66 Whiteblotched Skate Bathyraja maculata

ventral dorsal

egg case

Nuchal

Dorsal diagram showing thorns on disc. Diagnosis The only Alaska species maximum size is 91 mm long by 57 mm of Bathyraja with a distinct line on wide. the ventral surface separating the uniformly dark tail from the light body. Maximum Size 147 cm. Also distinguished by the following Range Bering Sea, Aleutian Islands; combination of characters: scapular, western Bering Sea to Japan. orbital, and mid-dorsal thorns absent; nuchal thorns present and strong; Depth 73-1,193 m. ventral surface of disc light to dusky, without denticles. Remarks The whiteblotched skate is In Alaska waters, the whiteblotched skate is common in the Aleutian Islands and found in the Gulf of Alaska, Aleutian Islands, and Denticles Strong, evenly covering on the Bering Sea continental slope. Bering Sea. dorsal surface; ventral surface smooth. Although it appears to be rare in the Gulf of Alaska, it has recently been Coloration Dorsal surface gray with whiteblotched skate has only nuchal recorded as far east as Clarence Strait white blotches; ventral surface blotchy thorns on the disc, while the Aleutian (J. Bizzarro, Pacific Shark Research gray, with dark border; underside of skate has nuchal, mid-dorsal, and Center, Moss Landing Marine tail dark, separated from lighter ventral scapular thorns. Laboratories, pers. comm., 25 July surface of body by distinct line. 2006). Reproduction Oviparous. Egg case Similar Species The whiteblotched small, covered with stringy fibers and skate may be vaguely similar in dorsal rows of slender conical spines ending coloration to the Aleutian skate, in one or more tips; keel thin, narrow; with light blotches on a generally byssal threads attached at mid-case gray background. However, the and on posterior horns. Egg case

Whiteblotched Skate Bathyraja maculata 67 68 Photos of Alaska Sharks

Brown Cat Shark = 25 cm

Basking Shark Salmon Shark

Blue Shark Thresher Shark

Spiny Dogfish

Pacific Sleeper Shark

Great White Shark = 1 m Bluntnose Sixgill Shark Illustrations of Teeth of Alaska Sharks

Spiny Dogfish Pacific Sleeper Shark Bluntnose Sixgill Shark Basking Shark

Brown Cat Shark Thresher Shark Blue Shark Salmon Shark Great White Shark

69 70 Photos of Alaska Skates (Dorsal View)

Big Aleutian Deepsea “Leopard Skate Skate Skate Skate”

Commander Roughshoulder Longnose Alaska Whiteblotched Skate Skate Skate Skate Skate

= 0.5 m Roughtail Whitebrow Bering Butterfly Mud Okhotsk Skate Skate Skate Skate Skate Skate Glossary Alar hooks Series of hook-shaped thorns on the dorsal surface near Dichotomous key A key for the identification of organisms based the lateral margins of the disc in male skates. on a series of choices between alternative characters.

Benthic At the bottom of a body of water. Dimorphic Occurring in two distinct forms.

Bifid Divided into two equal lobes or parts by a median cleft. Disc The body of a skate anterior to the cloaca, composed primarily of the head, visceral cavity, and expanded pectoral fins. Byssal threads Stringy fibers attached to the lateral edges and horns of egg cases of skates, sharks, and chimaeras. Egg case The leathery protective covering that envelops the developing embryo of chimaeras, skates, and some species of Case length Smallest distance from the anterior margin of the egg sharks; also known as an egg capsule or mermaid’s purse. case to the posterior margin, not including the horns. Elasmobranch One of the two major lineages of chondrichthyans, Case width Greatest distance between the two sides of the egg including all living sharks and rays. case, including the keels. Heterocercal A caudal fin in which the upper lobe is larger and Chondrichthyan A member of the class Chondrichthyes, which more elongate than the lower lobe. includes holocephalans and elasmobranchs. Holocephalan One of the two major lineages of chondrichthyans, Clasper A reproductive structure located along the posterior represented in the recent fauna only by chimaeras. margin of the pelvic fins in male sharks and skates; also on the head in chimaeras. Homocercal A caudal fin in which the upper and lower lobe are similar in size and shape. Cloaca The combined opening of the digestive and urogenital system. Horns Elongated extensions of egg cases, usually on all four corners, that taper or curl near the ends. Denticle The hooked, toothlike scales found on sharks and skates.

71 Glossary 72 Interdorsal thorns The one or two thorns on the dorsal surface of Ova Eggs. the tail between the two dorsal fins in skates. Oviparous A mode of reproduction in which the female deposits Keel Flattened extensions on the lateral edges of skate egg cases thick leathery egg cases, containing one to several embryos, directly that may extend onto the horns. onto the seafloor.

Malar hooks Series of hook-shaped thorns on the dorsal surface Pelagic Open waters of the sea. near the snout in males of some species of skates. Placental A form of viviparity in which the embryo is nourished Mid-dorsal thorns A series of thorns on the dorsal surface of a directly from the female through a placental tissue. skate along the midline posterior to the scapular thorns and anterior to the pelvis. Precaudal length In skates, the distance from the tip of the snout to the posterior margin of the cloaca. Morphological Having to do with general body form and structure. Pseudosiphon A short groove found near the distal tip of the Nuchal thorns A series of thorns on the dorsal surface of a skate clasper in some skates. along the midline posterior to the orbits and anterior to the scapular thorns. RACE database (also RACEbase) A resource survey database maintained by the NMFS Alaska Fisheries Science Center’s Resource Ocellus A round blotch or spot surrounded by a ring of pigment. Assessment and Conservation Engineering (RACE) Division in Seattle, Washington. Oophagous A form of viviparity in which embryos receive their nutrition from the consumption of additional nonviable ova Reticulations Lines forming a network. produced by the female. Serrate Notched or toothed on the edge. Opercle A cartilaginous flap covering the gills and associated structures in chimaeras. Spine A stiff, sharp fin ray found on the leading edge of the dorsal fins in the spiny dogfish; also see thorn. Orbital thorns Thorns along the medial rim of the orbit on the dorsal surface of a skate, highly variable in size. Scapular thorns Thorns on the dorsal surface of a skate on either side of the midline posterior to the head. Tail length In skates, the distance from the posterior margin of the Total midline thorns The sum of all thorns in the midline series, cloaca to the tip of the tail (also known as caudal length). including nuchal, mid-dorsal, tail, and interdorsal thorns.

Tail thorns In skates, a series of thorns on the dorsal midline of the Viviparous A mode of reproduction in which the young are born tail posterior to the pelvis and anterior to the dorsal fins. as free-swimming miniature adults after an extended period of development inside the female. Thorn An enlarged, conspicuous denticle on the dorsal surface of a skate; also commonly referred to as a spine. Yolk-sac viviparity A form of viviparity in which the developing embryos are completely dependent on the nutrition provided by a Total length The distance from the anterior-most tip of the snout yolk sac inside the female. to the posterior-most tip of the tail.

Glossary 73 74 Selected References Bigelow, H.B., and W.C. Schroeder. 1948. Sharks. In: Fishes of the Hamlett, W.C. (ed.). 2005. Reproductive biology and phylogeny western North Atlantic. Memoirs of the Sears Foundation for of Chondrichthyes: Sharks, batoids and chimaeras. Science Marine Research 1(1):59-546. Publishers, Inc., Enfield, New Hampshire. 562 pp.

Carrier, J.C., J.A. Musick, and M.R. Heithaus (eds.). 2004. Biology of Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Board Can. Bull. 180. sharks and their relatives. CRC Press, Boca Raton. 596 pp. 740 pp.

Castro, J.I. 1983. The sharks of North American waters. Texas A&M Ishihara, H., and R. Ishiyama. 1985. Two new North Pacific skates University Press, College Station. 180 pp. (Rajidae) and a revised key to Bathyraja in the area. Jpn. J. Ichthyol. 32:143-179. Compagno, L.J.V. 1984. FAO species catalogue. Vol. 4. Sharks of the world: An annotated and illustrated catalogue of shark species Larkins, H.A. 1964. Some epipelagic fishes of the North Pacific Ocean, known to date. Parts 1 and 2. FAO, Rome. 655 pp. Bering Sea, and Gulf of Alaska. Trans. Am. Fish. Soc. 93:286-290.

Compagno, L.J.V. 1999. Checklist of living elasmobranchs. In: Love, M.S., C.W. Mecklenburg, T.A. Mecklenburg, and L.K. W.C. Hamlett (ed.), Sharks, skates, and rays: The biology of Thorsteinson. 2005. Resource inventory of marine and estuarine elasmobranch fishes. Johns Hopkins University Press, Baltimore, fishes of the West Coast and Alaska: A checklist of North Pacific pp. 471-498. and Arctic Ocean species from Baja California to the Alaska- Yukon border. U.S. Geological Survey, Seattle. 276 pp. Ebert, D.A. 2003. Sharks, rays, and chimaeras of California. University of California Press, Berkeley. 284 pp. Mecklenburg, C.W., T.A. Mecklenburg, and L.K. Thorsteinson. 2002. Fishes of Alaska. American Fisheries Society, Bethesda. 1037 pp. Eschmeyer, W.N., E.S. Herald, and H. Hammann. 1983. A field guide to Pacific coast fishes of North America from the Gulf of Alaska to Musick, J.A., and R. Bonfil (eds.). 2004. Elasmobranch fisheries Baja California. Houghton Mifflin Co., Boston. 336 pp. management techniques. APEC Fisheries Working Group, Singapore. 370 pp. Hamlett, W.C. (ed.). 1999. Sharks, skates, and rays: The biology of elasmobranch fishes. Johns Hopkins University Press, Baltimore, 515 pp. Sheiko, B.A., and V.V. Fedorov. 2000. Class Cephalaspidomorphi: Wilimovsky, N.J. 1954. List of the fishes of Alaska. Stanford Ichthyol. Lampreys. Class Chondrichthyes: Cartilaginous fishes. Class Bull. 4:279-294. Holocephali: Chimaeras. Class Osteichthyes: Bony fishes. Chapter 1. In: Catalog of vertebrates of Kamchatka and adjacent waters. Wilson, D.E., and G.W. Hughes. 1978. The first record of the brown Kamchatsky Pechatny Dvor, Petropavlovsk-Kamchatsky, Russia, cat shark, Apristurus brunneus (Gilbert, 1891) from Alaskan waters. pp. 7-69. Syesis 11:283.

Stevenson, D.E., and J.W. Orr. 2005. New records of two deepwater Zorzi, G.D., and M.E. Anderson. 1988. Records of the deep-water skate species from the eastern Bering Sea. Northwestern skates Raja (Amblyraja) badia Garman, 1899, and Bathyraja Naturalist 86(2):71-81. abyssicola (Gilbert, 1896) in the eastern North Pacific, with a new key to California skates. California Department of Fish and Game Stevenson, D.E., J.W. Orr, G.R. Hoff, and J.D. McEachran. 2004. 74:87-105. Bathyraja mariposa: A new species of skate (Rajidae: Arhynchobatinae) from the Aleutian Islands. Copeia 2004(2):305-314.

