weather is finally warm. And when people think of the Maine coast, they think of lobsters – colorful buoys floating on the surface of the water, traps stacked on the shores, and restaurants steaming up red hot bugs. Lobsters are even on our license plates. Having grown up in Missouri, I remember putting together a puzzle of the United States and putting the Maine piece in, way up in the corner, with a big picture of lobster on it.

Lobsters are worth a lot to the state of Maine. The estimated value of the Maine lobster fishery last year was $533.1 million. It is the state’s number one fishery and employs more than 6,000 harvesters. That’s a lot of traps catching a lot of lobster. In total last year, 130 million lbs. of lobster were landed in Maine.

Lobster fishing is a tradition that has been passed from generation to generation, the trap fishery dating back to 1850. So, if we’ve been catching lobster for that long, how are there still enough lobsters out there to keep the fishery going?

There are several elements in any fishery that are necessary to keep it productive – one of them is to keep it reproductive. In the lobster fishery, there are two practices that have helped to protect a sizable chunk of reproductive adults.

Females that produce eggs carry them on the outside of their bodies – thousands of tiny black eggs stuck like juicy blackberries to the underside of their tails, which make them readily identifiable as reproductive. A “berried” female, by law, has to be put back into the ocean to release those valuable baby-lobsters-to-be. She also gets marked with a v-shaped notch in one of her tail flippers so that, once she releases her eggs, she can still be identified by this “V-notch” as a reproductive female. This practice helps to preserve such a large portion of females that it has skewed the overall population of lobsters to be a female-dominated.

Another critical measure is the measure of a lobster. Lobsters must be at least 3.25 inches in carapace length (from the eye socket to the base of the tail), which lets the smaller lobsters get up to a marketable size. They must also be no bigger than 5-inches long, thus protecting a chunk of big “brood stock” lobsters in the population. This is important because the bigger the female, the more eggs she can produce, and likewise, with bigger males producing more sperm. This is true by nearly exponential levels. For example, a 1-lb. lobster produces 8,000 eggs whereas a 9-lb. female may produce more than 100,000 eggs.

All this is to say that there have been important conservation practices in place for many years that have helped to protect the lobster population. However, there are still myriad other factors that impact the next generation of lobsters growing up to market size.

In order to track these fledgling baby lobsters, scientists sample over 100 sites every year in the Gulf of Maine to estimate the number of larval lobsters out there. This survey, known as the American Lobster Settlement Index, was founded in 1989 by University of Maine marine scientist Rick Wahle. The ALSI can help to predict what the fishery will look like in the coming years.

So, how are things looking? Well, a little confusing . Wahle and his team have seen a decrease in late-stage larvae since about 2007, while at the same time harvest levels continue to break records and the population of berried females is still quite high.

From every 50,000 eggs only about two lobsters are expected to survive to legal size. There are many things that happen along the way – some eggs never hatch, and then those that do helplessly float around in the water column often providing a delicious meal for other sea creatures. Those that make it through the early larval stages need to be in just the right place once they are ready to settle to the bottom and if they aren’t, they won’t survive.

Oh, and the timing of when they hatch determines how long they will have in the warmer summer waters to grow. And, they need ample plankton to eat as they develop. When any one of these requirements is off, the chances of survival drop.

Two recent trends could explain why the larval levels have been lower in the past several years. One is that the teeny copepods that lobsters eat have been found in lower numbers. The other is that the number of critters that eat lobster larvae and their copepod food has been increasing. Wahle and his team presented these findings recently at the 11th International Conference and Workshop on Lobster Biology and Management in Portland at the beginning of June.

There’s your primer in lobster science. I should have forewarned you that I got my Master’s degree studying female lobster maturity. There is much being done to protect the lobster population – its value as a food source, as a state icon and draw for tourism, and a mainstay of coastal communities. But, there is still much to be learned about this strange population of bottom-dwelling creatures. You can learn more about this research at https://umaine.edu/wahlelab/