Japanese Journal of Ichthyology 魚 類 学 雑 誌 Vol.20,No.2.1973 20巻2号1973年

An Albino Zebra Shark Stegostoma fasciatum relatively common in teleostean fishes,especial- from the Indian Ocean,with Comments ly in the Pleuronectiformes.Its occurrence on Albinism in Elasmobranchs among elasmobranchs,however,has been rarely reported(Table 1). Kazuhiro Nakaya Specimens examined were preserved in 10% (Received November 15,1972) formalin after storage in freezing chambers and have been deposited in the Fisheries Museum of A white colored zebra shark identified as the Faculty of Fisheries,Hokkaido University, Stegostoma fasciatum(Hermann)was captured Japan.Sampling data,sex and size were listed on Jan.4,1964 in the Indian Ocean,11•‹23'S, in Table 2.All the measurements were taken 117•‹17'E by the T.S.Oshoro Maru of Hokkaido after the fixation in formalin.Measurements University.The shark's appearance fitted the were made according to Bigelow and Schroeder descriptions of the species(Tanaka,1911) (1948)and proportional dimensions were ex- except for its lack of body pigmentation.In pressed as percent of total length.Morpho- this paper,the albino zebra shark was com- metric comparisons were made between the pared with natural colored specimens of about albino and normal specimens of about same the same size. length in order to eliminate effect of sexual Albinism is known for many animals and is dimorphism and growth.

Table 1.Albinisms in elasmobranch fishes reported up to the present .

Table 2.Sampling data of specimens of the zebra shark,Stegostoma fasciatum.

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Observations Anal On:vertical height 4.5,4.9 Proportional dimensions are shown below in Caudal On:upper Lobe 42.6,42,2;lower lobe order of whiite and normal female.As the 5.3,5.2 origins of the dorsal and anal 6 were obscure, Inierspace between:2nd dorsal and caudal some measurements could not he made. 8.1,8.9;anal and caudal 3.2,3.6 Distance from origin to origin of:pectoral Trunk at origin of pectorals:width 1.7,11.1; height 14.1,13.1 and pclvics 20.4,20.8 Snout in front of:(whit 5.1,4.8;outer Morphological characters except body color, nostrils 0.9,1.1;mouth 3 6,3.1 of the albino specimen are within the range of ad:width 13.5,13.9,height He 11.9,12.5 intt tspecili,viidation of normal zebra sharks. White specimen:Body color uniformly Distance frt ii tip of snout to:spiracle 7.4, 7.3;1st gill opcniin:11.6.1.1.1;5th gill. white with very slight red tint;none of black spots or blotches present abo\e and below; opening 16.4,I.origin of pectorals margin of fins greyish.Iris blackish brown. 14.2,14.0;posteiposttip of 1st dorsal 41.0, 42.3;posterior tip of 2nd dorsal 53.7,53.6; Normal specimens:Ground body color origin or ippere.lal58.4,58.3;origin of dirty yellow;many blackish brown spots some- lower I 58.5,59.1 what larger or smaller than orbit present on dorsal and lateral parts of body,dorsal fins, Eye:horizohial diameter 1.0,1.0 Month:.4,5.6;height 0,0 caudal fin,and upper sides of pectoral and Labial furrow:upper 1.4,1.4;lower 1.2,1.4 pelvic fins.Blackish browi spots on bead Nostrils:distance between inner ends 5.1, smaller anteriorly,without spots near tip of 5.2 snout.Yeliowish white on ventral part of Gli opening lengths:1st 2.3,2.5;2nd 2.8, body and lower sides of pectoral and pelvic fins. 2.6;3rd 2,8,2.8;4th 2.4.2.4;5th 2.4,2.2 Iris blackish brown. Pecioral:firu outer margin 18.8,19.1;inner Discussion margin 5.4,5.0;disial margin 15.6,15.4 First dorsal fin:ve:tical height 5.6,5.4 In spite of the difficulties in obtaining body Sec;ht 2.8,28. rneasuremv:s,no morphometric differences

Fig.1.Albino and nort zebra shark,.Sirgostoma fasciatun.Top:Albino specimen,1850mm TL, fc:nale,collected from the Indian,Ocean F-751).Bottom:Normal specimen,1735mn'FL,male, collected from the South China Sea (F-2499).

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were found between the specimens examined. Point, San Francisco Bay. California Fish Game, Most proportional differences were within one 39(2): 237-243, figs. 1•`3. percent.The greatest difference was 1.4%in Herald, E. S., W. Schneebeli, N. Green, and K . trunk breadth,a factor which may have been Innes. 1960. Catch reports for seventeen shark an artifact of preservation. dervies held at Elkhorn Slough, Monterey Bay, On examining the albino specimen,it would California. California Fish Game, 46 (1): 59•`67 . Joseph, E. B. 1961. An albino cownose ray have been helpful to know the color of the eyes , Rhinoptera bonasus (Mitchill) from Chesapeake on capture.Though the color of the eyes of Bay. Copeia, 1961 (4): 482-483, fig. 1. the white specimen was not investigated when McKenzie, M. D. 1970. First record of albinism

captured,the specimen must have had normal in the hammerhead shark, Sphyrna lewini (Pisces; eyes,because the white specimen had blackish- Sphyrnidae). J. Elisha Mitchell Sci. Soc., 86(1):

brown iris similar to that of "normal" 35-37, fig. 1. preserved specimens in formalin.Hence I con- Schwartz, F. J. 1959. White cownose ray, Rhi- clude the Indian Ocean specimen was a noptera bonasus, from Tangier Sound, Maryland. Maryland Tidew. News, 15(3) : 12. partial albino, which is the largest albino elasmobranch fish reported. Tanaka, S. 1911. Figures and descriptions of the fishes of Japan. Daichi Shoin, Tokyo. 4: 51•`70 It is interesting that this albino zebra shark , has grown so large in spite of its white color pls. 16-20. Traquair, R. H. 1893. An unusually coloured ex- which appears to be disadvantageous to the ample of the thornback, (Raia clavata, Linn .). specimen in making it more conspicuous at the Ann. Scot. Nat. Hist., 1893: 25, pl. 1. bottom. Wilson, E. 1951. Colour deficiency in skate

(Raiidae). Proc. Zool. Soc.London, 121: 557-559, Acknowledgments pl. 1. I express thanks to Professor Shun Okada and Associate Professer Takao Igarashi of Hokkaido (Laboratory of Marine Zoology, Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido, 040 University for the critical reading of the , Japan) manuscript.I am also indebted to Dr.Frank J.Schwartz of the University of North Carolina イ ン ド洋 産 トラ フ ザ メ の 白 子 仲 谷 一 宏 for advices,suggestions,and critical reading of 1964年1月,イ ン ド洋 で 全 長1850mmの 白 い ト ラ

the English manuscript.I am grateful to Dr. フ ザ メ が 捕 獲 さ れ た 。 こ の 個 体 と 正 常 な ト ラ フ ザ メ を Kunio Amaoka of Hokkaido University for his 比 較 し た 結 果,こ の 白 い ト ラ フ ザ メ と正 常 な ト ラ フ ザ critical comments and advice in the course of メ の 間 の 唯 一 の 差 は 体 色 で,眼 の 色 を 含 め 他 の 形 質 に the study. は ま っ た く差 異 が 見 ら れ な か っ た 。 し た が っ て,本 個 体 を ト ラ フ ザ メ の 不 完 全 な 白 子(partial albino)と 断 Literature cited 定 し た. 現 在 ま で 板 鯉 魚 類 の 白 化 現 象 は 本 例 を 含 め10例 が Bigelow, H. B. and W. C. Schroeder. 1948. Sharks. 報 告 さ れ て い る が,本 例 の よ う に 大 き な 個 体 は 珍 ら し In Fishes of the Western North Atlantic. pt. 1. く興 味 深 い 。 Sears Found. Mar. Res., 59-576, figs. 6•`106 . Herald, E. S. 1953. The 1952 shark dervies at (040函 館 市 港 町3の1の1北 海 道 大 学 水 産 学 部 動 物 Elkhorn Slough, Monterey Bay and at Coyote 学 教 室)

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