Crustacean delicacy from subarctic waters

Queen crabThe ice-cold northern seas are not only the home of king crab (Paralithodes camtschaticus), but also of queen crab, also known as snow crab (Chionoecetes opilio). The snow white meat of the long spiderlike legs has an intense, slightly salty yet delicate flavour. The queen crab fishery is sustainable, and annual landings add up to well over 110,000 tonnes.

The names of fine crustacean species – both trade names and vernacular names – are often mixed up. Crawfish are often called lobsters, there is considerable confusion over prawns and shrimps, and the name queen crab is used for various different species. It is, for example in common use for the Australian giant crab Pseudocarcinus gigas. Carpilius corallinus, which lives in the shallow water from the Bahamas to Brazil or the Chilean snow crab Paralomis granulosa appear in trade as queen crabs. The crab species we are talking about here, however, lives in the ice-cold waters of the North Pacific and Atlantic and is called both queen crab and snow crab, Northern Arctic crab or spider crab. It is also regionally called “opilio crab”, derived from its scientific name Chionoecetes opilio (Greek chion – snow, oiketes – dweller, Latin opilio – shepherd or goatherd). With that, the identity of this crab species would probably be sufficiently clear were it not for a number of marketing strategists’ from some crab suppliers adding to the confusion. For alongside “genuine” opilio queen crabs the species Chionoecetes also includes three further species that are landed by commercial fisheries: C. bairdi, C. tanneri and C. japonica. These species, too, are mostly offered for sale as queen or snow crabs so that these names are rather to be understood as “generic trade names”.

Irrespective of this aspect, opilio queen or snow crab is the most widely spread, most frequently fished and commercially most significant of all the Chionoecetes crabs. The species is a typical benthic species that is found on soft muddy beds or loose sandy sediments in the shelf regions and upper edge of the continental slopes. Its habitat is the subarctic waters where temperatures rarely exceed 5°C over the course of the year. In the North West Atlantic the crabs are usually caught at depths of between 70 and 300 metres, in the North Pacific individual crabs have been located at 1,200 m. The main distribution area of queen crab covers the western Atlantic from Greenland via Newfoundland to the Gulf of Maine and the Arctic waters in the North Pacific from Alaska and North Siberia as far as the Aleutians, along from Kamchatka as far as the deep sea off Japan and Korea. In the meantime the crab is spreading further and further in the North Atlantic. In 1996 examples were found for the first time in the Barents Sea and in 2003 off the Norwegian coast. The stock seems to be growing in this marine area as catches of gravid female crabs seem to indicate. Fisheries scientists therefore rate opilio as an invasive species which could cause considerable damages to the ecologically sensitive Arctic region. In contrast to king crab (P. camtschaticus), which was introduced in the Russian and Norwegian coastal areas by humans, queen crab made its own way there, presumably along the north coast of Siberia.


Clear differences to king crab

Queen crabs are easily distinguishable from their much more popular relatives, the king crabs. Both species can grow to considerable sizes but the king crabs reach much greater weights of 2 to 4 kilograms on average (a maximum of 15 kg is even possible). In contrast, queen crabs rarely weigh more than one kilogram. The differences in appearance are also striking. Both species have very long legs, the span of which can be anything up to two metres in the case of king crab, while queen crabs only measure about half of this, i.e. just under one metre. The legs of opilio are also noticeably more slender in relation to their length. The most obvious difference, however, is in the number of legs. King crabs have four pairs of legs of which the foremost are modified into claws with a pincer and a larger breaker claw. In contrast, queen crabs have five pairs of legs. The two front legs also have claws but the difference in size is not so marked. The rear pair of legs is unusually small and seems almost stunted.  The two species are similar with regard to the colouring of their bodies which is mostly a rather washed out brown shade, but the shell of king crabs is considerably tougher, harder and more prickly than that of the more delicate queen. The difference in size is also noticeable in the crab fishery. Fishing baskets are considered well filled when they contain 60 to 80 king crabs. To fill the basket to the same extent with queen carbs nearly 200 are necessary.

The king crab fishery has a long tradition and, according to FAO statistics, was already carried out off Russia and Japan during the 1950s. Queen crabs were originally only caught by chance as bycatch during trawling and the commercial fishery for this crab species did not begin until the mid-1960s in Canada. The USA and other states joined the fishery in the 1990s. As is the case in the lobster fishery the catch was almost without exception made using baited basket traps or pots. The fishing gear is mostly set out on the sea bed over night at depths of 50 to 600 metres and then hauled in the next morning. Canada is the most important fishing nation for queen crabs and nearly three quarters of world production are caught in the West Atlantic in the region off Newfoundland and Labrador, in the Gulf of St. Lawrence and in Fundy Bay or Nova Scotia. Fishing times vary regionally but the largest quantities are landed during the spring and summer months. In 2014, landings of Chionoecetes species amounted to 228,305 t according to the FAO and at least 128,504 t of this total were Ch. opilio. The actual yield of this species is probably much greater, however, for in the FAO statistics 77,974 appear only as Chionoecetes spp. and are not specifically separated into different species. The largest share of this quantity is presumably opilio.

Crab pots at Dutch Harbor on the island of Unalaska, as they are used for king and queen crabs (snow crabs).


Healthy stocks enable a sustainable fishery

Queen crab stocks between West Greenland and Canada are basically considered to be healthy although – as with all natural resources – natural fluctuations can occur independent of the fishery. Recently global climate changes are also having an impact on stocks. Although the stock has shown a tendency to decrease in the northern regions the biomass used for fishing has remained largely stable because the growing stock in the south makes up for these losses. Stock developments are monitored and evaluated by the Canadian Science Advisory Secretariat. The management of the fishery is based on permitted catch volumes and annual fishing quotas, fishing effort controls, legal minimum landing size, stipulations on permissible mesh sizes and variably fixed fishing periods and regions. The fishermen who hold a crab fishing licence – about 4,500 in all – are allocated an individual fishing quota every year and they are only permitted to put out a defined number of pots. The minimum mesh size is currently 13.5 cm. Only male crabs with a shell width of at least 95 mm may be landed. Female and undersize crabs have to be gently returned to the sea. If more than 20 per cent of the catch in any region consists of soft-shell crabs that have just moulted the zone is closed to the fishery for the rest of the season.

The entire package of these measures has led to the Canadian queen crab stocks remaining at a high level for more than ten years, something which can also be seen in the stable landing volumes. In the opinion of a lot of scientists the weak cod stocks in the region also contribute to this development. This fish is considered to be the major predator of the young crustaceans. Nearly three quarters of the Canadian crabs are exported to the USA, which alongside China and Japan constitute the most important market for queen crabs.

In the USA, the second largest fishing nation, the fishing season in the Bering Sea and off Alaska usually lasts from January to March or April depending on the ice cover. The TV report “The Deadliest Catch” made the fishery for queen crab (which are called snow crabs here) widely known and describes vividly the life-threatening occupation in ice-cold, winter storms and metre high waves. Because the fishermen only have a narrow time window for their hunt for snow crabs – the fishing season usually begins on 15 January and ends when the fishing quota has been fished – the fishing vessels compete for the prize in a rigorous derby. Competition is exacerbated by the fact that the snow crab stocks off Alaska suddenly plummeted at the end of the 1990s and have not fully recovered to this day. Because the allocation of fishing quotas is based around the reduced stock biomass the fishery is still considered sustainable and reasonable. Even the Monterey Bay Aquarium seafood watch (known for its critical appraisal of fisheries) rates snow crabs from Alaska “Best Choice”, and similarly catches from the southern Gulf of St. Lawrence in Canada. Crabs from the other Canadian fishing grounds are rated a “Good Alternative”. The queen crab fishery of the Canadian province Newfoundland and Labrador has held certification according to MSC since 2013.

Development of landings of queen crab (Chionoecetes opilio) according to FAO statistics. The actual landings are higher because some of the Chionoecetes catches are not differentiated according to species.


Immediate processing guarantees the best product quality

After the pots have been hauled on board again the crabs that do not comply with the fishing regulations are first sorted out. Male crabs whose body shell exceeds the required minimum size are either kept live or placed in ice to maintain their freshness and quality. They are usually killed by hand as gently as possible. To achieve this one holds the crabs with both hands by the legs and splits their body on an axe-shaped cutting device with a quick powerful blow. This method means that the four legs remain connected to one another beneath the body shell (one of the legs is the small posterior leg). This typical and probably most frequent crab product is called “cluster”. After the subsequent size and quality sorting the clusters are boiled in water until they reach a core temperature of 85°C. In this form the clusters serve as starting material for a range of products. They are for example shock frozen and glazed as a whole or as individual legs. Some processors use cryogenic freezers which enable particularly high qualities. The best qualities are fully but not excessively glazed and have at most 10 per cent breakages (the thin frozen legs break very easily.) Common grades range from 3/5 oz (about 85/142 g), through 5/8 oz (142/266 g) to 8 up (over 226 g).

Individual crab legs are available whole, divided into sections between the joints, and with a split or scored shell which makes the removal of the crabmeat considerably easier (“Snap ‚n‘ Eat”). Separate claws (“Cocktail Claws”) and pure crabmeat are also part of the range of most suppliers. A common industrial standard is mixed “combo” packs that contain 80% body and 20% leg meat. Better qualities are mixed at a ratio of 60 to 40. Frozen combo packs in 5 lb blocks that are quite reasonably priced in comparison are often used in hotels and restaurants for salads, soups and other crustacean recipes. There are also smaller packs, however, that are designed for sale to retailers and for the final consumer. Frozen crabmeat is usually available at the retailer’s without any preservatives or other additives. Most meat is to be found in the legs and claws, with small quantities in the body shell. Because it is not easy to remove the meat this time-consuming task is mainly carried out by companies in Asia, mainly in China. The average meat yield in the case of Ch. opilio is about 17%. That is less than that of king crab or Dungeness crabs which can have as much as 25% yield.

A popular meal in North American seafood restaurants is crab legs in teh shell whose meat is removed and dipped in melted butter before eating.

Frozen products have a longer shelf-life and are very versatile

The shelf-life of frozen, cleanly glazed crab legs and leg pieces is about one year. After thawing the crabmeat should, however, be eaten within three days. Crabmeat keeps longest when tinned for canned products can be stored for up to three years. Because queen crab products are almost without exception first cooked and then frozen they can be eaten either cold after thawing or reheated. Pre-cooked products should not be cooked too long then, however, because the meat can otherwise dry out, and the consistency becomes tough, and loses flavour. Basically crabmeat is suitable for almost all preparation methods. It can be poached, baked, fried or sautéed, heated in the microwave and – with the necessary care – even grilled. Typical defects and quality losses that occur frequently in crustaceans such as king and queen crabs that live in the wild are above all dirty shells that might, for example, be contaminated with barnacles or remains of seaweed which look unattractive and reduce the usable portion of product weight. A slightly blue colouring of the meat is considered an indication of a product being undercooked, ice crystals that are stuck to the crabmeat are a sign of too slow freezing or the frozen product having been thawed again in between. A particularly frequent fault is the incorrect mixture of body and leg meat, i.e. differing from the declaration, and excessive share of breakage, that is then well above the permitted 10%.

The mildly aromatic, succulent, slightly sweet tasting meat of queen crab is considered almost everywhere as a real culinary experience. The muscle sections of the leg meat are coloured snow white on the inside and on the outside they are covered with a bright orange coloured surface. Whilst king crabs have a strong, full intense flavour the queen’s more tender meat is more subtle in flavour and differs above all from king crab on account of its fibrous structure. That is why it can be used in so many different ways in the kitchen – to the pleasure of restaurant chefs and cooks. The slightly sweet crabmeat fits very well with sour or fatty ingredients such as pineapple, apples or other fruit as well as nuts or avocado. Recommendations for preparation range from soups and salads, through omelettes and soufflés, to seafood bakes. During preparation one really only has to make sure that the meat is not too strongly heated because it then dries out. Queen crab meat is less expensive than king crab meat.

A typical crab product is clusters in which the legs remain linked at the shoulder joint (the picture shows king crab clusters).

In Asia people eat crabs directly from the shell both warm and cold. They are served with fruits or wasabi, with fiery salsa or mango curry sauce. The tender leg meat is also appreciated by sushi fans. In Canada and the USA clusters are found on restaurant menus, the meaty cocktail claws are popular for buffets. The shell is usually removed or broken open so that the meat can be easily removed. It is then eaten after dipping in a cocktail sauce or melted butter. In Spain queen crabs are enjoyed as a delicacy at Christmas and they sell well during Advent and are then eaten with family and friends. Because 100 grams of crabmeat only contain 1.2 grams fat their energy content is also relatively low: 90 kcal. That promises pleasure without remorse particularly since the cholesterol content at 55 mg/100 g crabmeat is not too high compared to other crustaceans.





Biological information on queen crab (snow crab), Chionoecetes opilio

Males are almost twice the size of females

Queen or snow crabs are crustaceans with a flat body typical of crabs and five pairs of spider-like legs (the front pair are claws). In order to be able to grow the animals shed their hard exterior shell from time to time. This process is called moulting. Young crabs moult several times a year, older animals only once a year. During moulting lost limbs can be replaced. When female crabs reach maturity they stop moulting and so stop growing. That is why they remain considerably smaller than the males. After moulting the new body shell is still relatively soft for some time. Such animals are then called “soft-shell crabs” or “white crabs”.

Queen crabs are reddish to brownish on the upper side and whitish-yellowish on the lower side (when heated the crabs turn the typical red colour). Calcium deposits give the thorny body shell (carapace) which is almost as wide as it is long a considerable hardness. The shell of male crabs can be up to 150 mm, that of females up to 90 mm in length. Males grow to a maximum weight of 1.35 kg (leg span up to 90 cm), females reach just under 0.5 kg and a leg span of just under 40 cm. A larger claw is a typical feature of male crabs. This develops at the start of maturity and is probably meant to attract the females.

Queen crabs feed mainly on bottom-dwelling invertebrates (e.g. crustaceans, mussels, brittlestars, polychaetes), occasionally also smaller fishes. Cannibalism has also been observed in juveniles.

Both sexes live separately and only make direct contact during the spawning season. During mating the males pass a seed package to the females which store it in their spermatheca which they use for several insemination processes.  Depending on their age the females lay between 12,000 and 160,000 eggs which they carry around with them under their bellies for about a year depending on temperature.

Only male queen crabs whose body shell exceeds the legally permitted minimum size of 95 mm may be landed. On average they take 7 to 9 years to reach this size. The maximum age of this crab species is said to be 14 to 16 years.