Underwater World

North American Lobster

Northwest Atlantic

At a glance | Vital stats | Curiosities | Closeup

At a glance

Lobsters are among the biggest and longest-living marine crustaceans, some reaching ages of up to 50 years. Today we tend to think of lobster as a delicacy, but in New England up to the 1890s it was actually a food for the poor because there was so much of it to be caught. First Nations people captured lobsters long before Europeans arrived in North America, but it wasn't until the early 19th century that lobsters became a real commercial product. In Canada, lobsters are now a staple of the fishery.

Vital stats

Scientific name:

Homarus americanus

Taxonomy:

Invertebrate

Region:

Northwest Atlantic

Curiosities

What colour is lobster blood? No colour at all, in fact. At least, until the lobster is cooked. After that, its blood turns into an opaque white gel that is flavourless and safe to eat.

Closeup

About the North American lobster

Many people picture lobsters as red, but in fact that's only their colour after they've been boiled. North American lobsters can range from green and blue to red and brown depending on their habitat.

North American lobsters are measured by the length of their shell, also known as the carapace. The largest North American lobster ever caught was found off the shores of Nova Scotia. It weighed 20 kg and its carapace was over 27cm long. From the tip of its tail to the tip of its claws it measured more than 110 cm.

Lobsters' bodies are divided into three main parts: the claws, the body and the tail. Lobsters are members of the big family of crustaceans called decapods because they have 10 legs (‘deca' is Greek for 10). The claws on the two front legs each serve a different purpose: one is used for crushing and one for cutting. The other four pairs of legs are for walking. Lobsters rely on three pairs of antennas to sense their way around their environment. They have two compound eyes at the base of these antennas. Their eyes are very sensitive to movement—an advantage for lobsters as they try to avoid predators.

North American lobsters shed their shells as they grow in a process known as ‘moulting'. When a lobster outgrows its shell, the shell splits and the lobster crawls out. The lobster begins to form a new shell even before it sheds the old one. In the beginning, the new carapace is very soft. The lobster fills itself with water to make the hardening shell larger. After about a month, the new shell is as hard as the old one was.

Lobsters can moult four to five times in their first year; as they grow older, the process slows. Once females begin reproducing, they moult only about once every two to three years.

North American lobsters can be fished or harvested when they reach ‘commercial size'. Depending on where they live lobsters reach the necessary size—generally between 71 and 84 millimetres—when they are between six and 10 years of age. Most will have moulted between 15 and 20 times by then.

Lobsters move using their four pairs of walking legs and can travel relatively long distances. They use their tails to make short, quick movements when they feel threatened.

Lifecycle and reproduction

The reproductive cycle of a female North American lobster lasts about two years. Immediately after moulting, the female mates with a male and stores the sperm on the underside of her body in what is commonly called a sperm plug. Over the next 12 months she develops eggs internally. The next summer these eggs are extruded and fertilized with the stored sperm. The female then carries the eggs on her underside for nine to 12 months before they hatch. A female lobster will produce between a few thousand and several tens of thousands of eggs depending on her size. The survival rate of eggs is very low: of 10,000 young lobsters (larvae), on average only about one to 10 will become adults.

Lobsters are active hunters, feeding on a variety of animals, including crab, shellfish (mussels, clams and scallops), marine worms, gastropods (sea snails and slugs), starfish, sea urchins and fish. They will also eat the remains of dead organisms (in other words, act as scavengers).

The underwater world of the North American lobster

North American lobsters live in the Atlantic Ocean, specifically the area between Cape Hatteras in North Carolina and the Strait of Belle Isle that separates Labrador and Newfoundland. In the U.S., these creatures are found in the greatest numbers in the Gulf of Maine; in Canada, the biggest populations are close to southwest Nova Scotia and in the southern part of the Gulf of St. Lawrence.

North American lobsters are found in waters ranging between –1.5 and 24 degrees Celsius. In summer they move to shallower waters to take advantage of warmer temperatures; in winter most retreat to more protected deeper waters to avoid ice, extreme cold and winter storms.

Adult North American lobsters are fished in waters up to 300 metres deep depending on the region (although some have been found in waters as deep as 750 metres). They tend to live on rocky areas where they can take shelter for security and shield themselves from daylight (they are largely nocturnal animals). However, they can also be found in areas with sand, gravel or mud bottoms.

Cod, cunners, flounder, sculpin, wolfish, ocean pout, monkfish and dogfish can all prey on lobsters. However, predators vary significantly by region. Adult lobsters are much less vulnerable to predators.

Fishing the North American lobster

Lobsters are caught in baited traps placed on the bottom of the sea. Most of the lobster fishery takes place in shallow waters of less than 40 metres, although it can be much deeper in some regions. In Canada, the fishery is most active in the Gulf of Maine, Bay of Fundy, Southern Gulf of St. Lawrence and coastal Nova Scotia. Lobster fishing is generally prohibited between July and the end of September except for in the Northumberland Strait (there the fishing season runs from August to October). Offshore fishing happens year round but there is generally little activity in August and September.

The inshore lobster fishery management regime is defined as an input control fishery: a strategy based on limiting fishing efforts. Fisheries and Oceans Canada issues a limited number of licenses for specific management areas. Each license has an associated fishing season and fixed trap allocations. Other conservation measures include minimum legal harvesting size and no retention of egg-bearing females. The offshore lobster fishery has the same size controls and limited entry as well as an upper limit on the catch referred to as Total Allowable Catch (TAC).

The lobster fishery has one of the longest histories of fisheries regulations in Canada. Many of the management measures in place today date back over a century; the first conservation measure (protection of egg-bearing females) was put in place in the early 1870s. Other measures such as minimum size limits have been in existence for several decades as well. Limits on licenses and the number of traps were introduced in the 1960s and in 1974. To conserve stock and increase egg production, a number of changes have been made to the commercial minimum legal sizes, and in some areas special protection has been given to larger lobsters over the last 30 years. However, changes over the past two decades to vessels, trap design and electronic equipment have significantly increased fishing efforts.

For more information on the North American lobster visit:

Revised: October 2009