Nature Notes: Lobster
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By Ed Robinson
Let’s test your wildlife knowledge: what is the heaviest arthropod on Earth? Too obscure for you? Ok, what is the longest crustacean out of roughly forty thousand different species in the world? Still not sure? Well, I’m certain every reader will know which creature has the biggest financial impact on Maine’s economy. That’s right; it’s Homarus americanus, the American lobster.
One of the iconic foods of Maine, along with whoopie pies and blueberries, lobster has featured in man’s diet for a very long time. The travel logs of explorer Magellan noted the vast number of lobsters in New England waters and their fine taste. The genus name, Homarus, derives from the French word for lobster, “homard.” It is thought the French adapted the Old Norse word “humarr” after Viking raiders settled in their country around the year 1000 A.D. The earliest reference I found regarding lobsters as food was from 1493 B.C. in Egypt, although that was for the spiny lobster, not the wonderful clawed creature harvested off our shoreline. In 1967 a fossilized lobster claw was found on Nantucket dating back to the Ice Age, which ended roughly 9,000 years ago.
We know that American lobsters were once distributed as far south as the Carolinas, but today few lobsters are harvested commercially from New York waters and further south. This has caused concern that warming ocean temperatures are causing lobster die offs or migration, and the question becomes, what will happen in Maine, where 80 percent of US lobsters are now captured? Scientific studies are underway to determine the factors that impact lobsters in Casco Bay and beyond, looking at issues like predation, disease, over-harvesting and ocean water conditions such as temperature and acidity.
In recent years, as harvests for most marine species have been in decline, lobster harvests in Maine have been setting records for volume and total value. The 2017 Maine harvest came in at nearly 111 million pounds, the sixth highest ever, but 16 percent below the 2016 harvest. With an average boat price of $3.91 per pound, the value of the fishery was $433.8 million in 2017, ranked number four in the record books. Coming on the heels of surveys showing fewer juvenile lobsters in some study areas, the question on everyone’s mind is whether 2017 was an aberration or the beginning of a downward trend. With so many variables affecting the lobster harvest, it will take time and research over years to reach any definitive conclusions.
While the average adult lobster is less than a foot long and weighs roughly one and a half pounds, the species is capable of long life and tremendous size. The Guinness World Record lobster is a 44 pound monster caught off Nova Scotia. It is believed that the oldest lobsters may reach 100 years old, a long time when you consider the harsh environment in which they live. Maine has a maximum size limit of five inches for lobsters (measured with a metal gauge from the back of the eye socket to the back of the main shell, or carapace) so that the oldest specimens are allowed to live and breed as long as possible. Last year I released one hard shell lobster that probably topped eight pounds.
Lobsters look like they were assembled from spare parts, with many different segments making up the shell that runs from head to tail. Part of the invertebrate family, there is no spine. The outer shell gives the animal the structure needed for life. The head, or cephalon, carries sizable antennae, parts of which are covered by hairs that carry nerve cells used to detect odors in the water. Shorter antennules can judge water speed and odor, helping the lobster pinpoint where odors originate. Scientists have identified more than 400 different receptors on the antennules, allowing the lobster to discriminate among various species of clams and other food. The eyes are made from thousands of individual lenses, giving the lobster a sort of piecemeal vision. They don’t see much detail but can detect movement around them. An odd feature of the head is the presence of two bladders that are used to project urine several feet in front of the lobster, helpful in communicating with potential mates or enemies.
The middle section of the body is called the thorax and is covered by the hard shell. On the bottom are five sets of legs, with the front two carrying the large claws that separate our lobster from most others around the world. The “cutter” claw has razor sharp edges used to tear prey into morsels for eating. I am always very careful of these claws because they can slice a finger wide open in
an instant. The other claw is often called the “crusher” and it carries heavy duty nodules useful for holding and crushing prey. Just like humans, lobsters can be left or right handed. Unlike humans, if a claw or leg is broken off, the lobster can grow a new one, but it will take a few years.
Also in the thorax are the multiple jaws and mouths the lobster uses to chew and pass food into the first of three stomachs. These stomachs are able to grind and process food into fine particles for digestion, or pass solid waste through the intestines to the rectum at the base of the tail. The middle gut is the source of tomalley, that greenish bile and liver material that lobster eaters love or hate (studies have shown that tomalley often carries high concentrations of contaminants like dioxin, which are potentially harmful to humans). Two sets of legs equipped with small pincers at the end are used to move food from the big claws toward the mouthparts. The last two pairs of legs end in a point and are primarily used for walking forward. Studies have shown tagged lobsters moving up to ten miles from the point of release.
A lobster carries 20 pairs of gills, which are located on the sides of the thorax. You probably know them as cream colored feathery elements that are not particularly edible. Water enters through the gills, is passed to the head for the extraction of oxygen needed for the blood, and then water is passed back through the gills carrying waste products. The heart of a lobster, located between the stomachs and the carapace, is simpler in structure than ours, having a single chamber and several openings through which blood is passed back and forth. The heart beats up to 130 times per minute and is controlled by nerve impulses instead of heart muscles. Don’t expect to see red blood – the hemolymph, or lobster blood, is clear. When the lobster is cooked, this blood turns into a milky white material that looks a bit like congealed fat.
The abdomen, or tail, has six sections that are joined by soft tissue. This allows the tail to flex as needed for swimming. This is the lobster’s primary device for making a quick backward escape from trouble. On the first five sections behind the carapace you will find sets of swimmerets, which are used for gentle propulsion and holding eggs in development. The wide tail fins come last, with five large segments side by side.
Mating for lobsters might be complicated by their hard shells, but prior to shedding her shell, the female releases pheromones. This attracts local males, who fight to determine which one will breed with her. The male takes the female into his hiding spot among the rocks and watches over her until she molts. At the right moment, the male turns the female on her back and uses
the rigid first set of swimmerets behind his carapace to insert sperm into the female’s seminal receptacle. The female may carry this seed for more than one year until she is ready to fertilize her eggs. These eggs, from 5,000 to more than 100,000 in old females, are then released onto the underside of her tail, where they are held in place by the swimmerets. The eggs resemble raspberries in appearance, certainly the reason why some lobstermen say an egg-bearing female is “in berry.” During an incubation period up to 11 months, the female will clean her eggs and fan
them with water to provide oxygen and cooling. In our area, eggs are generally laid in mid-summer and hatch early the next summer. The female waves her tail to release the tiny larvae, which then rise to the surface of the ocean, sometimes resting on jellies or other slow moving creatures until they are large enough to settle back on the ocean floor. Studies have shown that a lobster may go through 25 molts over a period of six or seven years before it reaches the minimum three and one quarter inch size for legal harvest.
Lobsters thrive in cold waters near shore, where they hide among rocks and other bottom structure. Depending upon water temperatures, tidal currents and the availability of food, lobsters also may be found more than 40 miles out in waters up to 1,500 feet deep. Their lives are dictated by their needs for food and safety. Their primary foods are mussels and clams, along with fish, shrimp, crabs, sea urchins, brittle stars, marine worms and squid. In areas where there is active lobster fishing, studies have shown that lobsters gain up to 50 percent of their food value from the herring, menhaden and redfish used as bait.
Several bacterial and parasitic diseases can impact lobster health and populations. Paramoebiasis is caused by an amoeba, and may have killed huge numbers of lobsters in Long Island Sound during 1999. In recent years, Maine lobsters have been impacted by a bacteria causing epizootic shell disease, resulting in black lesions on the back of the carapace, lowering the market value of the lobster and sometimes killing it. I have seen estimates that this affects roughly one percent of lobsters in Maine. Other than man, predators of lobsters include flounder, cod, eels, crabs, harbor seals and bass. The seals are known to follow lobster boats around, trying to snag bait bags or lobsters for an easy meal.
While some states and provinces allow the harvest of lobsters via nets or diving, in Maine the only legal method is to use specialized traps or “pots.” Originally made from wood, today’s traps are made from plastic coated metal for durability and easier handling. The standard four foot long trap weighs about 40 pounds. Full length wooden runners on the bottom protect lobster legs from being damaged. Woven mesh entrances on either side allow lobsters to enter the “kitchen,” but as they move into the second and third sections of the trap (the “parlors”), it is a bit harder for them to exit (unless they are undersized). Video studies have shown that 10 percent of lobsters encountering a trap will enter, lured by the fish bait, but only six percent of those entering will be caught when the trap is hauled to the surface.
Maine’s government authorities work with the lobster industry to regulate fishing methods and legal size limits to ensure the long term health of this economically vital business. Commercial lobstermen may fish up to 800 traps, which must be marked with unique buoy colors and license numbers to prevent poaching. The use of marine electronics like GPS allows the marking and hauling of traps in low light or foggy conditions, but night fishing is not allowed. During June, July and August no fishing is allowed on Sundays. In popular waters sprinkled with buoys, it takes a great deal of concentration for lobstermen to haul their traps and reset them without causing major snarls and bad tempers.
Undersized and oversized lobsters must be returned alive to the water, along with females bearing eggs or with a V-notched tail indicating she was captured with eggs in the past few years. The penalties for taking illegal lobsters can be severe, with fines and/or loss of license a major risk for a family dependent upon this traditional way of life.
Lobsters are normally dark green or brown with bluish tints. Every year or two we see reports of unusually colored lobsters coming aboard. Blue lobsters are estimated to occur one in two million, with one caught near Portland in 2017. Yellow lobsters are more scarce, about one in 30 million, with one caught off Salem, Massachusetts in 2017. While there are other color variations such as calico and striped, the rarest lobster is an albino, rated at one in 100 million. Two of these stunning creatures were caught within a few days and a few miles of each other near Rockland, Maine in 2014. Many of these genetic oddities end up living out their days at the Maine State Aquarium in Boothbay Harbor.
Now we come to the best part: eating the catch. If you want to start a good argument in Maine, just mouth off about the best way to cook and eat a lobster. Hooo boy, I wouldn’t touch that one with a 15 foot gaff hook! Whether you bake, broil, steam, grill, saute or boil it, lobster is a treat that lures many thousands of tourists to our shores each summer. Cook it long enough for the shell to turn bright red, the result of chemical bonds breaking down to allow the red colorant astaxathin to show its stuff. Don’t overcook it or that lovely white meat will become tough and chewy. Lobster meat is low in cholesterol, saturated fat and calories (until you splash warm butter on it). The meat is a good source of protein and those omega-3 fatty acids we need to fight heart disease. Add in the amino acids, minerals and natural vitamins and you have a tasty health food that makes you feel good all over. Yet I am often surprised by how many Mainers just don’t eat lobster.
So get your bib, nutcrackers, pick, hammer, fork, knife, lemon, paper towels and whatever else you desire and settle down to eat one of nature’s great gifts. Please don’t waste the tasty meat in those small legs and the body. Make mine a steamed soft shell, no butter, all tender, moist and sweet. Hold the new potatoes, clams, sweet corn, salad and bread – I like my lobster hot!