The Lobster Life Cycle: From Egg to Adult

The lobster life cycle runs from a dark green egg glued under a female’s tail, through a few weeks as a drifting larva near the surface, to a hidden juvenile in a rocky crevice, and finally to an adult that may take five to ten years to grow up. Along the way a lobster survives long odds: by one Fisheries and Oceans Canada (DFO) estimate, only about 1 percent of floating larvae make it to the sea floor.

Here’s each stage in order, with Nova Scotia timing where we have it. For the wider biology of the species, see our guide to American lobster facts.

The lobster life cycle at a glance

Stage	What happens	How long (approximate)
Mating	Female mates in late summer, soon after she moults	A few days
Egg development inside the female	Eggs ripen in her ovaries; sperm is stored	About a year
Egg extrusion and brooding (“berried” female)	Eggs fertilized and carried under the tail	9 to 12 months
Hatching	Usually summer; June to September in Canadian waters	Varies with water temperature
Larvae (Stages I to III)	Drifting near the surface, feeding on plankton	Weeks, depending on temperature
Postlarva (Stage IV)	Looks like a tiny adult; dives to find shelter	Days to weeks
Juvenile	Lives in or near a shelter on the bottom	First 3 to 4 years mostly sheltered
Adult	Mature and able to breed	About 5 to 7 years to adulthood, varying with temperature

Sources: DFO (1988, 2011, 2013, 2022) and NOAA Fisheries. Ranges vary by source, as noted below.

How do lobsters reproduce?

Lobster reproduction is tied to the moult. DFO’s 2011 publication A Lobster’s life on the bottom describes males and females forming a bond before and during mating. The female moults in the male’s shelter, mates with him and stays a few days. Then she moves off on her own and eats heavily while her new shell hardens.

Why the timing? A female is only receptive for a short window. DFO’s 1988 Underwater World booklet says she is sexually receptive for only a few days after moulting, while her shell is still soft and flexible. Our article on lobster molting explains what that soft-shell stage involves.

According to DFO’s management plan for LFAs 27 to 38, the usual pattern goes like this:

1. Late summer: the mature female mates in her soft-shell condition immediately after moulting. The male transfers a sperm packet (spermatophore) into a seminal receptacle at the base of her tail.
2. The following year: her eggs develop in her ovaries. NOAA Fisheries notes that she can store the sperm for up to a year.
3. The next summer: she extrudes the mature eggs, fertilizes them as they pass the stored sperm, and attaches them to the swimmerets under her tail.
4. About a year later: the eggs hatch, usually in July or August in DFO’s Maritimes Region.

From mating to hatching, the whole process takes about two years. That’s why mature females usually produce eggs only every second year. DFO also notes that males need to be about the same size as females or larger for successful mating, and that too few large males can reduce mating success.

Big females play by slightly different rules. DFO reports that females larger than about 120 mm carapace length can spawn twice without moulting in between, sometimes fertilizing both broods with sperm from a single mating.

Lobster eggs: life as a “berried” female

A female carrying eggs is called berried, and her eggs are the dark green mass you see in the photo above. DFO describes them as about the size of a grain of rice, dark green and irregularly shaped.

How many? It depends on her size:

Female	Eggs carried
78 mm carapace (a large “canner”)	About 7,500
Typical large Bay of Fundy breeder	About 30,000
Jumbo over 125 mm	More than 40,000
Full range for the species	About 5,000 to more than 100,000

First three rows from DFO’s 1988 Underwater World booklet; the range is from NOAA Fisheries.

She carries them for a long time. Sources differ slightly on how long: DFO’s 2011 publication says 9 to 12 months, DFO’s management plan says 10 to 12 months, and NOAA says 9 to 11 months. Call it most of a year.

Because these females are the future of the fishery, the Atlantic Fishery Regulations say no one may buy, sell or possess a female lobster with eggs attached, so berried lobsters go back in the water. We explain why in berried female lobsters, and V-notching covers how fishers mark breeding females for extra protection. If you’ve ever found bright red “coral” inside a cooked female, that’s roe, covered in our article on tomalley and roe.

Hatching: when lobster eggs hatch in Nova Scotia

In Canadian waters, DFO says the eggs hatch between June and September, depending on water temperature. In the Maritimes the usual window is July or August. NOAA adds that egg-bearing females move inshore to hatch their eggs in late spring or early summer.

