SYNOPSIS of BIOLOGICAL DATA on SKIPJACK Katsuwonus Pelamis (Linnaeus) 1758 (INDIAN OCEAN)
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Species Synopsis No, 21 FAO Fisheries Biology Synopsis No, 64 FIb/S64 (Distribution restricted) SASTTuna SYNOPSIS OF BIOLOGICAL DATA ON SKIPJACK Katsuwonus pelamis (Linnaeus) 1758 (INDIAN OCEAN) Exposé synoptique sur la biologie du bonite à ventre rays Katsuwonus pelamis (Linnaeus) 1758 (Océan Indien) Sinopsis sobre la biología del bonito de vientre rayado Katsuwonus pelamis (Linnaeus) 1758 (Océano Indico) Prepared by S. JONES and E. G, SILAS Central Marine Fisheries Research Institute Mandapam Camp, India FISHERIES DIVISION, BIOLOGY BRANCH FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 1963 663 FIb/S64 Skipjack 1:1 1 IDENTITY Laccadive Sea (Minicoy Island) caught by pole and line during January 1960 and November 1961 1.1 Taxonomy are as follows: 1.L1 Definition Head 29, 6 to 30. 7;first predorsal distance 33,6 to 34.9; second predorsal distance 60.5 Phylum VER TEBRATA to 62.9; preanal distance 64. 2 to 67. 5; prepelvic Subphylum Craniata distance 32. 9 to 35. 6;greatest depth of body Superclass Gnatho stomata 23,0 to 26.3; length of pectoral l3.l.to 16.7; -Series Pisces distance between origin of pectoral and first Class Teleostomi dorsal 13.1 to 15.5; base of first dorsal 24.5 to Subclass Actinopterygii 28,4; base of second dorsal (excluding finlets) Order Perciformes 7,4 to 9.1; base of second dorsal including fin- Suborder Scombroidei lets 31,8 to 349; caudal spread 25,6 to 26,5; Family Scombridae longest (first) dorsal spine 13. 0 to 15. 6;length Subfamily Thunninae of second dorsal 6.0 to 9.3; length of anal4.6 Genus Katsuwonus Kishiiiouye, to 8. 4;length of pelvic 10, 3 to II. 9;least depth 1915 of caudal peduncle 1. 9 to 2. 2;greatest width of Katsuwonus pelamis caudal peduncle at keel 3. 5 to 4. 5;length of (Linneus), 1758 maxila 10. 2 to 11, 9; diameter of iris 4. 3 to 5. 9; longest gill-raker 3,9 to 4,4 and longest gill 1,1. 2 Description filament 6.7 to 7.4 percent in total length. (Fig. 1). - Genus Katsuwonus Kishinouye 1915 The disposition of the different organs of the viscera and the nature of the liver and gall bladder Body robust2 rounded in cross-section, ure shown in Fig. 2. teeth on jaws about 40 in each, absent on vomer and palatine; corselet well defined; For meristic characters see section 1.3.1. hardly any scales visible on rest of body;inter- space between first and second dorsa hardly Color in life is steel blue tinged with lustrous exceeding eye diameter; margin of first dorsal violet along dorsum and decreasing in intensity fin strongly concave; lateral line with a decided cn sides to level of pectoral base; half of body downward curve below second dorsal; gill- including abdomen whitish to pale yellow; evan- rakers number 50 to 63 of which 33 to 42 n ascent vertical light bars seen on sides of body lower limb; generally four dark conspicuous immediately after captar; fading within an hour; longitudinal bands along side of body below so also yellowish tinge on abdomen; conspicuous lateral line, none above lateral line.Internal sour to six longitudinal dusky to black stripes characters include long gall-bladder, nearly below lateral line on each side of body; light free from liver running along dorsal side of reyish tinge on underside of mandible (chin) liver,As in Thunnus and Sarda, a pair of ìnerging posteriorly with whitish color of lower cutaneous arteries branch just behind insertion Ia1f of body. of pharyngeal muscles, but passing through kidneys, arteries turn outward and forward in- In preservative (formalin) corselet area is stead of backwards; epaxial and hypaxial light grey tinged with yellow, upper half of body arterial branches running below and above first shining grey; between corselet scale along first rib respectively, well-developed; vertebrae dorsal base and along second dorsal base distinct 20 + 21 (41). black patches; so also dorsum of head; chin dark grey; lower half of body pale whitish to light Katsuw nus po amia (Linnaeus) 1758 grey, but generally four conspicuous longitudinal blick stripes present; spine of first dorsal fin Body proportions expressed as percentages dusky, but i.nter-spinous membrane whitish be- of total lengthLfrom tip of snout to fork, tween anterior spines, but margin tinged dusky latter slightly flexed, Marr and Schaefer (1949)7, ketween last few spines; second dorsal and dorsal for ten specimens 283 mm to 458 mm from finlets dusky with narrow white margins; so also 664 L Fig. iKatsuwonus pelan-uis (Linnaeus) FIb/S64 Skipjack 1:3 Fig, Z (a) Disposition of the visceral organs, and (b)of liver and gall-bladder in Katsuwonus pelamis (Linnaeus) LV - liver IN- intestine PC - pyloric caeca ST - stomach GB - call -blad'or 666 1:4 FIb/S64 Skipjack pectorals and pelvics; blackish patch along 1, 3 General variability abdomen for whole length of pelvic s;anal and finlets lighter; median caudal peduncular keels 1. 