Not to be confused with the Pacific white skate

Pacific white skate

The Pacific white skate is a species of skate, family Rajidae. It is one of the deepest-living of all skates, occurring at a depth of 800 to 2,938 m on the continental slope. It is native to the southeast Pacific Ocean from the Galapagos Islands to off Waldport, Oregon; an egg case and embryo has...

, Bathyraja spinosissima.

The bottlenose skate, spearnose skate, or white skate, Rostroraja alba, is a species of skate

Skate

Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. There are more than 200 described species in 27 genera. There are two subfamilies, Rajinae and Arhynchobatinae ....

 in the family Rajidae, and the sole member of its genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. It is a benthic fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 native to the coastal eastern Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

. Due to overfishing

Overfishing

Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....

, it has been depleted or extirpated in many parts of its former range in the northeastern Atlantic and the Mediterranean Sea

Mediterranean Sea

The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

, and is now endangered.

Distribution and habitat

The bottlenose skate is found along the coastlines of the eastern Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, from the southern British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

 to South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, including the Mediterranean, and extending into the southwestern Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 to Mozambique

Mozambique

Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...

. It is listed as occurring in the northwestern Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an seas, but no valid records exist for the northern areas of the northeast Atlantic. It is a benthic species of sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

y and detrital

Detritus

Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...

 bottoms, at depths of 40–400 m (exceptionally down to 500 m) from coastal regions to the upper continental slope. Du Buit (1974) reported that it is more prevalent in rocky habitats.

Description

Most bottlenose skates are 60–150 cm long, with maximum recorded lengths of 230 cm for males and 202 cm for females. The flattened, angular pectoral fin fisc is about 1.4–1.5 times as broad as long. The snout

Snout

The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...

 is broad-based, abruptly tapering to a protruding sharp point and covered with small, sharp thorns. There are 40–45 rows of teeth in the upper jaw. The juveniles have 1 thorn before and 0–1 thorns behind the eye

Eye

Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

s and three rows of large thorns on the tail, 10–16 on the midline and 7–17 on either side. The adults have about 6 thorns around the inner margin of the orbit and 16–30 mid-dorsal and 17–29 lateral thorns on the tail. The skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 is rough in adults except for a smooth patch in the center of the disc; the underside is prickly except for smooth patches on the snout. The young are entirely smooth, except for on the snout. Large juveniles and adults are greyish or bluish with or without numerous small white spots above, white below with brown to black disc margins. Hatchlings are plain reddish-brown above, often with blue spots, and white below with broad dusky disc margins.

Biology and ecology

The bottlenose skate is a benthic predator of bony fishes, other elasmobranchs, fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 offal

Offal

Offal , also called, especially in the United States, variety meats or organ meats, refers to the internal organs and entrails of a butchered animal. The word does not refer to a particular list of edible organs, which varies by culture and region, but includes most internal organs other than...

, crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s, shrimp

Shrimp

Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

s, mysids, octopus

Octopus

The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...

, and cuttlefish

Cuttlefish

Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda . Despite their name, cuttlefish are not fish but molluscs....

. Younger, smaller fish are usually found in shallower water. Like other skates, this species is oviparous, with females producing 55-156 ova per year after a gestation period

Gestation period

For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...

 of 15 months. The egg cases are oblong in shape, with stiff pointed horns at each corners and the larger horns flattened. They are deposited in sandy or muddy flats in the spring

Spring (season)

Spring is one of the four temperate seasons, the transition period between winter and summer. Spring and "springtime" refer to the season, and broadly to ideas of rebirth, renewal and regrowth. The specific definition of the exact timing of "spring" varies according to local climate, cultures and...

. The capsules measure 12.5-18.3 cm long and 10.0-13.9 cm wide. This species is estimated to mature at 130 cm for males and 120 cm for females.

Relationship to humans

In the 17th century, the bottlenose skate was prized by the French

French people

The French are a nation that share a common French culture and speak the French language as a mother tongue. Historically, the French population are descended from peoples of Celtic, Latin and Germanic origin, and are today a mixture of several ethnic groups...

 for food. Because of its large size and slow reproductive rate, the bottlenose skate is extremely vulnerable to exploitation by fisheries. Anecdotal data suggests that there has been a substantial decline in the abundance and geographical range of this species in the north Atlantic and Mediterranean. In the north Atlantic, populations of bottlenose skates have declined severely or disappeared from the Bay of Biscay

Bay of Biscay

The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...

 and the Irish Sea

Irish Sea

The Irish Sea separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man...

; there are no longer targeted fisheries in these regions due to localized population collapses in the 1960s. There are also no recent records of this species in the waters off the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, where it historically occurred. The bottlenose ray still persists along the coast of the Iberian Peninsula

Iberian Peninsula

The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...

, though the population data is uncertain due to confusion with the shagreen ray

Shagreen ray

The shagreen ray or fuller's ray, Leucoraja fullonica, is a species of skate in the family Rajidae. This ray is found in the eastern Atlantic Ocean, from Murmansk, Russia through Norway, southern Iceland, the Faroe Islands, the Celtic Sea, the northern North Sea and Skagerrak, to northern Morocco,...

 (Leucoraja fullonica) and the sandy ray (L. circularis).

In the Mediterranean, bottlenose skates of most size classes down to egg cases are taken as by-catch

By-catch

The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...

 in multi-species trawling

Trawling

Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....

 fisheries. Historically, it was caught frequently off the coasts of Tunisia

Tunisia

Tunisia , officially the Tunisian RepublicThe long name of Tunisia in other languages used in the country is: , is the northernmost country in Africa. It is a Maghreb country and is bordered by Algeria to the west, Libya to the southeast, and the Mediterranean Sea to the north and east. Its area...

 and Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

 in the 1970s and was described as more or less frequent in the northwestern Mediterranean from the 1950s to the 1970s. The MEDITS trawl surveys, begun in 1985 and carried out six times a year in four geographic regions, indicates that the bottlenose skate is now very rare in the Mediterranean and that it has been reduced to a small fraction of its former range. The Italian

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 National Group for Demersal Resource Evaluation (GRUND) survey captured this species infrequently in the Adriatic Sea

Adriatic Sea

The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...

. The species is assessed globally as Endangered in the IUCN Red List

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

, and Critically Endangered in the northeast Atlantic. However, its status will require re-evaluation once data from its African range is available. In 2010, Greenpeace International added the bottlenose skate to its Seafood Red List, which includes commonly marketed species that "have a very high risk of being sourced from unsustainable fisheries".