Newly hatched prelarvae stay attached to the female briefly. After a quick moult, Stage I larvae are released into the water column, within a few centimetres of the surface.

Lobster larvae: three stages in the plankton

This is the most dangerous part of a lobster’s life. DFO describes the larvae as transparent and about the size of a pea at first, growing to roughly thumbnail size by Stages II and III. They are weak swimmers, so wind and currents decide where they go.

DFO’s 2013 science assessment of southwest Nova Scotia lobster lays out the key facts:

• There are three larval stages followed by a postlarval stage (Stage IV).
• The larvae live mainly in surface waters but make a daily vertical migration.
• In the lab, Stages I to III take about 35 days at 12°C but only 22 days at 15°C.
• Development takes just 10 days at 22 to 24°C, but over 2 months at 10°C, and larvae need roughly 10 to 12°C to develop successfully to Stage IV.

DFO’s management plan sums the floating phase up as roughly 4 to 6 weeks. The larvae eat plankton, mainly cladocerans, copepods and crab larvae.

Survival is low. Larvae are eaten by larger zooplankton, jellyfish and comb jellies, and by fish such as mackerel and herring. DFO’s 1988 booklet estimated that only about 1 percent of floating larvae may settle on the ocean floor.

Settlement: a baby lobster finds the bottom

By Stage IV, the postlarva has the body shape of a tiny adult. DFO’s 1988 booklet puts it at about 15 mm long at this point. Halfway through Stage IV it leaves the surface and starts diving to search for shelter.

Where it lands matters enormously. DFO says postlarvae settle preferentially on bottoms that offer shelter, especially cobble. They have also been found in eelgrass and in hard clay or mud they can burrow into. The trip down is risky: shrimp, crabs, cunners, sculpins and even sea anemones prey on settling lobsters.

DFO has monitored lobster settlement at long-standing sites in the Bay of Fundy and, since 2005, at other locations along the Nova Scotia coast. Settlement density may one day be used as a reference point for managing the fishery.

Photo: Rick Wahle via Wikimedia Commons, CC BY 2.0. A juvenile lobster in cobble habitat in Rhode Island’s Narragansett Bay. This one has an unusual blue tint; read more in blue, yellow and split lobsters.

The juvenile years: hiding in the rocks

Once a young lobster finds a crevice, it stays put. DFO says lobsters remain in or near their shelter for their first three to four years to avoid predators such as sculpins, cunners, skates and crabs. At first they feed on small organisms in and around the shelter, including amphipods, small crabs and shellfish spat, and they may even filter plankton from the water.

As they grow, they spend more time outside the shelter, start foraging farther afield and move onto more varied bottoms, including open mud and sand. Young lobsters moult often: several times a year at first, slowing as they get bigger.

When do lobsters become adults?

DFO’s 2011 publication says lobsters reach adulthood within five to seven years, depending on water temperature. The range across Nova Scotia is wide:

• Warm water, early maturity. DFO’s 1988 booklet said Northumberland Strait females may mature at about 200 g, or three years old.
• Cold water, late maturity. The same booklet said Bay of Fundy females may not mature until about 700 g, or eight years old.
• Eastern Cape Breton. A study summarized by DFO in 2013 estimated the size at which half of females are mature at 71.5 to 75.8 mm carapace length at sites in eastern Cape Breton, lowest near Dingwall in LFA 27.

Those differences explain a lot about how each fishing area is managed. In a 2020 assessment, DFO noted that in LFAs 27 to 32 the minimum legal size is above the size of maturity, so most females caught have had a chance to breed first. In LFA 33 and other inshore fisheries, the median size in the catch is below the size of maturity, so a smaller share have bred. That’s why measures such as the minimum legal size and protections for egg-bearing females matter so much, and why the map of Nova Scotia’s lobster fishing areas has different rules in different places.

And then? The adult years

Adult lobsters live mostly alone in shelters and come out after sunset to feed. They keep moulting and growing, though less and less often. Females continue their two-year breeding cycle, and the biggest females, which can carry the most eggs, become especially valuable to the population.

How long can the cycle keep turning? DFO believes the maximum age is in the range of 50 years, though no one can yet age a lobster precisely. Read more in how long do lobsters live, or explore our lobster biology topic page.