3.1 Subspecific fragmentation blackish with light margin dorsally, but light (races, varieties, hybrids) grey ventrally, - Meristic counts Hardly any color difference bètween small- est and largest adult specimens in the collection. Details of meristic counts for specimen from Indian Ocean is given in Tables II and Juvenile coloration for a specimen 27 mm in III. total length: "The pigmentation in the specimen is comparatively denser on the dorsal aspect of So far no attempts have been made to dis- the head and body,The spinous dorsal has tinguish populations, varieties or races, nor patches of chromatophores on the upper half of do the counts given above throw much light on the fin membranes between the anterior eight the subject,Generally XIV - XVI spines are rays,The ventral side of the body is practical- present in the first dorsal and this makes the ly devoid of chromatophores except for a few on minimum count of XII given by Smith (1961) each side along the base of the anal fin and fin- exceptionally low. letsYt. (Jones 1959 a). Natural hybridization is unknown, 1. 2 Nomenclature Albinisrn or melanism have not been reported. 1. 2,1 Valid scientific name However, at Minicoy Island in the Laccadive Katsuwonus pelamis (Linnaeus) 1758 Sea, among freshly caught skipjack, in a lot of a hundred or so specimens, two or three may 1.2.2 Synonyms be a much lighter color, the lateral bands (specially for Indian Ocean area) appearing faded and the dorsum being light dusky, but retaining the basic color pattern, (Only taxonomic references are cited here Such occurrences in small numbers are not chronologically). infrequent and these specimens can be easily detected in fresh landings. Scomber pelamis Linnaeus 1758 Scomber pelamides Lacépède 1803 Thynnus vagans Lesson 1828 Euthynnus pelamis Deraniyagala 1933; Molteno 1948; Fourmanoir 1957; Smith 1961 Euthynnus (Katsuwonus) pelamis Fraser- Brunner 1950; Deraniyagala 1952; Mendis 1954 Euthynnus (Katsuwonus) pelamys Fourmanoir 1960 Gymnosarda pelamys Barnard 1925 Thynnus pelamys Cuvier and Valenciennes 1831; Gmnther 1860; Day 1888, 1889; Gilchrist 1902 Katsuwonus pelamis Kishinouye 1915; Serventy 1941; Rosa 1950; Munro 1955, 1958; Jones and Silas 1960, 1962; Ta]bot 1962; Whitley 1962 1. 2, 3 Standard common names, vernacu- lar names (See Table I). 667 FIb/S64 Skipjack 1:5 Table I Common and vernacular names ounf ry Standard Vernacular Name(s) Common name Aden, Gulf of Af Muss; Dabub (Somali dialect); Hargheiba (Alula dialect) Australia Striped tuna Watermelon; Skipjack Ceylon Skipjack Baleya; Alaguduva (Sinhalese dialect); Ocean Bonito; striped tuna East Africa and Skipjack Sehewa (Kiswahili dialect; also Zanzibar refers to Euthynnus sp., Auxis spp.) India Oceanic skipjack Bonito; Kali-phila--mas (Mahal dialect, Laccadives); Vari Choora (Malayalam, Kerala coast) Choora and Metti (Malayalam, Arniiii Island, Laccadives) Indone sia Bonito Tjakalang;Tjakalang-lelaki; -Tjakalang -perempuan; Tjakalang- roe rah Madagascar Bonite Bonite a venre raye; Diodary (Sakalawa dialect)Mbassi (Swahili dialect) Maldive Islands Kali-phila-mas Runion, Mauritius Bonite South Mr.ica Skipjack Oceanic Bonito; Lesser tunny; Bonito; Watermelon; Katunkel 668 1:6 FIb/S64 Skipjack Table II Meristic characters for ten specimens of Katsuwonus pelamis (Linnaeus) from Minicoy Island, Laccadive Sea Dorsal spine Dorsal finlets Anal finlets Pectoral No. 15 16 8 8+l(=9)9 7 7+1(8) 26 27 28 F. 2 8 6 2 1 7 3 3 6 1 N =10 N =9 N=lO N=l0 Mean= l5 8 Mean = 8.4 Mean 7,3 Mean = 26,8 Gill- rakers Upper limb Lower limb 14 15 16 17 18 19 20 32 33 34 35 36 37 38 39 40 1 3 2 2 2 - - - - 2 - 24 1 1 - N=lO N=lO Mean 16.1 Mean = 36.5 Total gill-rakers 48 49 50 51 52 53 54 55 56 57 58 - 2 1 2 2 1 2 - - - N = 10 Mean = 52, 5 No. = Counts; F = Frequency of occurrence; N = Number of specimens 669 Meristic characters as given byTable various 111 authors for Katsuwonus pelamis Charac- Africa (Linnaeus)gasMada- car fromtrallaAus- the IndonesiaIndian Ocean Ceylon Laccadivs(India) Dlters XIV-xvWilliams(1962) XII-XVISmith(1961) XIV-XVTalbot(1962) Fourma-(1957)noirXV XIV-XVIMunro(1958) Beaufort(1951)Xvde XV-XVIIDeyagala(1952) rani - Munro(1955)XV JonesXV-XVI(1962)Silas XII-XVIrangeTotal finletsPectoralD2 + 13-15+7-8 12-13+8 14 8-15+ 14-168 + 14-1626-297-9 + i(=14-16) ii,12-14+8 24 27-30(=15)3312+8 ii,(=14-16)ii,+8 12-1424 13-1426-288-9 + 12-16+26-297-9 f mie t s 14-15+7 I-III(=13-15) 12 15+7 14-167 + 14-15+7-8 1Ì1(=15)(= 26)12 + 12-133-4 + (=15)íli(= 26)12 + 13-14+7-8 13-17-8 6+ rakersGill- (=53-56)153 8-40-16 + ++35 7-8 36-318-20+(=56) 8 33-4217-21+ 7 40-i-35-7 7 (50-55)34-3914-48+ 33-414- 21+ 2 t.