Language selection

Government of Canada / Gouvernement du Canada

Search

Snow Crab (Chionoecetes opilio)

On this page

Species overview

Physical description

Top view of a Snow Crab with claws. Refer to physical description.
Snow Crab (Chionoecetes opilio)

Snow Crab is a crustacean with a relatively small, round and flat body. It has 10 long, slender legs, with claws on the two front pairs, while the four back pairs are used for walking. Snow Crab shells can range in colour from light red to brown on top, and white to yellowish underneath. Parts of the shell can be iridescent, meaning they change colour when looked at from different angles.

The central body, called the carapace, of a male Snow Crab can grow to a maximum width of 150 millimetres with legs extending to almost 1 metre in length. Male Snow Crabs can weigh up to 1.4 kilograms, while females are about half the size of males with smaller claws and a rounded, flexible flap on their abdomen for carrying eggs. Snow Crab can live for up to 20 years.

Distribution

In eastern Canada, Snow Crab range from central Labrador in the north to western Nova Scotia in the south, and throughout the Gulf of St. Lawrence. Snow Crab prefer water temperatures below 3°C, but can tolerate temperatures up to 7°C. They live most often on sandy or muddy sea bottoms, at depths ranging from 20 to 2,000 m.

Life cycle

Close up of a male and female Snow Crab.
Comparison image showing male Snow Crab (top) female Snow Crab (bottom).

Snow Crab grow by periodically shedding a hard outer shell in a process called moulting. After moulting they have a softer shell for about 8 to 10 months. Snow Crab stop growing when they reach sexual maturity. Sexually mature males have slightly larger claws, and carapace widths ranging from 40 to 150 mm. Sexually mature females develop a wider abdomen for carrying eggs, and have carapace widths ranging from 40 to 95 mm.

After mating, female Snow Crab carry between 20,000 to 150,000 eggs under their abdomen for 1 to 2 years. Eggs hatch in late spring or early summer. Newly-hatched larvae spend 12 to 15 weeks in the water column before settling on the sea bottom. Sexually mature females may live for 5 to 6 years and produce a total of 2 to 3 groups of eggs in their lifetime.

Fishery history

Snow Crab landings in Atlantic Canada were first reported in the early 1960s as bycatch from groundfish draggers in the Southern Gulf of St. Lawrence. In 1965, a Danish seine fishery was started for Snow Crab off Cheticamp, Nova Scotia. The program expanded into New Brunswick and Prince Edward Island in 1966 and Quebec in 1967. The Snow Crab fishery in Newfoundland began in 1968 in Trinity Bay.

Two crab fishing vessels with traps loaded on the back.
Snow Crab traps loaded on board a fishing boat.
Two hauling a trap full of snow crab on board a fishing boat.
Hauling a trap full of Snow Crab on board a fishing boat.

By 1968, harvesters switched to baited traps. Approximately 60 boats participated in the fishery with fishing effort concentrated near Gaspé in Quebec, and in western Cape Breton, Nova Scotia. Snow Crab fishing in eastern Nova Scotia began in the late 1970s. Fishery development was slow until the 1980s when it began to expand rapidly to become one of the largest fisheries in Canada in terms of landings and economic value. In recent decades, the Newfoundland and Labrador fishery has been the largest, with rapid expansion occurring in the fishery following groundfish collapses in the early 1990s.

Snow Crab traps are conical and designed so that female crabs and male crabs smaller than the minimum legal size are able to freely move in and out. The conical traps used in the Snow Crab fishery are not considered to have major negative impacts on fish habitat.

Protocols are put in place to avoid excessive catch, as well as handling and discarding of soft-shelled crabs to allow them to continue to grow and mate. This can lead to closures in certain areas if soft-shell catches are too high.

The Snow Crab fishery in Atlantic Canada is comprised of First Nations and Indigenous groups, as well as offshore, mid-shore, and inshore commercial fleets that have access to approximately 60 Crab Fishing Areas (CFAs). CFA boundaries are not based on biological considerations and are solely for management purposes. The fishing season generally runs between April and September. During the fishing season, the fishery is subject to local area closures to limit impacts on soft-shelled crabs and North Atlantic right whales.

Southern Gulf of St. Lawrence
Map of Crab Fishing Areas used to manage Snow Crab in eastern Canada.
Crab Fishing Areas (CFAs) used to manage Snow Crab in eastern Canada. Image credit: Mikio Moryiasu.
Map of Crab Fishing Areas in the Southern Gulf of St. Lawrence Areas (12, 12E, 12F and 19) and geographic features.
Southern Gulf of St. Lawrence Crab Fishing Areas (12, 12E, 12F and 19) and geographic features.

The Southern Gulf of St. Lawrence Snow Crab fishery is comprised of First Nations and Indigenous groups, as well as mid-shore and inshore fleets from:

  • New Brunswick
  • Nova Scotia
  • Prince Edward Island
  • Quebec

Snow Crab in the Southern Gulf of St. Lawrence is treated as a single stock for assessment purposes. There are currently 4 CFAs in the Southern Gulf of St. Lawrence:

  • 12
  • 12E
  • 12F
  • 19

CFA 12 is the largest by area, number of participants and landings. The fishing seasons in CFAs 12, 12E and 12F generally start as soon as fishing grounds are clear of ice in April and close on June 30. In CFA 19, the fishing season starts in July and closes in September.

