Spotted Ratfish Hydrolagus Colliei

18 Spotted Ratfish Hydrolagus colliei EGG CASE Diagnosis The only chondrichthyan Range Gulf of Alaska to Baja California in Alaska with a single gill opening on and Gulf of California. each side of the head. Opercle without skeletal support; anterior dorsal fin Depth Intertidal to 971 m. with a long, sharp spine. Remarks The spotted ratfish is Dentition Teeth fused to form quite common throughout the grinding plates. Alexander Archipelago and is regularly encountered on NMFS bottom trawl Coloration Silver to golden brown or surveys as far north as Lituya Bay. In Alaska waters, the spotted ratfish is found in green dorsally with many prominent The three isolated records from the the Gulf of Alaska. white spots; white ventrally; eyes northern and western Gulf of Alaska reflect green. are unverified RACE database records from the mid-1980s. Body shape Caudal region tapering to a point. Similar species The spotted ratfish is the only species of chimaera known Reproduction Oviparous; accessory from Alaska. One or perhaps two clasping organ on head in males. Egg additional undescribed species are case maximum size is 20 cm long. known from deep water off California. Maximum length 100 cm. Spotted Ratfish Hydrolagus colliei 19 20 Spiny Dogfish Squalus acanthias Upper tooth Lower tooth Diagnosis The only Alaska species of Depth Generally benthic, intertidal to shark with a spine on the leading edge 1,244 m. of each dorsal fin; anal fin absent. Remarks Although the spiny dogfish Dentition Upper and lower teeth with has been reported from throughout single low cusp. the Bering Sea and as far north as Kotzebue Sound (Mecklenburg et al. Coloration Gray to medium brown 2002), trawl survey records from the dorsally, with small white spots; pale past 15 years indicate that they are very gray to white ventrally. rare in this region. Body shape Elongate, slim, with In Alaska waters, the spiny dogfish is found Similar species The spiny dogfish is in the Gulf of Alaska and Bering Sea, with one distinctly heterocercal caudal fin. the only shark in Alaska with a spine on record from Kotzebue Sound. the leading edge of each dorsal fin. The Reproduction Viviparous (yolk-sac). only other shark in Alaska that lacks an Maximum length 2 m. anal fin is the Pacific sleeper shark (see p. 22). Range Worldwide in temperate and subarctic waters. Spiny Dogfish Squalus acanthias 21 22 Pacific Sleeper Shark Somniosus pacificus Upper tooth Lower tooth Diagnosis The only Alaska species of Depth Benthic, intertidal to 2,000 m. shark with the combination of no anal fin and no dorsal spines. Remarks The Pacific sleeper shark (sometimes called the mud shark) is Dentition Upper teeth long, narrow, encountered throughout the Gulf of and sharp; lower teeth with short low Alaska and Aleutian Islands, as well cusps. as on the outer shelf and upper slope of the Bering Sea. The Chukchi Sea Coloration Gray to black dorsally; only specimen, reported by Benz et al. slightly lighter ventrally. (2004), washed up onshore near Point In Alaska waters, the Pacific sleeper shark is Hope. found in the Bering Sea, Aleutian Islands, and Body shape Large, stout, and flabby, Gulf of Alaska. with small flaplike, flexible fins. Similar species The Pacific sleeper shark is one of only two sharks in Reproduction Viviparous (yolk-sac). Alaska that have no anal fin. The other Maximum length Documented to is the spiny dogfish, which has a strong 4.4 m, possibly to 7 m or more. spine at the leading edge of each dorsal fin. The small, flexible, flaplike Range North Pacific from Chukchi Sea fins and posterior position of the first to Baja California in the eastern Pacific; dorsal fin are also characteristic of this to Taiwan in the western Pacific. species. Pacific Sleeper Shark Somniosus pacificus 23 24 Bluntnose Sixgill Shark Hexanchus griseus Upper tooth Lower tooth Diagnosis The only Alaska species of Depth Benthic or pelagic, surface to shark with six gill slits on each side of 2,500 m. the head; also the only species with a single dorsal fin. Remarks The bluntnose sixgill shark has only been recorded twice in Alaska Dentition Lower jaw with 6 comb- waters, once south of Unimak Pass shaped teeth. (Larkins 1964) and more recently from Southeast Alaska on a 1999 NMFS Coloration Dark gray to brown bottom trawl survey. dorsally; light gray to white ventrally. The bluntnose sixgill shark has been recorded Similar species The bluntnose sixgill twice in Alaska. Body shape Stout, with broad, shark is the only shark in Alaska with rounded head. six gill slits on each side of the head. The only other sharks in the world Reproduction Viviparous (yolk-sac). with six gill slits are the bigeye sixgill Maximum length 4.8 m. shark (Hexanchus nakamurai), frill shark (Chlamydoselachus anguineus), and Range Tropical and temperate North sixgill sawshark (Pliotrema warreni), all and South Pacific, North and South of which are only found in California Atlantic, and Indian Ocean; eastern waters and farther south. Aleutian Islands. Bluntnose Sixgill Shark Hexanchus griseus 25 26 Basking Shark Cetorhinus maximus Upper tooth Lower tooth Diagnosis The only Alaska species of Range Worldwide in temperate seas; shark with gill slits that nearly encircle northern Gulf of Alaska. the head. Also the largest species found in Alaska waters. Depth Pelagic, near surface. Dentition Teeth minute, hooked. Remarks According to Compagno (1984), the range of the basking shark Coloration Brown to gray or black extends to the Kenai Peninsula. The dorsally, often with irregular light indicated record in the western Gulf patches; lighter ventrally, often with of Alaska is from a 1981 NMFS bottom In Alaska waters, the basking shark is found in white blotches and spots. trawl survey. the Gulf of Alaska. Body shape Large and robust, with Similar species The basking shark is elongate snout. the second largest fish in the world (the whale shark is the largest). Its extremely Reproduction Viviparous large gill slits and minute hooked teeth (oophagous). distinguish it from all other sharks. Maximum length 10 m or more. Basking Shark Cetorhinus maximus 27 28 Brown Cat Shark Apristurus brunneus Upper tooth EGG CASE Lower tooth Diagnosis The only Alaska species Range Southeast Alaska to Central or of shark with two dorsal fins and the South America. leading edge of the first dorsal fin posterior to the leading edge of the Depth Benthic, 33-1,306 m. pelvic fin. Remarks The brown cat shark is Dentition Teeth with 3-5 cusps, the known from only two Alaska records, central cusp largest. both from Southeast Alaska. The northern record was reported by Coloration Uniform dark brown; fin Wilson and Hughes (1978), and the In Alaska waters, the brown cat shark is known margins darker brown to black. southern record was collected on a from only two records in the Gulf of Alaska. 2005 NMFS bottom trawl survey. Body shape Elongate, small; caudal fin long, almost entirely below body Similar Species The brown cat shark midline. is the smallest shark in Alaska. The longnose cat shark (Apristurus kampae) Reproduction Oviparous. Egg case does not occur north of southern 50 mm. Oregon, and can be distinguished from the brown cat shark by its larger gill Maximum size 71 cm. slits, and white fin edges. Brown Cat Shark Apristurus brunneus 29.

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