Selected References 75 76 Photo Sources

Alopias vulpinus...... H. Wes Pratt (NMFS Northeast Fisheries Science Center) Amblyraja badia ...... G. Hoff (NMFS Alaska Fisheries Science Center) Apristurus brunneus ...... D. Stevenson (AFSC), UW 29664 (adult) Alopias vulpinus...... H. Wes Pratt (NMFS Northeast Fisheries Science Center) Amblyraja badia ...... G. Hoff (NMFS Alaska Fisheries Science Center) Apristurus brunneus...... D. Stevenson (AFSC), UW 29664 (adult); D. Stevenson (egg case) Bathyraja abyssicola ...... D. Stevenson (adults); G. Hoff (egg case) Bathyraja aleutica ...... G. Hoff Bathyraja interrupta ...... D. Stevenson (dorsal); G. Hoff (ventral, egg case) Bathyraja lindbergi ...... G. Hoff Bathyraja maculata ...... D. Stevenson (dorsal); G. Hoff (ventral, egg case) Bathyraja mariposa ...... G. Hoff (UW 47197) Bathyraja minispinosa ...... G. Hoff (dorsal, egg case); D. Stevenson (ventral) Bathyraja parmifera ...... G. Hoff Bathyraja sp. cf. parmifera...... J. Orr (AFSC) Bathyraja taranetzi ...... D. Stevenson (dorsal), UW 113189; J. Orr (ventral), UW 113189; G. Hoff (egg case) Bathyraja trachura ...... G. Hoff Bathyraja violacea ...... J. Orr (UW 113488, adults); A. Orlov (VNIRO; egg case) Carcharodon carcharias...... Greg Skomal (Massachusetts Marine Fisheries) Cetorhinus maximus ...... marinethemes.com/Saul Gonor Hexanchus griseus ...... Dan Kamikawa (NOAA Fisheries) Hydrolagus colliei ...... North Pacific Groundfish Observer Program archives (adults); D. Stevenson (egg case) Lamna ditropis ...... Ken Goldman (ADFG) Prionace glauca ...... H. Wes Pratt (NEFSC) Raja binoculata ...... D. Stevenson (dorsal); K. Maslenikov (ventral; NMFS AFSC); G. Hoff (egg case) Raja rhina...... K. Maslenikov (adults); G. Hoff (egg case) Somniosus pacificus ...... S. Kotwicki (AFSC) Squalus acanthias ...... R. Lauth (AFSC) Index to Common and Scientifiic Names

Alaska skate...... 44 Bering skate...... 48 Mud shark...... 22 Aleutian skate...... 50 Big skate...... 40 Mud skate...... 54 Alopias vulpinus...... 30 Black skate ...... 62 Okhotsk skate...... 52 Amblyraja badia ...... 38 Blue shark...... 32 Pacific sleeper shark...... 22 Apristurus brunneus...... 28 Bluntnose sixgill shark...... 24 Prionace glauca...... 32 Basking shark...... 26 Brown cat shark...... 28 Raja binoculata...... 40 Bathyraja abyssicola...... 58 Butterfly skate...... 56 Raja rhina...... 42 Bathyraja aleutica...... 50 Carcharodon carcharias...... 36 Roughshoulder skate...... 38 Bathyraja interrupta...... 48 Cetorhinus maximus...... 26 Roughtail skate...... 62 Bathyraja lindbergi...... 60 Chimaera...... 18 Salmon shark...... 34 Bathyraja maculata ...... 66 Commander skate...... 60 Sandpaper skate...... 48 Bathyraja mariposa ...... 56 Deepsea skate...... 58 Somniosus pacificus...... 22 Bathyraja minispinosa...... 64 Great white shark...... 36 Spiny dogfish...... 20 Bathyraja parmifera...... 44 Hexanchus griseus...... 24 Spotted ratfish...... 18 Bathyraja sp. cf. parmifera...... 46 Hydrolagus colliei ...... 18 Squalus acanthias...... 20 Bathyraja taranetzi...... 54 Lamna ditropis...... 34 Thresher shark...... 30 Bathyraja trachura ...... 62 “Leopard skate”...... 46 Whiteblotched skate...... 66 Bathyraja violacea...... 52 Longnose skate...... 42 Whitebrow skate...... 64

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