There are 2 buffer zones within the Southern Gulf of St. Lawrence where fishing is prohibited:

  • a 2 nautical mile-wide strip located along the northern edge of Area 19
  • along the south edge of Area 19

During the fishing season, the fishery is also subject to local area closures to limit impacts on soft-shelled crabs, as well as closures due to the detection of North Atlantic right whales in fishing grounds.

Newfoundland and Labrador

The first Snow Crab landings in Newfoundland occurred in the late 1960s as bycatch in the groundfish gillnet fisheries in Trinity Bay. During the 1970s, directed Snow Crab fisheries developed along the northeast coast, primarily in NAFO Division 3L, eventually spreading into 3K. Crab fishing occurred sporadically in NAFO sub-division 3Ps in the 1970s, but did not occur on a regular basis until the mid-1980s.

The fishery in Labrador (NAFO Division 2J) began in the mid-1980s. Small-scale exploratory fisheries started in 4R in the late 1980s, initially in Bay St. George and Bay of Islands, with the first significant landings occurring in the early 1990s.

Individuals who harvested Snow Crab in Newfoundland and Labrador prior to the expansion of the fishery in the 1980s were designated as full-time license holders in Division 2J, 3K and 3L. Initially, harvesters with full-time licenses operated in areas close to shore, but have since moved to harvest crab beyond 50 miles from land.

Supplementary fisheries were implemented in 2J, 3K, and 3Ps in 1985 and in 3L in 1987. These fisheries were developed to provide harvesters access to Snow Crab to supplement incomes negatively affected by declining groundfish resources.

Temporary seasonal Snow Crab permits were first issued to operators of vessels less than 35’ in length in 1995 in response to increasing Snow Crab resources and declining groundfish resources, on which enterprises had traditionally depended. In 2003, the Minister of Fisheries and Oceans announced the conversion of temporary seasonal Snow Crab permits to permanent inshore Snow Crab licenses.

Maritimes Region

The Maritimes Region Snow Crab fishery is comprised of First Nations and fishers from Nova Scotia. Three large crab fishing areas (CFAs) are assessed:

  • NENS (formerly CFAs 20-22)
  • SENS (formerly CFAs 23-24)
  • 4X (formerly CFA 24W)

The fishing seasons for NENS and SENS begin in early spring and end in the fall. The fishing seasons for CFA 4X begin in the fall and end in the spring of the following year.

CFA 4X and parts of the SENS represent the southernmost extremes of the distribution of snow crab in the Northwest Atlantic Ocean. These populations are exposed to the warmest and most variable environmental conditions.

Ecosystem context

Snow Crab eat invertebrates, such as:

Predators of Snow Crab include:

Small Snow Crabs are particularly vulnerable to predation, as are soft-shelled crab in the spring moulting season.

Climate change is impacting Snow Crab habitat. Some of the changes observed include:

As a cold water species, Snow Crab in the southern Gulf Region survive the warmer months by living in the cold intermediate water layer that forms in spring and persists through summer and fall. The size and temperature of the water layer depends largely on prevailing winds and temperature conditions during the previous winter. Warmer winter conditions have negative impacts on the size and quality of Snow Crab habitats within the cold intermediate water layer. Strong winds and storms can lead to short-term mixing of warm surface waters and the cold intermediate water layer, which results in jolts of warm water within Snow Crab habitat.

Diagram of the cold intermediate layer habitat used by Snow Crab in relation to coast and continental shelves
Diagram of the cold intermediate layer habitat used by Snow Crab in relation to coast and continental shelves.
Text version

This diagram presents a cross-sectional view of oceanic water layers and the habitat of snow crabs. It illustrates three main vertical layers of the ocean:

  • the warm surface layer
  • the cold intermediate layer
  • the warm deep-water layer

The warm surface layer, located at the top, is characterized by low density and higher temperature water. Beneath it lies the cold intermediate layer, which is denser and is subject to seasonal mixing—indicated by arrows showing water movement, mixing with the warm surface layer during winter. At the bottom is the warm deep-water layer, which is also dense but warmer than the intermediate layer. Snow crabs are shown inhabiting the sloped seabed within the water column of the cold intermediate layer.

Map of fishable snow crab habitat in Maritimes Region.
Map of fishable snow crab habitat in Maritimes Region. A probability scale indicates the likelihood of habitat across locations, based on bottom temperature conditions, depth and species composition.

A smaller and warmer cold intermediate layer means less available habitat for Snow Crab to take shelter during summer and fall. This can lead to increased disease, starvation and cannibalism. Warmer temperatures also place higher metabolic demands on Snow Crab, requiring individuals to consume more food. Changes in temperature can also affect Snow Crab:

The timing of egg hatching and the release of larvae may also become unsynchronized with the phytoplankton bloom on which larvae feed.

In the Maritimes Region, environmental variability is influenced by the Gulf Stream from the south and the Labrador Current from the north.

Ocean acidification, due to an increase in dissolved carbon dioxide in sea water, represents a possible risk to developing Snow Crab shells, especially for larvae and juveniles.

North Atlantic Right Whales

The North Atlantic right whale is listed as endangered under the Species at Risk Act. Its distribution overlaps with Snow Crab fishing grounds. Canada has a suite of fisheries measures and initiatives in place in Atlantic Canada and Quebec to reduce the risk of entanglements. To help protect whales, DFO is also working closely with the fishing industry, Indigenous groups, and other partners to make fishing gear safer.

Science advice and research

Science advice and research for Snow Crab

Integrated Fisheries Management Plan

Integrated Fisheries Management Plan for Snow Crab

Sources

Page details

Date modified: